GPS APPROACH (RWOP 917.)
A Global Positioning System (GPS) approach is a non-precision instrument approach based on satellite transmitted positioning information received by on-board equipment and not dependent on ground-based navigation aids.
B. Procedures (full approach)
* Before reaching the IAF:
1. OBTAIN WEATHER, ALTIMETER, DUTY RUNWAY AND WINDS (WAR) OR ATIS/ASOS/AWOS.
2. NAVAIDS: LOAD APPROACH INTO ACTIVE FLIGHT PLAN:
A. SELECT AIRPORT IDENTIFIER (APT PAGE, TOP OF RIGHT
PAGE)
B. SELECT APPROACH
C. LOAD APPROACH (INTO FPL 0)
D. SELECT APPROPRIATE MODE and NAV SOURCE ON GPS PANEL
E. TUNE AND ID ANY AVAILABLE BACK-UP NAVAIDS
3. CHECK FOR OTHER "TRANSITION" POINTS (ie. STEP DOWN ALTITUDE FIXES) THAT ARE PUBLISHED ON THE APPROACH PLATE BUT NOT INCLUDED AS A WAYPOINT IN THE GPS APPROACH OBTAINED FROM THE DATABASE.
4. BRIEF APPROACH AND CO-PILOT DUTIES.
5. OBTAIN APPROACH CLEARANCE.
(*PRIOR TO IAF ENSURE APPROACH IS ARMED ON GPS PANEL)
*At the IAF:
1. TIME. NOTE TIME AT IAF.
2. TURN. TURN OUTBOUND ON PROCEDURE TURN OR TOWARDS NEXT WAYPOINT OF THE APPROACH AS APPROPRIATE.
3. TIME. N/R
4. TRANSITION. DECELERATE TO FINAL APPROACH SPEED OF 90 KIAS, DESCEND AS REQUIRED, COMPLETE LANDING CHECKLIST.
5. TWIST. SET DESIRED COURSE IN HSI/CDI AND ENSURE APPROPRIATE MODE (OBS/LEG) ON GPS PANEL. CHECK THAT GPS HAS SEQUENCED TO NEXT WPT.
6. TALK. MAKE VOICE REPORT AS REQUIRED.
7. EXECUTE APPROACH AS DEPICTED ON THE APPROACH PLATE, MAKE VOICE REPORTS AS DIRECTED, PROCEED TO MAP.
*At each waypoint:
1. TIME. N/R
2. TURN. TURN AS REQUIRED TO INTERCEPT SUBSEQUENT LEGS OF THE APPROACH.
3. TIME. N/R
4. TRANSITION. DESCEND TO NEXT INTERMEDIATE ALTITUDE OR MDA AS APPLICABLE. REVIEW LANDING CHECKLIST COMPLETE (GIVE CONSIDERATION TO LIGHTING CONFIGURATION INSIDE FAF.)
5. TWIST. SET DESIRED COURSE IN HSI/CDI, ENSURE LEG MODE (WHEN INBOUND TO FAF), CHECK THAT GPS HAS SEQUENCED TO NEXT WPT ON APPROACH.
6. TALK. MAKE VOICE REPORT AS REQUIRED/DIRECTED.
*If missed approach is required:
1. SET REQUIRED 70 KT CLIMB/100 KT CRUISE POWER.
2. SET REQUIRED 70 KT CLIMB/100 KT CRUISE NOSE ATTITUDE. (CHECK IVSI / ALTIMETER FOR POSITIVE CLIMB INDICATIONS).
3. TURN SEARCHLIGHT OFF.
4. TURN TO COMPLY WITH MISSED APPROACH OR CLIMBOUT INSTRUCTIONS. HAVE CO-PILOT MANUALLY SEQUENCE GPS (DIRECT-TO PBS) TO NEXT WPT REQUIRED FOR MISSED APPROACH.
5. TALK. REPORT MISSED APPROACH/EXECUTING CLIMBOUT INSTRUCTIONS, REASON FOR MISSED APPROACH(IF APPLICABLE) AND INTENTIONS AS SOON AS PRACTICABLE.
C. Amplification and technique
1. The approach to be executed must be entered into the active flight plan by selecting from the list of available approaches in the GPS Airport database (only 1 approach can be entered into the active FPL at a time).
2. CDI/HSI must be in the OBS mode for procedure turns, holding patterns and RVFAC until inbound on a portion of the approach when LEG mode should be selected (TWIST HSI/CDI to appropriate course and ensure GPS is in LEG mode)
3. If being radar vectored to final use the HSI/CDI in OBS mode until established on the approach course then switch to the LEG prior to arriving at the FAF.
4. During vectors to final it is imperative that the pilot stay oriented so that the next WPT that the aircraft will fly to on the approach is the active WPT after intercepting final.
5. If holding at a WPT remain in OBS mode. When cleared for the approach and inbound to the WPT, switch to LEG mode in order to enable the GPS unit to sequence through the waypoints that constitute the approach.
D. SELECT APPROPRIATE MODE and NAV SOURCE ON