GPS for IFR Operations Version 3. 01 November 5, 2002 Thomas B. Bahder, Ph. D. , CFII Copyright C 2002 by Thomas B. Bahder All Rights Reserved. No part of this document can be modified. Permission is hereby granted to disseminate this document in its entirety, free of charge, for educational purposes only. No fees can be charged for this document, except nominal reproduction fees. For profit, no part of this document may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the author. 1
Notice of Disclaimer The author has made every attempt to present correct and accurate information in this tutorial. However, the author assumes no liability for any events that result from the use or misuse of the information presented here. Ultimately, it is every pilots responsibility to use the information provided by official FAA publications, such as the FAA Approved Flight Manual, Flight Manual Supplement, the AFD (Airport Facilities Directory), NOTAM’s, Aeronautical Charts, Advisory Circulars, the Aeronautical Information Manual and the Manual provided by the manufacturer of the GPS receiver. Software Version Used This tutorial is based on two GPS receivers: The II Morrow, Inc. GX 60 receiver and GX series simulator, version 3. 0, with the following option selected, GX 60, IFR, and APPR, and The Garmin GNS 430 receiver and Garmin 400 Series Windows Trainer simulator with software version 3. 00. At the time of this writing, GPS WAAS and LAAS were not yet authorized for IFR flight. 2
Introduction This tutorial presents the basic information that pilots need to use GPS to fly IFR (Instrument Flight Rules) in the U. S. National Airspace System. The tutorial assumes a basic understanding of navigation and instrument approach procedures using the traditional ground-based navaids, such as VOR, NDB, and ILS. Two receivers are used as examples of GPS receivers: the II Morrow Apollo GX 60 receiver and the Garmin GNS 430 receiver. However, this tutorial does not go into the level of detail required to operate each specific model of GPS receiver, or any other specific model of GPS receiver. This information must be obtained from the receiver manufacturer’s manual for that particular receiver as well as the FAA Approved Flight Manual and/or Flight Manual Supplement for the particular aircraft. 3
CONTENTS page Part I -- GPS System Overview …………………………. . 5 Part II -- Flying IFR ………………………………. . 30 Part III -- GPS Instrument Approaches …………………………. . … 40 Part IV -- Flying Nonprecision GPS Approaches ………………………. … 69 IFR GPS Simulator and Aircraft Checkout: GX 60 ……………………. …… 92 Part V -- Flying Approaches with Garmin 430 ………………. . ………………… 93 IFR GPS Simulator and Aircraft Checkout: GNS 430……………………. 100 World Wide Web Sites……………………………………. …… 101 References ………………. . ……………………. 102 4
Part I -- GPS System Overview 5
Evolution of Satellite Navigation Ù The science and technology of navigation has occupied man for generations. Initially, man navigated on the flat surface of the Earth using existing landmarks. Next, man learned that the surface of the Earth is really the surface of a sphere, and that the Earth orbits our sun. This refinement in our understanding gave rise to celestial navigation, which is based on carrying a good clock and making angular observations of the natural stars. A drawback of celestial navigation is that the sky must be clear enough to see the stars. With the development of radios, a new class of navigation aids was borne. At first, these aids consisted of Earth-based radio beacons, such as VORs, LORAN, and Omega. Finally, man created Earth satellites that send out radio beacons that are not obscured by clouds. These artificial satellites allow highly precise and reliable navigation in the vicinity of the Earth. Ù Historically, there were several satellite systems that were primarily designed for navigation: Ù Ù Transit -- ~1960’s operational system, U. S. Navy/Johns Hopkins Applied Physics Laboratory (APL) Timation -- ~1960’s experimental system, U. S. Naval Research Laboratory, U. S. Navy/APL 621 B -- 1960’s study program , U. S. Air Force, Aerospace Corp. GPS (Global Positioning System -- NAVSTAR) -- US Air Force n 1973 GPS program was established by JPO (Joint Program Office) 1978 Air Force Began Launches of Block I (experimental) satellites 1989 First Launch of Block II (operational) satellites 1995 GPS FOC (Full Operational Capability) announced n GLONASS (Global Navigation Satellite System) Russian version of GPS, developed n n n essentially in parallel with GPS 6
The GPS System Segments Space Segment User Segment GPS Receiver Master Control Station Ground Tracking Stations Control Segment 7
The GPS Satellite Constellation (Space Segment) Graphic used by permission from Peter H. Dana, The Geographer's Craft Project, Department of Geography, The University of Texas at Austin. n n n n 24 Satellites in nearly circular orbits around Earth 6 orbital planes 4 satellites in each orbital plane 20, 200 km altitudes (about 4 Earth radii) Orbital periods are 11 hours 58 minutes Each satellite carries 4 atomic clocks, one operational and three spares Constellation is designed so that at least 4 or 5 satellites are in view from anywhere on Earth 8
GPS Control Segment Stations track GPS satellite signals and relay them to the Master Control Station in Colorado Springs Master Control Station Determines GPS satellite positions (ephemeris) and uploads this information into each satellite Satellites broadcast their positions to GPS users 9
GPS Block IIR Satellite -- Artist Conception 10
GPS Block II Satellite 11
Launch of GPS Satellite Maiden Launch of Delta II Booster with SVN 14 as Payload SVN 14 inside Delta II Booster 12
GPS Receiver (User Segment) n n n GPS receiver identifies a given satellite by matching the (unique) code from that satellite Data superimposed on the code gives satellite position (ephemeris) and GPS system time at which the signal was emitted Receiver has a clock and it calculates how much time it took the signal to travel from the satellite to receiver The speed of light is 186, 000 miles/second, and the distance from satellite to receiver is computed Corrections are made due to slowing down of signal through atmosphere Using the computed distances to 4 satellites, the receiver computes its 3 -dimensional position by mathematical triangulation 13
GPS Altitude Displayed by Receiver: CAUTION Mean Sea Level is NOT the same as the WGS-84 ellipsoid n n n WGS-84 (World Geodetic System 1984) is the system of coordinates used by GPS In the WGS-84 system of coordinates, an ellipsoid is defined to approximate the average mean sea level. Computed GPS altitude is the height above the WGS-84 ellipsoid, not True MSL altitude. CAUTION: The altitude above the WGS-84 ellipsoid can be different from the MSL altitude on the aircraft altimeter by hundreds of feet. This is a serious consideration during instrument approaches. Use your altimeter! Typically, GPS vertical position is less accurate than GPS horizontal position. 14
II Morrow GX 60 GPS Receiver TSO-C 129 A 1 certified for Enroute, Terminal and Nonprecision Approach Operations 15
The GPS System Segments (continued) n The GPS consists of three segments: SPACE, CONTROL and USER Ù The SPACE segment n Consists of 24 operational satellites in six orbital planes, (four satellites in each plane). The satellites operate in approximately circular 20, 200 km (10, 900 nm) orbits at an inclination angle of 55 degrees and with a 12 -hour period. From a given point on Earth, each satellite appears at the same place every 23 hours 56 minutes. Ù The CONTROL segment n Consists of five Monitor Stations (Hawaii, Kwajalein, Ascension Island, Diego Garcia, Colorado Springs), three Ground Antennas, (Ascension Island, Diego Garcia, Kwajalein), and a Master Control Station (MCS) located at Falcon AFB in Colorado. The monitor stations passively track all satellites in view, accumulating ranging data. This information is processed at the MCS to determine satellite orbits and to update each satellite's navigation message. Updated information is transmitted to each satellite via the Ground Antennas. Ù The USER segment n n Consists of GPS users on the ground and in the air with receivers capable of locking on to the satellite signals. Some receivers have RAIM (see next page) 16
RAIM -- Receiver Autonomous Integrity Monitoring n n n n GPS receivers for critical applications, such as IFR flight, have RAIM algorithms that check integrity of GPS data Integrity -- The ability of a system to provide timely warnings to users when the system should not be used for navigation To perform the RAIM function, at least one extra satellite, in addition to the ones used for navigation, must be tracked by the receiver RAIM algorithms need a minimum of 5 satellites, 4 for position determination plus one extra Alternative RAIM scheme: 4 satellites plus baro-aiding provided by barometer -- the altimeter setting must be entered manually Some receivers are capable of isolating which satellite signal is corrupt and can remove it from the position solution. These receivers need 6 satellites, or 5 satellites plus baro-aiding. Without RAIM capability, the pilot has no assurance of accuracy of GPS position 17
Causes of RAIM Outages n n n Insufficient number of satellites Poor satellite geometry leads to large position errors Change in aircraft dynamics, such as banking, obscures the GPS satellite signal (which must be received line-of-sight) 18
GPS Positioning Services At least 4 satellites must be simultaneously tracked to compute position in 3 -dimensions n SPS (Standard Positioning Service) n PPS (Precise Positioning Service) Only available to U. S. Department of Defense and other Authorized Users Available to all users, such as civilians, FAA, and other civilian organizations n Positioning Accuracy: Ù 100 meters horizontal position, 95 % of the time Ù 300 meters horizontal position, 99. 99 % of the time n Positioning Accuracy: Ù ~16 meters horizontal position, 98 % of the time n C/A code (Course Acquisition Code) Broadcast on Single Frequency L 1: 1575. 42 MHz n P-code, (Precise Code, or Y-code (encrypted)) Broadcast on Two Frequencies L 1: 1575. 42 MHz L 2: 1227. 6 MHz Accuracy of signal is intentionally degraded by U. S. Do. D to the 100 meter level, called SA (selective availability) n n The two frequencies, L 1 and L 2, allow better compensation for atmospheric effects (allows measurement of ionospheric delay) 19
Determining User Position A n n n B 1. Consider two satellite clocks, labeled A and B, that are located at known positions and are synchronized. 2. Assume that you (the user) are located somewhere between clocks A and B, and that you have a clock that is synchronized with clocks A and B 3. Assume that you simultaneously receive radio signals from clocks A and B, and these signals tell you the time at which the signals left clocks A and B, respectively. 4. Using the known time of arrival of the signals at your position, and the time the signals left each clock, you can figure out the distance that each signal traveled (shown by the arrows), since each signal travels at the speed of light, 186, 000 miles/second. You can then draw a sphere centered at each clock with a radius equal to the distance traveled from that clock. 5. The intersection of the two spheres is a circle. Your position is somewhere on this circle. 6. We need a third satellite, to resolve the ambiguity in position along the circle. 20
Determining User Position (continued) P 2 B A P 1 C n n 7. Adding the simultaneous reception of signals from a third satellite C, adds another sphere centered at C. 8. The intersection of the circle (shown in dark) with the sphere centered at C gives our probable position as two points, shown as P 1 and P 2. 9. Finally, the simultaneous reception of a fourth satellite (not shown) gives another sphere, which resolves the ambiguity in position between points P 1 and P 2. 10. When radio waves pass through the atmosphere, the waves are delayed. These delays are taken into account to produce an accurate user position. 21
GPS Signal Details n n n n The coarse/acquisition (C/A) code has a 1. 023 MHz chip rate, a period of one millisecond (ms) and is used by civilians for navigation. This code is also used by Do. D, primarily to acquire the P-code. The precision P-code has a 10. 23 MHz rate, a period of seven days and is the principal navigation ranging code for Do. D. The Y-code (encrypted form of the P-code) is used in place of the P-code whenever the anti-spoofing (A-S) mode of operation is activated. The C/A code is available on the L 1 frequency and the P-code is available on both L 1 and L 2. The different satellites all transmit on the same frequencies, L 1 and. L 2, but each satellite has a unique code. A GPS receiver locks onto and tracks a given satellite by correlating an internally replicated code (inside the receiver) for that given satellite, with that coming from space. If the correlation is successful, the receiver is able to track the satellite. Due to the spread spectrum characteristic of the signals, the system provides a large margin of resistance to interference. Each satellite transmits a navigation message containing its orbital elements, clock behavior, system time and status messages. In addition, an almanac is also provided which gives the approximate data for each active satellite. This allows the user set to find all satellites once the first has been acquired. 22
Differential GPS This basic idea of differential GPS is used in WAAS and LAAS, and all other augmentation schemes. The aircraft receives the GPS signals as well as the broadcast corrections from the GPS receiver station, improving availability and integrity of the stand-alone GPS system position. 23
FAA GPS Augmentations n WAAS (Wide Area Augmentation System) n LAAS (Local Area Augmentation System) n Will provide enroute navigation plus Category I-type approaches for most airports n Will provide navigation capability in areas where WAAS is not available plus Category II/III approaches and landings at selected locations n LAAS Capable Receiver Needed n Similar to WAAS, LAAS will broadcast its correction to the standard GPS signals, but will use a VHF radio datalink from a ground-based transmitter located at each airport. n It is expected that the end-state configuration will pinpoint the aircraft's position to within one meter or less. n Beyond Category III, the LAAS will provide the user with a navigation signal that can be used as an all weather (airport) surface navigation capability for taxing. n The LAAS is intended to complement the WAAS and function together to supply users of the U. S. NAS with seamless satellite based navigation at locations where the WAAS is unable to meet existing navigation and landing requirements (such as availability). In addition, the LAAS will meet the more stringent Category II/III requirements that exist at selected airports. n n WAAS Capable Receiver Needed WAAS is a GPS-based navigation and landing system that will provide precision guidance to aircraft at thousands of airports and airstrips where there is currently no precision landing capability. Systems such as WAAS are known as satellite-based augmentation systems (SBAS). WAAS is designed to improve the accuracy and ensure the integrity of information coming from GPS satellites. The FAA is moving directly to a Lateral Navigation/Vertical Navigation (LNAV/VNAV) capability using WAAS with expected capability in 2003. Concurrently, the FAA will evaluate the approach to achieve Global Navigation Satellite System (GNSS) Landing System (GLS) capability in later years. 24
WAAS –How it Works EXCERPT TAKEN FROM WEB SITE: http: //gps. faa. gov/Programs/index. htm Unlike traditional ground-based navigation aids, WAAS will cover a more extensive service area. Wide area ground reference stations (WRS) have been linked to form a U. S. WAAS network. Precisely surveyed ground reference stations receive signals from GPS satellites and any errors in the signals are identified. Each station in the network relays the data to one of two wide area master stations (WMS) where correctional information for specific geographical areas is computed. A correction message is prepared and uplinked to a geostationary communications satellite (GEO) via a ground uplink station (GUS). This message is broadcast on the same frequency as GPS (L 1, 1575. 42 MHz) to future GPS/WAAS receivers on board aircraft flying within the broadcast coverage area of WAAS. The WAAS will improve basic GPS accuracy, to approximately 7 meters vertically and horizontally; system availability, through the use of geostationary communication satellites (GEOs) carrying navigation payloads; and to provide important integrity information about the entire GPS constellation. 25
LAAS – How it Works EXCERPT TAKEN FROM WEB SITE: http: //gps. faa. gov/Programs/index. htm Local Area Augmentation System (LAAS) ground facility (LGF) includes 4 Reference Receivers (RR), RR antenna pairs, redundunt Very High Frequency Data Broadcast (VDB) equpment feeding a single VDB antenna, and equipment racks. These sets of equipment are installed on the airport property where LAAS is intended to provide service. The LGF receives, decodes, and monitors GPS satellites information and produces correction messages. To compute corrections, the ground facility calculates position based on GPS, and then compares this position to their known location. Once the corrections are computed, a check is performed on the generated correction messages to help ensure that the messages will not produce misleading information for the users. This correction message, along with suitable integrity parameters and approach path information, is then sent to the airborne LAAS user(s) using the VDB from the ground-based transmitter. Airborne LAAS users receive this data broadcast from the LGF and use the information to assess the accuracy and integrity of the messages, and then compute accurate Position, Velocity, and Time (PVT) information using the same data. This PVT is utilized for the area navigation (RNAV) guidance and for generating ILS-look-alike guidance to aid the aircraft on an approach. 26
International Initiatives Europe’s Galileo (EXCERPT TAKEN FROM http: //www. esa. int/export/esa. SA/GGGMX 650 NDC_navigation_2. html ) Galileo will be Europe’s own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civilian control. It will be inter-operable with GPS and GLONASS, the two other global satellite navigation systems. A user will be able to take a position with the same receiver from any of the satellites in any combination. By offering dual frequencies as standard, however, Galileo will deliver real-time positioning accuracy down to the metre range, which is unprecedented for a publicly available system. It will guarantee availability of the service under all but the most extreme circumstances and will inform users within seconds of a failure of any satellite. This will make it suitable for applications where safety is crucial, such as running trains, guiding cars and landing aircraft. The first experimental satellite, part of the so-called Galileo System Test Bed (GSTB) will be launched in late 2004. n n n Canadian WAAS Japanese MTSAT = MULTI-FUNCTIONAL TRANSPORT SATELLITE, for DGPS for Pacific region (see http: //www. mlit. go. jp/koku/ats/e/mtsat/role/01. html) European Geostationary Navigation Overlay System (EGNOS), (Excerpt taken from: see http: //www. esa. int/export/esa. SA/GGG 8 YN 4 UGEC_index_0. html) EGNOS receives signals from the GPS and GLONASS satellites and, using specialised hardware, adds a correction factor which makes them accurate to five metres or better. The signals are then beamed back into space, and broadcast by three civilian geostationary satellites. EGNOS-receiving equipment, fitted into vehicles, picks up this precise tracking information. 27
Some History -- GPS Date Rollover Issues n The GPS Joint Program Office has determined that all generations of GPS satellites are unaffected by the Year 2000 (Y 2 K) and GPS End of Week (EOW) Rollover Issues. However, the Civil GPS users may need to verify that their receivers and applications will work properly through these events. n Y 2 K Issue: Ù The Year 2000 rollover issue, commonly referred to as the Y 2 K problem, stems from the fact that many computer programs are using a two digit date field and assume the year is 19 xx. When the year 2000 arrives, a two digit date becomes '00' and could be interpreted as an invalid date. n End Of Week (EOW) Rollover Issue: Ù The EOW rollover problem is really a problem that occurs every 20 years. GPS system time, which counts weeks, started counting on midnight 5/6 January 1980, in modulo 1024 (0 -1023). On midnight 21/22 August 1999, the GPS week will rollover from week 1023 to week 0000. This could be interpreted as an invalid date. 28
GPS as Sole Means of Navigation Recent study requested by FAA and carried out by Johns Hopkins Applied Physics Laboratory concluded that GPS is adequate for “Sole Means of Navigation” Concerns: Integrity, satellite availability (failure scenarios), and jamming (intentional and non-intentional) ===> Implication for future of navigation---The future is GPS! 29
Part II -- Flying IFR 30
General Requirements for GPS Operations under IFR n n n n GPS navigation equipment must be approved in accordance with TSO C-129 Hand-held GPS are NOT approved for IFR GPS operation must be conducted in accordance with FAA approved Flight Manual or Flight Manual Supplement Aircraft using GPS must be equipped with approved, operational alternate means of navigation appropriate to the flight Active monitoring of alternate nav equipment is not required if GPS receiver uses RAIM Active monitoring of alternate nav equipment is required when RAIM capability is lost Aircraft navigating by IFR approved GPS are considered RNAV aircraft, i. e. , use /G suffix in ATC flight plan (AIM Table 5 -1 -2) Prior to a GPS IFR flight, pilot must review GPS NOTAM’s (DUATS has GPS NOTAM’s) 31
GPS NOTAM’s GPS satellite outages are issued as GPS NOTAM’s (Notices to Airmen) for known or scheduled outages n The effect of satellite outage on intended flight operation cannot be determined unless the receiver has a RAIM algorithm that allows excluding a given satellite that is predicted to be out of service, e. g. , II Morrow GX 60 has this capability. n DUATS, FAA briefers, and Automated Flight Service Stations will provide GPS RAIM availability during briefings. Get RAIM prediction if flying a GPS departure procedure. n Satellites are referenced by their PRN (Pseudo-Random Noise) code number. n EXAMPLE: To obtain GPS NOTAMs from GTE DUATS: http: //duats. com Choose “Abbreviated WX Briefing”, and fill in all required questions, select location as GPS, uncheck all items, but check the box for “Notices to Airmen (NOTAMs)” You will see GPS NOTAM’s such as: n **** NOTAMs **** !GPS 05/026 GPS PRN 4 OTS WEF 9905250600 -9905251800 !GPS 05/027 GPS PRN 27 OTS WEF 9905270430 -9905271100 32
General Requirements for GPS Operations under IFR (continued) n n n n GPS for oceanic operations can be used as soon as avionics are installed, provided general requirements are met (see AIM Table 1 -1 -7 on GPS IFR Equipment Classes/Categories). GPS domestic en route and terminal IFR operations can be conducted as soon as avionics are installed and general requirements are met II Morrow GX 60 receiver is GPS IFR Equipment Category/Class TSO-C 129 A 1 (oceanic, en route, terminal, and nonprecision approach capable) GPS Approach Overlay Program authorizes pilots to use GPS avionics under IFR for flying existing nonprecision instrument approaches, except localizer (LOC), localizer directional aid (LDA), and simplified directional facility (SDF) procedures. Authorization to fly GPS approaches is limited to U. S. airspace. FAA administrator must authorize GPS use in other airspace GPS instrument approaches outside U. S. airspace must be authorized by the appropriate sovereign authority 33
Alternate Airport Requirements n n n If your destination has no instrument approach, then you must file an alternate airport. If the weather at your destination requires that you file an alternate destination, then that alternate airport must have an instrument approach that is NOT a GPS approach. However, when arriving at the alternate destination, you may elect to use any approach procedure, including a GPS instrument approach. 34
Two Categories of GPS Approaches There are two categories GPS approaches for general purpose civilian use: n GPS Overlay Approaches -- associated with GPS Approach Overlay Program n Stand Alone Approaches -- Designed from the start with GPS in mind 35
GPS Approach Overlay Program n n n n Purpose of the Approach Overlay Program is to Transition from ground-based to satellite-based navigation facilities for approaches Overlay Program allows pilots to fly existing VOR, VOR/DME, NDB/DME, TACAN, and RNAV nonprecision instrument approach procedures Overlay Program is limited to U. S. Airspace GPS equipment may be used to fly all nonprecision approaches, except LOC, LDA, and SDF procedures. Approach Procedure Must be retrieved from the receiver’s database. If not in the database, the procedure cannot be flown. Required alternate airport must have an approach procedure other than GPS (or LORAN-C). Approach Overlay Program has three Phases 36
Phases of Approach Overlay Program n n Phase I (Ended in February 1994, when FAA declared GPS operational for civil operations) Phase II (“GPS” is not included in procedure name) Ù Began on February 17, 1994 Ù Certified GPS equipment can be used as the primary IFR flight guidance to fly an overlay to an existing nonprecision aproach, such as VOR, VOR/DME, NDB/DME, TACAN, and RNAV Ù Underlying ground-based navaid(s) for the approach must be operational Ù Avionics in aircraft for the ground-based navaid(s) must be installed and operational Ù Monitoring of the ground-based navaid(s) for the underlying approach is not necessary Ù During the approach, the avionics for the ground-based navaid(s) need not be operating if RAIM is providing integrity. Ù Approach should be requested by existing published approach procedure name, such as VOR RWY 24. n Phase III ( procedure name includes “or GPS” ) Ù Began April 24, 1994 when first IAP were published to include “or GPS” in name Ù Neither the traditional aircraft avionics nor the underlying navaid(s) need be installed, operational or monitored to fly the approaches Ù For GPS systems that do not use RAIM, the traditional avionics and ground-based navaid(s) that provide the equivalent integrity must installed and operational during the approach Ù For any required alternate airport, the traditional avionics and ground-based naviaid(s) that define the instrument approach and route to the alternate must be installed and operational Ù Approach should be requested by GPS procedure name, such as GPS RWY 24. 37
GPS NOTAM Use of GPS as Substitute for NDB and DME n Operators in the U. S. NAS are authorized to use GPS equipment certified for IFR operations in place of ADF and DME equipment for the following operations: Ù Ù Ù n Approved IFR GPS instrument approach operations include: Ù Ù n Determining the aircraft position over a DME fix. Flying a DME arc. Navigating to/from an NDB. Determining the aircraft position over a fix made up of a crossing NDB bearing. Holding over an NDB. Locating DME fixes and Locator Outer Markers (LOMs) Flying DME arcs Determining NDB cross-bearing fixes Navigating to/from and holding over NDBs See complete text of this NOTAM in Published NOTAMs or Special Notices section of Airport Facilities Directory. 38
GPS Position Accuracy n n n Selective Availability (SA) is a method by which the U. S. Department of Defense (Do. D) purposely degrades the accuracy of the civilian GPS signal (C/A code). This is typically the largest source of error in GPS. Do. D has announced that SA will be discontinued within a decade, as of March 29, 1996. When SA is active (most of the time) the Do. D guarantees that the horizontal accuracy will not be degraded beyond 100 meters (328 feet) 95% of the time, and 300 meters (984 feet) 99% of the time. The accuracy of GPS is also affected by satellite geometry, i. e. , triangulation to obtain user position is more accurate for widely-spaced satellites than for satellites clustered tightly together Other smaller sources of error are: Ù satellite ephemeris, satellite clock, ionosphere delay, troposphere delay, multipath, receiver electronics errors due to thermal noise and receiver design n Other errors of C/A code receivers are due to solar sun spot activity, potentially significant in extreme northern or southern regions, e. g. Alaska. 39
Part III -- GPS Instrument Approaches 40
Area Navigation (RNAV) Instrument Approaches n n RNAVApproaches are based on Waypoints Waypoint -- A predetermined geographical position (used for route definition and/or progress reporting purposes) that is defined by lattitude/longitude. RNAV equipment can be based on existing VOR’s , LORAN-C, or GPS, or some other navigation system. The basic idea is that a mathematical point is constructed with known coordinates, called a waypoint. The approach course is defined by waypoints instead of by traditional ground-based navaids 41
Codable vs. Non-Codable Approach Procedures n n An aircraft is not authorized to fly any IFR approach unless that Instrument Approach Procedure is retrievable from the navigation data base. Certain FAR Part 97 nonprecision instrument approaches may present an unresolvable coding situation, i. e. , an approach may be determined to be not codable by the database coding agency or the manufacturer of the navigation equipment. This means that, for a given GPS receiver, certain approaches may not be in the GPS navigation data base, due to inconsistency with the design of the receiver, e. g. , an approach may be inconsistent with algorithms used in receiver. 42
Two Types of Waypoints n Fly-by Waypoint Ù Used when aircraft should begin a turn to the next course prior to reaching the next waypoint separating the two route segments. Ù Approach waypoints (except for the Missed Approach Waypoint (MAWP) and Missed Approach Hold Waypoint (MAHWP) are normally Fly-by waypoints. Ù This turn anticipation is compensated by airspace and terrain clearance. n Fly-over Waypoint Ù New approach charts depict Fly-over waypoints as circled waypoints Ù Used when aircraft must fly over the waypoint prior to starting the turn 43
Waypoint Abbreviations in Approaches n n n n IAF -- Initial Approach Fix IF -- Intermediate Fix FAF -- Final Approach Fix IFAF -- Combination Initial Approach Fix/Final Approach Fix MAP or MAWP -- Missed Approach Point MAHP or MAHWP -- Missed Approach Hold Waypoint CF 069 -- Course Fix, e. g. , on radial 069 RW 36 -- Runway 36 threshold waypoint, often the MAP 44
Conventional vs. GPS Navigation Data n n n Slight differences may exist between the course portrayed on navigational (approach or enroute) charts and the GPS navigational display on the receiver when flying an overlay approach or along an airway. Magnetic tracks defined by VOR radials are determined by magnetic variation at the VOR; however, a GPS receiver may use the magnetic variation at the current position. This may lead to small differences in the magnetic courses. Variation in distances will occur, since GPS distance-to-waypoint values are along track (straight line) distances (ATD), while DME distances are slant range distances. ce D istan ME D GPS Distance 45
RNAV Terminology and Nav Display Angle Off Course displayed on VOR RNAV equipment, including GX 60, displays Cross Track Deviation, NOT Angle Off Course 46
Flight Plan Elements n A Flight Plan is a Sequence of waypoints Ù The Flight Plan has a direction-- there is a starting waypoint and an ending waypoint Flight Plan n n GX 60 receiver stores up to 30 flight plans, each can have up to 20 legs Name of Flight Plan on its Title Page Ù Each flight plan has a Title Page (first page) containing the Name of the Flight Plan n Active Flight Plan Ù At any time, there is one flight plan that is the Active Flight Plan Ù The Active Flight Plan may be ACTIVE or INACTIVE Ù Activate a Flight Plan by going to Title page of flight plan, and press SELECT, and press ENTER 47
GX 60 Flight Plan Elements n Active Flight Plan Location Ù In the GX 60, there is a special location for the Active Flight Plan. When a stored flight plan is Activated, the stored flight plan is copied onto the Active Flight Plan Location n Activating Flight Plan Ù Activate a Flight Plan by going to Title page of the flight plan, and press SELECT, and use large and small knobs to choose ACTIVATE, then press ENTER. Ù If your aircraft position is as shown, and you activate the Flight Plan (or reactivate it), automatic sequencing of waypoints occurs. The Active Leg becomes W 29 - ESN. The TO -waypoint becomes ESN. n Active Leg Ù At any time (when Flight Plan is Active), one leg is the Active leg, here it is W 29 --ESN. n TO-waypoint Ù At any time (when Flight Plan is Active), one waypoint is the TO-waypoint, here ESN. 48
Waypoint Sequencing in Flight Plan n n As aircraft passes each dashed line (which bisects the angle between flight plan legs) a new leg becomes the active leg, and a new waypoint becomes the current To-waypoint. Here, Active Leg is W 29 -ESN, current To-Waypoint is ESN When an instrument approach is Loaded, and Enabled, the waypoints that define the approach are automatically put on the Flight Plan waypoint sequence. The waypoints that define the instrument approach become part of the regular flight plan, and waypoints sequence as described above. 49
GX 60 Waypoint Sequencing With Duplicate Waypoints n n Consider a Flight Plan with duplicate waypoints: ANP - ESN - OXB If a Flight Plan leg contains two waypoints that are located at the same physical place (here these two points are ESN), then on passing ESN the new To-waypoint will be OXB. This situation can occur by mistake, and causes no problem. However, it commonly occurs on GPS approaches when the Initial Approach Fix (IAF) and Final Approach Fix (FAF) coincide, see for example W 29 GPS RWY 11. The coincident IAF/FAF occurs when a procedure turn must be done. In order to prevent problems with automatic waypoint sequencing during procedure turns, an OBS/HOLD button is provided to permit manual pilot intervention of waypoint sequencing. The pilot can turn waypoint sequencing ON and OFF (toggle switch) by pressing the OBS/HOLD button. 50
Entering and Activating Flight Plan in GX 60 n n n n There are two modes in the GX 60, NAV and MAP. To set up the Flight Plan, get into either of these modes by pressing NAV or MAP. Press the Smart Key FPL twice to get to the Title Page of the Active Flight Plan. Rotate the large (outer) knob one click to the left. You will see “PRESS SEL TO CEATE A NEW FLIGHT PLAN”. Press SELECT. Enter a name for the Flight Plan at the “ENTER A NEW PLAN NAME” prompt by using the Small knob for selecting the first letter of the Flight Plan name. Rotate the Large knob one click to the right, and see the second character space flashing. Enter the second letter of the Flight Plan name, using the small knob. Continue until the whole name is input. Press ENTER. See prompt “TURN SMALL KNOB TO INS WPTS OR SEL FOR OPTIONS”. Turn Small knob. Press SELECT to edit the first leg. You are ready to enter the first waypoint of the first leg. You can see that “INS? ” for Insert is flashing. Press ENTER to choose Insert. Now use the Large and Small knobs to select a desired AIRPORT, VOR, or NDB for the first waypoint. When you have made the choice, press ENTER. You are now prompted “INS? ” for inserting the second waypoint of the Flight Plan. Press ENTER to begin input. Choose your waypoint, and press ENTER. You are now prompted for the third waypoint. When you are finished inputting the waypoints for the Flight Plan, press SELECT. The Flight Plan is stored in the GX 60 (for use now or later). Now this Flight Plan must be Activated before flight. Go to the Flight Plan Title Page (where you will see the Flight Plan Name) and press SELECT. (Alternatively, start in MAP or NAV mode (by pressing MAP or NAV). Press Smart key FPL to get to the flight plans. Turn the Large knob to the left until you get to the Title Page, which contains the destination and Flight Plan name. Press SELECT to Activate this Flight Plan. ) This Flight Plan is copied to the Active Flight Plan location. 51
Entering a Flight Plan in GX 60 (cont. ) n Enter Flight Plan: ANP-CHOPS-OXB n n n n Receiver is ON Press NAV button to get into NAV Mode Press the FPL Smart Key twice to reach the Active Flight Plan Location Turn Large Knob to the left to “PRESS SEL To CREATE A NEW FLIGT PLAN” Press SELECT Enter Name of Flight Plan (which is to appear on Flight Plan Title Page), BEACH, with Small and Large Knobs Press ENTER Turn Small knob to insert waypoints Press SELECT to Edit the first Leg. See the flashing “Ins? ”, press ENTER to choose insert. Now use the large and small knob to choose AIRPORT ANP (the first waypoint). Press ENTER to input it. See flashing “INS? ” for the second waypoint. Press ENTER to input the second waypoint. Use the Small and Large knobs to choose INT CHOPS. Input the second waypoint by pressing ENTER. Now unit asks for the TO-waypoint for Leg 2. Press ENTER to insert, and use Large and Small knobs to select the waypoint AIRPORT OXB. Press ENTER to input this waypoint. Unit flashes “INS? ” to insert more waypoints, but we have input the last waypoint. Press the FPL Smart Key when done with flight plan. Turn the small knob to the left twice to get to the Title Page of this Flight Plan. See the Title “BEACH” and the destination “OXB”. Activate Flight Plan n From the Title Page of Flight Plan, see the Title “BEACH” and the destination “OXB”. Press SELECT, see “ACTIVATE? ”, then press ENTER to activate Flight Plan. The Flight Plan “BEACH” is copied to the Active Flight Plan Location, and the word “ACTIVE” indicates that it has been activated. The diamond on the right indicates that you can scroll through the active Flight Plan Legs with the Small knob. To go to MAP mode, press MAP. 52
GX 60 Flight Plan Display Features n At any time the pilot can go to the Active Flight Plan, and check which leg is the Active leg and which waypoint is the To-waypoint, pressing FPL (from NAV or MAP mode). n Active Flight Plan has all legs marked by an asterisk (*), e. g. , the second leg of the Active Flight Plan is shown as 2* Second leg of Inactive Flight Plan will be marked as 2 Active (current) Leg of the Active Flight Plan is identified by **, e. g. , when the second leg is active, it is 2**, The current TO-waypoint is the TO-waypoint on the Active Leg n n n 53
GX 60 Receiver Operation 54
GPS Standard Instrument Approach Procedure Basic “T” Design n n n Objective of the new Terminal Arrival Area (TAA) procedure is to provide a new transition method for aircraft with FMS and/or GPS navigation equipment. The basic “T” design aligns the instrument approach procedure on runway centerline with the missed approach point Missed approach point (MAP) is at runway threshold No procedure turns are needed Holding pattern at IF/FAF for pilots that elect to execute a procedure turn (PT) to meet descent gradient requirement There are many modifications of basic “T” Design (see AIM 1 -1 -37) 55
Anatomy of GPS Approaches n n n GPS Standard Instrument Approach Procedure always has a FAF, even if the original approach does not have a FAF, e. g. , see ESN NDB or GPS RWY 22 The FAF is used as a sensor to stop waypoint sequencing at the FAF At a minimum, a GPS approach consist of four waypoints: IAF - FAF - MAP - MAHP Overlay Approach Complication: Two or more of the waypoints can be physically located at the same point, e. g. , IAF and FAF may be at the same point, for example see W 29 GPS RWY 11 In some cases, three of the waypoints (IAF, MAP, and MAHP) specifying the approach are located at the same point, see for example ESN NDB or GPS RWY 22. When two or more waypoints coincide, waypoint sequencing is complicated, compared with stand alone GPS approaches, such as the basic “T”. 56
Receiver Waypoint Sequencing Schematic Graphs of Some SIAP 29 NOTE: When a holding pattern replaces the procedure turn, one turn in the pattern is required. (See p. 184 par. G, Instrument Flying Handbook, AC 61 -27 C). GPS receiver assumes one turn will be done. Sensor waypoint 57
Steps to Set Up Instrument Approach on GX 60 1. Destination Airport must be on Flight Plan, or, Press D for Direct-To Ù The last waypoint on the flight plan must be an airport (the airport for the instrument approach, not a VOR or NDB, etc. , . . ) Ù The Flight Plan must have been loaded and Activated (by pressing SELECT). Ù If there is no active Flight Plan you must press D, for direct to an Airport (not a VOR or NDB, etc. , . . ) 3. LOAD Approach Ù In NAV or MAP mode, press SELECT to select approach. (Loading an Approach removes the destination airport waypoint and puts the waypoints that define the Approach on the Flight Plan waypoint sequence. ) Ù If less than 30 nm from destination airport, then immediately get Message prompt to ENABLE APPROACH, and enter altimeter setting. Otherwise: 4. ENABLE Approach and Input Altimeter Setting 30 nm from destination airport, automatically get Message prompt to enable approach. If approach was loaded less than 30 nm from destination airport , then immediately get Message prompt to ENABLE APPROACH, and enter altimeter setting. When Approach is ENABLED, the APR annunciator light goes ON. 58
Choosing the Correct Instrument Approach n n n Each instrument approach in the GPS receiver database has a unique Initial Approach Fix (IAF). When the approach on the Instrument Approach Plate has more than one IAF, there will be multiple choices in the database associated with the different IAF’s For example: W 29 GPS RWY 29 Ù There are two IAF’s: CHOPS and PUNKN Ù Each of these two IAFs coincide with a different choice in the GPS receiver database 59
Pilot Actions Location Action n Enroute Within 30 nm of Destination Load Approach Enable Approach & enter altimeter setting (Approach annunciator, APR light turns ON) (CDI goes to 1 nm full-scale sensitivity) n IAF Verify Approach annunciator APR light is ON Verify/Set OBS/HLD: ON for Procedure Turn or Hold OFF to sequence n Aproaching FAF Verify green Approach-Active annunciator is flashing green Verify altimeter setting is entered Verify/Set OBS/HLD: OFF to sequence to MAP n At FAF (MAP becomes Active) Verify Green Approach-Active annunciator is ON OBS/HOLD goes ON (CDI goes to 0. 3 nm full-scale sensitivity) n At MAP (TO/FROM) Transition n Arriving at MAHP n If NOT landing: Press OBS/HLD OFF to cancel Approach-Active (Green Approach-Active annunciator turns OFF) (Approach Annunciator remains ON) (CDI goes to 1. 0 nm full-scale sensitivity) Verify OBS/HLD is ON Press DD to enter inbound course if needed 60
Pilot Actions on Missed Approach: DIRECT-TO Features of GX 60 n DIRECT-TO Waypoint: Press D (Once) Ù This feature allows you to select a waypoint and go DIRECT to that waypoint from your present position Ù On missed approach, use when missed approach instructions say to “go direct to” Hold fix. Example: W 00 GPS RWY 36 n SET INBOUND COURSE TO WAYPOINT: PRESS DD (press D Twice) Ù Pressing D twice allows you to enter an inbound course to a waypoint of your choice Ù On missed approach, use this for instructions such as “Climbing right turn via BAL R-135 to PUNKN”. Example W 29 GPS RWY 29 These two features are often used on the missed approach, to go to the Hold Fix (the MAP) 61
Summary of Some Automatic Sequencing Features of GX 60 During Approaches n n n On approach with procedure turn, OBS/HOLD goes ON before procedure turn (usually after crossing the IAF) OBS/HOLD goes OFF when intercepting the final approach course after procedure turn (except when IAF and FAF coincide, see for example W 29 GPS RWY 29 at PUNKN) OBS/HOLD goes ON when VECTOR TO FINAL is selected OBS/HOLD goes OFF when intercepting the final approach course (while using VECTOR TO FINAL) OBS/HOLD goes ON at FAF OBS/HOLD goes ON when using DME ARC ASSIST feature TO BE COMPETENT AT GPS APPROACHES WITH THE GX 60 YOU MUST UNDERSTAND THESE FEATURES 62
n n Special Waypoint Crossing Feature Prompts Pilot for Inbound Course When a waypoint on Hold is crossed to the FROM side the first time, the message is generated: “PUSH ENTER TO SET OBS COURSE; NAV/MAP TO EXIT”. This is used for doing Holding and also in approaches to prompt the pilot to enter the final approach course (after the procedure turn). (See manual p. 144) Example: ESN GPS RWY 22 This feature is used when: ÙCrossing the FAF out bound (in preparation for a procedure turn (e. g. , see ESN GPS RWY 22 at ESN) ÙEntering a holding pattern and crossing the Holding fix the first time out bound, in preparation to enter the Hold. Example: W 29 GPS RWY 29 at PUNKN 63
Waypoint Sequencing and Essential Pilot Actions General GX 60 Rules n n n During procedure turn -- OBS/HOLD must be ON Intercepting the Final Approach Course -- OBS/HOLD goes OFF (automatic or pilot) [Example: ESN GPS RWY 22] At FAF -- OBS/HOLD ON (always automatic) At Missed Approach Point (MAP) -- pilot always turns OBS/HOLD OFF (to permit waypoint sequencing) Entering Holding -- press D to go direct to Hold Fix (only when needed) -- press DD to set inbound course to Hold Fix (only when needed) Starting in hold, after completing missed approach, when leaving hold pilot presses OBS/HOLD OFF (to permit waypoint sequencing) 64
Repeating an Instrument Approach n n Assume that you have made an instrument approach, and you execute the missed approach. Now, assume that you are following the missed approach procedure (or are already in the missed approach Hold) When going to do an approach a second time after a missed approach: n Release Waypoint Hold Ù Press OBS/HOLD - OFF (to enable waypoint sequencing) n UNLOAD Approach (removes approach waypoints from Active Flight Plan) Ù Press SELECT, choose UNLOAD APPROACH, press ENTER n LOAD Approach Ù Input the approach again (from the beginning, starting in NAV or MAP mode) by pressing SELECT, choose the desired approach, press ENTER. Ù When prompted “ENABLE APPROACH? ”, Enable the approach by pressing ENTER, and Ù Input Altimeter setting (again) when prompted by message Ù The APPROACH LIGHT should be ON 65
Flying SIDs and STARS with GX 60 –NO! n n The GX 60 does not have SIDs (the new word: DPs)and STARs in the database. II Morrow Inc. indicates that there are no plans to put SIDs and STARs in the database. In order to fly SIDs and STARs, they must be retrievable from the database, see Draft of FAA Advisory Circular, No. AC 90 -94 A Cannot fly SIDs and STARs with the GX 60! 66
GX 60 as COMM Radio n n The GX 60 is a navigation radio and a communication radio. To access the COMM function: Ù Starting in NAV or MAP mode (by pressing NAV or MAP key) Ù Press Smart Key labeled COM. The key changes to <-> Ù The Active and Standby frequencies are labeled A and S (in front of the frequency) Ù Use small and Large knobs to select frequency Ù Press the Smart Key labeled “<->” to flip-flop frequencies. n Monitor the Standby Frequency Ù Press the Smart Key labeled MON n There are many other features -- see the manual 67
In-Flight Emergency n n n In the event of an in-flight emergency, a pilot can locate the nearest airports by Pressing NRST button Use small knob to scroll through the list of airports. The data gives distance and bearing to each airport. Select the desired airport with small knob Press D for DIRECT-TO and ENTER Use moving map or NAV mode to navigate to airport 68
PART IV -- Flying Nonprecision GPS Approaches 69
During Instrument Approaches CAUTION on Use of D and DD n n n Each flight is defined by a sequence of waypoints When an instrument approach is chosen from the database of the receiver, the waypoints defining the approach are automatically put on the waypoint sequence in the Active Flight Plan, e. g. , from ANP to W 29 with the GPS RWY 29 approach at W 29, the waypoint sequence is: ANP-PUNKN-MA 29 -PUNKN On the missed approach: Ù We often need to go Direct to the MAHP (use D on GX 60), or Ù We intercept the inbound course to the MAHP, such as “via BAL R-135 (use DD on GX 60). CAUTION: If you use D or DD, and select the missed approach course defined by a waypoint that is NOT on the Active Flight Plan waypoint sequence, the approach is automatically UNLOADED. This means that you will have to start the approach from the very beginning, including the procedure to LOAD and ENABLE approach, and input altimeter setting. See CAUTION in W 29 GPS RWY 29: PUNKN approach in this section. 70
Example GPS Approaches n 2 W 6 GPS RWY 11: JUDED (GPS stand alone approach) Leonardtown/St. Mary’s County, MD n W 29 GPS RWY 29: PUNKN (Phase III GPS Overlay Approach) Stevensville/Bay Bridge Maryland n ESN GPS RWY 22 (Phase III GPS Overlay Approach) Easton, Maryland n ACY GPS RWY 31: AVALO (Phase III GPS Overlay Approach) Atlantic City, New Jersey 71
2 W 6 GPS RWY 11 Leonardtown/St. Mary’s County, MD Features n n n n Standard “T” approach -- simplest type of approach Select the correct IAF (there are 3 IAFs) Automatic Waypoint Sequencing Automatic OBS/HOLD goes ON at FAF At MAP, Pilot use of OBS/HOLD OFF Using D on the missed approach to go direct to MAHP Setting the inbound heading to the Hold Fix 72
2 W 6 GPS RWY 11 73
2 W 6 GPS RWY 11: JUDED Procedure n n n Input Flight Plan: W 29 OTT 2 W 6, and name it ST MARY Make this Flight Plan the Active Flight Plan. Press NAV to get into the NAV mode. Press Smart Key, FPL, twice to get to the active Flight Plan. Use the large knob, turn it to the left to locate the title Page of the Flight Plan ST MARY. While on this Title Page, press SELECT and (if necessary) rotate small knob to ACTIVATE. Press ENTER. This activates the Flight Plan by copying it to the Active Flight Plan location. After takeoff, LOAD the approach procedure 2 W 6 GPS RWY 11: JUDED, which starts at the IAF JUDED. To LOAD the approach: while in NAV or MAP mode (by pressing NAV or MAP), press SELECT. Choose “LOAD APPRAOCH? ” by pressing ENTER. Scroll through the approaches with the small knob. Locate the 2 W 6 GPS RWY 11 approach that begins with JUDED as the IAF. Press ENTER. You can press MAP to return to MAP mode. Get Message “ARRIVAL AT OTT, NXT TRK 170”. Turn onto course 170. The new TO-waypoint is JUDED. At 30 nm from destination airport you get the message, “PRESS ENTER TO ENABLE APPROACH”. Press ENTER. Get message to enter the current altimeter setting. Use the Small knob to choose the correct Altimeter Setting. Press ENTER to input it. The approach is now Enabled, as indicated by the APR light being on. 74
2 W 6 GPS RWY 11: JUDED Procedure (continued 1) n n n n n Note the MSG light flashing. Press the Soft Key MSG to see the message. See Message “ARRIVAL OTT, NEXT DTK 185”. Press the Soft Key MSG to get rid of the message. Turn onto course 185. Get Message “ARRIVAL JUDED, NEXT DTK 202”. Turn onto 202 course. Get Message “ARRIVAL LEPKE, NEXT DTK 113”. Turn onto 113 course. 3 nm from the FAF, ONAFE, see the Green ACTV light flashing indicating the transition to Approach Active phase. The CDI sensitivity will scale down to 0. 3 nm, so stay close to the center of the course. Get Message “ARRIVAL ONAFE, NEXT DTK 113”. At the FAF, ONAFE, the Green ACTV Light will become steady. The OBS/HOLD will go on, since ONAFE is the FAF. If the Green ACTV Light is not on steady green at the FAF ONAFE, then discontinue the approach. After passing ONAFE, the new TO-waypoint is RW 11, which is labeled OGONY on the approach plate, and is the MAP. When passing ONAFE, the OBS/HOLD light goes ON since ONAFE is the FAF. You will execute a missed approach at RW 11. Get Message “ARRIVAL RW 11, -HOLDING-”. 75
2 W 6 GPS RWY 11: JUDED Procedure (continued 2) n n n n When the TO indicator on the CDI display turns to FROM, you are passed RW 11. Execute the missed approach. Release the OBS/HOLD. The TO-waypoint immediately becomes ONAFE, which is now the MAHP, and so the OBS/HOLD light goes ON again. The missed approach instructions are: Climb to 700, then climbing left turn to 2000 Direct ONAFE WP and Hold. Climb to 700, start the climbing left turn and press D for Direct-TO. You must verify that your Direct-To waypoint is ONAFE (if not, then choose ONAFE with large and small knobs). Press ENTER. Stay on the direct course to ONAFE Get Message “ARRIVAL ONAFE, -HOLDING-”. Passing ONAFE to the FROM side the first time produces a message: “PRESS ENTER TO SET OBS COURSE; NAV/MAP TO EXIT”. Press ENTER, and use the Large and Small knobs to set the course 112 (from the approach plate), inbound to ONAFE, the MAHP. Press ENTER. Turn to heading 262 for a tear drop entry into the Hold. Time one minute, or use the distance given to ONAFE by the GX 60. Turn inbound to ONAFE on 112 course, follow the CDI. You are established in the HOLD. The approach has ended. NOTE: All GPS Approaches begin at the IAF and end at the MAHP. 76
W 29 VOR/DME or GPS RWY 29 Stevensville/Bay Bridge Maryland n n n W 29 GPS RWY 29: PUNKN (Phase III GPS Overlay Approach) NOTE: When the IAF is PUNKN, a procedure turn is required, independent of the direction of entry (since there is a hold pattern depicted by a bold line) IAF and MAHP coincide On missed approach, use of DD to set the inbound course, BAL-135, to PUNKN. (CAUTION!) Repeat of the approach after the missed approach. Repeat the approach a third time with vectors to final approach course on the third approach 77
W 29 VOR/DME or GPS RWY 29 78
W 29 GPS RWY 29: PUNKN Procedure n n n n On this flight we go from ANP to W 29, and we do the GPS RWY 29 approach, starting at IAF PUNKN. We do the full approach twice. After the first missed approach, we are in the Hold at PUNKN, and we begin the second approach from the Hold, with the help of vectors to final approach from ATC. Below we use the same basic key stroke sequences as in the previous flight. I outline the steps, and give detail in the new sections. Whenever a message flashes, press MSG to read it and again MSG to get back to the previous display. NOTE: a procedure turn is required if the approach is started at the IAF PUNKN, so PUNKN is a HOLD WAYPOINT. Note that the IAF and FAF are both at PUNKN. Create a Flight Plan: named BAY BRG, with route ANP W 29 Activate this Flight Plan. At the Title Page of the Flight Plan, press SELECT. Press ENTER to Activate Flight Plan. Press MAP to get back into MAP mode. Begin Flight, at about 120 KTS. Immediately, LOAD the W 29 VOR/DME RWY 29 approach beginning with the IAF PUNKN, by pressing SELECT. Choose the correct approach, with PUNKN as the IAF. Since you are less than 30 nm from the destination, you immediately get the message requesting you to enable the approach. Enable the approach, and put in the altimeter setting. Fly to PUNKN. Note that the OBS/Hold is ON, since PUNKN is a Hold waypoint. There is a Hold pattern at PUNKN in bold line, indicating that one turn in the Hold is mandatory. Plan to do a tear drop entry (135 heading) into the Hold. 79
W 29 GPS RWY 29: PUNKN Procedure (continued 1) n n n After about a minute outbound, make a right turn to intercept the final approach course, BAL R-315 inbound, to the FAF MA 29. The OBS/HOLD goes off on course intercept. 3. 0 nm before PUNKN we get a flashing green ACTV light, indicating the beginning of a transition from CDI sensitivity of 1. 0 nm maximum deviation to 0. 3 nm maximum deviation. When crossing PUNKN, the OBS/HOLD goes ON, and the green ACTV light becomes solid. The current TO-waypoint becomes MA 29, which coincides with BAL DME 20. 1 If the Green ACTV Light is not on steady green at the FAF PUNKN, then discontinue the approach. Proceed on the final approach course inbound to MA 29. Get message “ARRIVAL AT MA 29”. The missed approach instructions are: “Climbing right turn to 1500 via BAL R-135 to PUNKN Int and Hold”. This means that we must intercept the course BAL R-135 to PUNKN , which is done using the DD (press D twice) function on the GX 60. Press D twice and enter the course BAL-315. At the MAP, MA 29, execute the missed approach. Press OBS/HOLD OFF, to resume sequencing. Immediately the new TO-waypoint becomes the MAHP PUNKN. Start the climbing right turn. Press D, and see that INT PUNKN is the TO-waypoint. Press D again to enter the course 135 to PUNKN. GOTCHA CAUTION: The approach plate gives the missed approach course to intercept as BAL R -135, not PUNKN-135. If you make the mistake to select BAL (instead of PUNKN) after pressing D the first time, the approach will be UNLOADED, which means that you must start the approach all over again from the beginning. Intercept the 135 course to the MAHP PUNKN. As you pass PUNKN, do a tear drop entry (heading 105) and time one minute outbound. You must press DD now to set the inbound course, 315, to PUNKN. (If you do not set the inbound course to PUNKN using DD, then you will have reverse sensing inbound to PUNKN. ) After one minute outbound, turn inbound onto course PUNKN-315. You are in the Hold, after the missed approach. The approach has ended. 80
W 29 GPS RWY 29: PUNKN Procedure (continued 2) n n n n VECTORS to the Final Approach Course We are now in the HOLD at PUNKN. ATC informs us that they will provide vectors to the final approach course for another attempt at the approach to W 29. Assume that we are outbound on a heading of 135, passing PUNKN (just north of PUNKN). We must turn the OBS/HOLD to OFF and UNLOAD the approach and reload it from the beginning. Press SELECT. With the Small knob, choose “UNLOAD APPROACH”. Press ENTER. The Towaypoint becomes the Airport W 29. The GPS RWY 29 approach waypoints have been removed from the Flight Plan waypoint sequence. Now LOAD the approach W 29 VOR/DME from the beginning. Press SELECT. With the small knob, choose LOAD APPROACH. Press ENTER. Choose the approach W 29 VOR/DME starting at PUNKN. Press ENTER. Enable the approach, and input the altimeter setting when prompted. Note that the APR light is now illuminated. Now tell the GX 60 that we are getting vectors to the final approach course. Press SELECT. With the Small knob choose “VECTOR TO FINAL? ”. Press ENTER. Note that the OBS/HOLD goes ON. The TO-waypoint is PUNKN, which is the FAF. Turn to heading 285 to intercept the final approach course. When the CDI begins to center, turn onto the inbound course to PUNKN. The OBS/HOLD goes off on course intercept. 3. 0 nm from PUNKN the green ACTV light begins to flash. At PUNKN the green ACTV light becomes solid. n If the Green ACTV Light is not on steady green at the FAF PUNKN, then discontinue the approach. n If the green ACTV light becomes solid, then continue the approach straight in and land, or do the missed approach as before. 81
ESN NDB or GPS RWY 22 n n n Previously this approach was an NDB approach without a FAF. The FAF sensor waypoint, CUTGI, has been added for the GPS approach (FAF is required for GPS) The IAF, MAP, and MAHP coincide (at ESN) Create Flight Plan: 1 N 0 -ESN LOAD approach, ENABLE approach and enter Altimeter setting 82
ESN NDB or GPS RWY 22 Description n On this trip, from Ridgely (1 N 0) to ESN, you are heading south-west. The IAF is ESN. You must cross the IAF fix, turn to intercept the outbound course, 048. When you initially cross the IAF ESN, the new TOwaypoint will become FF 22, which is a holding waypoint. This means that waypoint sequencing will be suspended (temporarily stopped), since the OBS/HOLD light is ON. You must pass CUTGI (which is FF 22), which is the sensor waypoint. Crossing CUTGI outbound will trigger the message to set your inbound course, 228, into the FAF FF 22. Go beyond CUTGI (FF 22) outbound, do the required procedure turn. Intercepting the inbound course will trigger the release of the OBS/HOLD. Now the TO-waypoint will still be FF 22. Crossing FF 22, which is now the FAF, the OBS/HOLD will go on again. Proceed to the MAP. At the MAP, release the OBS/HOLD, and the new TO-waypoint will be ESN, which is now the MAHP. Now, ESN is also a Hold waypoint (since it is a MAHP), which means that waypoint sequencing is suspended. When you pass a Hold waypoint (such as the MAHP ESN) in reverse direction, you are prompted to enter the inbound holding course, 228. Next, as you pass the MAP, you enter the Hold with a direct entry (right turn). The instrument procedure has ended in the Hold. n To repeat the approach from the HOLD, release the OBS/HOLD (to permit waypoint sequencing). UNLOAD the approach. Now LOAD it again, from the beginning. Starting from the Hold, we now do the ESN GPS RWY 22 approach again, including the missed approach again, and enter the Hold again. Finally, ATC says, you did two missed approaches, so you are not doing very well. We will give you vectors to the final approach course from the hold. Now, UNLOAD the approach. Now LOAD it again, from the beginning. Tell the GX 60 that you are getting vectors to final approach by pressing SELECT, and use the small knob to select “VECTOR TO FINAL? ” This puts the OBS/HOLD ON. When you intercept the final approach course, the OBS/HOLD goes OFF automatically. Proceed with the approach, and this time land. 83 n n
ESN NDB or GPS RWY 22 84
ESN GPS RWY 22 Procedure n n n n 1. Load Flight Plan 2. Activate Flight Plan 3. Increase your speed to about 100 KTS using the up and down arrow keys. Use left and right keys to turn airplane. 4. Press SELECT to LOAD Approach ESN GPS RWY 22. 5. Receive message, “ENABLE APPROACH? ”, Press ENTER to enable. Receive message requesting the altimeter setting. Use small and large knobs to input altimeter setting. Press ENTER. Since the approach is enabled, the APR light is ON. 6. Fly south west from 1 N 0 to ESN waypoint. 7. Cross over ESN, get message “ARRIVAL AT ESN NEXT DTK 049”. The OBS/HOLD light goes ON. The new waypoint becomes FF 22, which is CUTGI on the approach plate. 8. Turn to the right to intercept the ESN 049 outbound course. Track outbound on course 049. Time two minutes. 9. You must pass the sensor waypoint FF 22. Get message, “Arrival at FF 22 -HOLDING-”. Press the Smart Key labeled MESS to see the message. Press the Smart Key labeled MESS to go back to the previous display. 10. See message, “PRESS ENTER TO SET OBS COURSE, NAV/MAP TO EXIT”. Press ENTER and set the INBOUND COURSE to FF 22 228”, based on the approach plate. Press ENTER. This sets up the GX 60 to release the Hold when you intercept the final approach course. 11. When two minutes expires, turn to heading 003 for the procedure turn. Time one minute outbound. Make the turn to heading 183, to intercept the inbound course. 12. Get message, “COURSE INTERCEPT, DTK 228”. Turn to 228 course, inbound to FF 22. 13. At 3. 0 nm out from the FAF (which is now FF 22), you will see the green ACTV light start flashing, indicating that the Transition to Approach has begun and that the CDI will begin to scale down from 1. 0 to 0. 3 nm full scale deflection. The To-waypoint is still FF 22. Get message “ARRIVAL AT FF 22, NXT DTK 229”. At FF 22 the CDI has completed its scaling down to 0. 3 nm max deviation, so you must be close to the center of course. 85
ESN GPS RWY 22 Procedure (cont. ) n n n 14. When you pass the FAF FF 22, the green ACTV light goes solid, indicating that you are now in the Approach Active Operation. NOTE: IF THE ACTIVE (GREEN) LIGHT IS NOT ON STEADY AT THE FAF DO NOT CONTINUE THE APPROACH. 15. Get message “Arrival at ESN -HOLDING-”. This indicates that ESN is a Holding waypoint, so waypoint sequencing has stopped. 16. At MAP see the TO indication on the CDI display turn to a FROM. Now do the missed approach. 17. Release OBS/HOLD at the MAP, and turn into the holding pattern (right turn) to approximately heading 048. 18. When crossing to the FROM side of the Holding waypoint ESN, the following message is triggered: “PRESS ENTER TO SET OBS COURSE, NAV/MAP TO EXIT”. Press ENTER. Set the OBS course to 228. Press ENTER. 19. Time one minute outbound. Turn inbound in the Hold. You are established in the Hold. The approach has ended. You can go around as many times as you wish in the Hold. REPEATING THE APPROACH FROM THE HOLD 20. Release the OBS/HOLD. 21. Unload the approach by pressing SELECT, and use the small knob to choose “UNLOAD the APPROACH”. Press ENTER. This removes the waypoints from the Flight Plan waypoint sequence. 22. LOAD the approach ESN GPS RWY 22 again and enable it. Enter the altimeter setting, press ENTER. 23. You are now ready to fly the full approach again from the very beginning. You must go to ESN and then intercept the out bound course 049. Do the whole procedure turn, and turn inbound on the final approach course. This means that you must follow steps 7 to 19 above. We assume that you have done this. Now you are missed approach again, and you enter the Hold pattern. 86
ESN GPS RWY 22 Procedure (cont. ) n n n n VECTORS TO FINAL APPROACH Assuming that you have performed the above two approaches, and you are in the Hold, after your second missed approach. This time you will get vectors to final from ATC. You must unload, reload and enable the whole approach, as follows: 24. Release OBS/HOLD. 25. Unload the approach by pressing SELECT, and use the small knob to choose “UNLOAD the APPROACH”. Press ENTER. This removes the waypoints from the Flight Plan waypoint sequence. 26. LOAD the approach ESN GPS RWY 22 again and enable it. Enter the altimeter setting, press ENTER. 27. You must tell the GX 60 that you are getting vectors to final. Press SELECT, and use the small knob to choose “VECTOR TO FINAL”. Press ENTER. The OBS/HOLD is now ON. The current TO-waypoint is FF 22. Waypoint sequencing is suspended. Intercept the final approach course and waypoint sequencing will automatically resume. You must be vectored onto the final approach course outside the FAF, which is FF 22. On course intercept to the final approach course, get message “COURSE INTERCEPT NXT DTK 229”. Turn inbound on the 229 course. The OBS/HOLD light now goes OFF, indicating that normal waypoint sequencing is resuming. The approach proceeds as before, starting with number 13 above. This time, execute the approach and land. 87
ACY GPS RWY 31: AVALO n n DME Arc procedure, using the GX 60 DME ARC ASSIST FEATURE Selection of procedure with correct IAF Missed approach using DD to intercept ACY R 090 Use of DD to set inbound course to the MAHP 88
ACY GPS RWY 31 89
ACY GPS RWY 31: AVALO Procedure n n n n Create and Activate a Flight Plan from Ocean City, New Jersey (26 N) to Atlantic City, New Jersey(ACY). Begin the flight and immediately LOAD and ENABLE the approach, ACY VOR RWY 31: AVALO, which begins at IAF AVALO. The APR light should be ON. Use the CDI and moving map to fly direct to AVALO. See message “ARRIVAL: AVALO, DME NXT-USE ARC ASSIST? , ENTER” Press ENTER. Make sure that the you see LEFT ARC, DTK XXX, REF: ACY VOR, 11. 0 NM”, which says that this will be a LEFT ARC, around the reference point ACY. If you see RIGHT, then use the Small knob to choose LEFT. If You do not see ACY as the reference point, then use the Small knob to select it. As you fly, use the heading shown by DTK XXX, where XXX is the no-wind heading that is perpendicular to the radius of the DME Arc at each point of the Arc. Monitor the distance from the reference waypoint, ACY, to stay close to the 11. 0 NM arc. During the DME ARC, the OBS/HOLD is ON. Receive message that you are arriving at BAZES. Turn inbound onto the ACY R-122. 3. 0 nm from FAF BERGR the green ACTV light begins to flash. Passing BERGR, the green ACTV light goes ON solid. The OBS/HOLD goes ON at FAF BERGR. If the Green ACTV Light is not on steady green at the FAF BERGR, then discontinue the approach. At the MAP, turn OBS/HOLD OFF, and follow the missed approach instructions. Climbing right turn to 2300 via ACY R 090 to SMITS Int/11 DME and Hold. Press D and see INT SMITS. Press ENTER. Press D again to set the inbound course to SMITS. The GPS database comes up with course 091 to SMITS. Press ENTER. At SMITS, do a tear drop entry. Now set the inbound course to SMITS, 270. Press D, see INT SMITS. Press D and set 270 as the inbound course of the HOLD, from the approach plate. Turn inbound onto course SMITS-270. You are now established in the Hold. The approach has ended. 90
Summary of GX 60 Navigation Procedures Navigate DIRECT to WAYPOINT D WAYPOINT HOLDING D WAYPOINT + OBS HOLD ON, Enter HOLDING COURSE (in message) after crossing WAYPOINT Intercept Course TO a WAYPOINT or Intercept VOR Radial Inbound DD WAYPOINT (works for any waypoint) Intercept Course FROM a WAYPOINT or Intercept VOR Radial Outbound D WAYPOINT + HOLD OBS ON, then DD WAYPOINT and enter the COURSE Edit Active Flight Plan press NAV + FPL, edit with SELECT 91
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PART V -- Flying Approaches with Garmin 430 93
Garmin GNS 430 94
Features of GNS 430 • The GNS 430 contains several receivers: • GPS • VOR • Localizer • Glideslope • Certificated for Enroute, Terminal and Approach Operations • Types of Approaches Permitted: • Non-precision standalone GPS approaches and overlay approaches – using GPS receiver • RNAV approaches – using GPS receiver • VOR approaches – using VOR receiver • ILS approaches – using Localizer/Glideslope receiver • Expected to become WAAS capable when WAAS is approved for IFR • Can fly DPs and STARs, since they are in the database 95
Summary of GNS 430 Navigation Procedures Navigate DIRECT to WAYPOINT: press D + select waypoint + ENT HOLDING: D + press OBS + rotate HSI OBS to set inbound course Select Active Leg of Active Flight Plan: FPL + Select TO Waypoint + DD Intercept Course TO a WAYPOINT or Intercept VOR Radial Inbound D + input course into CRS window Better Alternative: D + press OBS + set course using OBS on HSI Intercept Course FROM a WAYPOINT or Intercept VOR Radial Outbound D + input course into CRS window + OBS (to see course line) Better Alternative: D + press OBS + set course using OBS on HSI Activate a specific leg of the active flight plan: on active flight plan, select the TO WAYPOINT and press DD Edit Active Flight Plan press FPL, push cursor to select, use CLR and small/big knobs 96
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Approaches Flyable with the GPS Receiver in the GNS 430 98
Illuminating Exercise Compare Waypoint Sequencing on GNS 430 and GX 60 1. Load flight plan; FME-W 29 -ESN, and activate it. (NOTE: The GNS 430 uses international identifiers KFME, and KESN for most big airports. ) 2. Fly from FME about half-way to W 29. Then use D to go direct to SBY. 3. Look at the Active Flight Plan for both GX 60 and GNS 430. 4. The GX 60 inserts an additional leg, labeled DIRECT-SBY, into the Active Flight Plan. 5. The GNS 430 puts the direct leg into a separate window (above the main flight plan waypoints). 6. CONCLUSION: The GNS 430 uses more sophisticated internal algorithms to control waypoint sequencing than the GX 60. 7. The GNS 430 relies heavily on the idea of re-activating a given leg of the main flight plan below the DIRECT window. (Note: the active leg is shown by the big magenta arrow). 99
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World Wide Web Sites for more information n FAA Site on GPS and Satellite navigation http: //gps. faa. gov/ n FAA Description of WAAS and LAAS http: //gps. faa. gov/Programs/WAAS/waas. htm n Excellent detailed tutorial on GPS from: Peter H. Dana, The Geographer's Craft Project, Department of Geography, The University of Colorado at Boulder, at web site: http: //www. colorado. Edu/geography/gcraft/notes/gps_f. html 101
References n n n n n MAIN REFERENCES FOR PILOTS Federal Aviation Regulations & Aeronautical Information Manual, ASA-02 -FR-AM-BK, Aviation Supplies and Academics, Inc. , Newcastle WA (2002). “Guidelines for Operators Using Global Positioning System Equipment for IFR En Route and Terminal Operations and for Nonprecision Instrument Approaches in the U. S. National Airspace System”, Draft of FAA Advisory Circular, No. AC 90 -94 A. Instrument Flying Handbook, FAA-H-8083 -15, U. S. Department of Transportation, Federal Aviation Administration, Flight Standards Office, (2002). D. De Remer and D. W. Mc. Lean, “Global Navigation for Pilots: International Flight Techniques & Procedures”, Aviation Supplies Academics, Inc. , Newcastle, Washington, (1993). B. Clarke, “Aviators Guide to GPS”, 2 nd Edition, Mc. Graw-Hill Inc. , 1995. HISTORY OF SATELLITE NAVIGATION B. W. Parkinson, T. Stansell, R. Beard, and K. Gromov, “A History of Satellite Navigation”, Navigation: J. of the Institute of Navigation, 42, 109 (1995). Technical References on GPS B. W. Parkinson and J. J. Spilker, eds. , “Global Positioning System: Theory and Applications”, vol. I and II (P. Zarchan, editor-in-chief), Progress in Astronautics and Aeronautics, vol. 163 and 164, Amer. Inst. Aero. Astro. , Washington, DC (1996). E. D. Kaplan, “ Understanding GPS: Principles and Applications”, Mobile Communications Series, Artech House, Boston (1996). B. Hofmann-Wellenhof, H. Lichtenegger, and J. Collins, “Global Positioning System Theory and Practice”, Springer-Verlag, New York (1993). 102
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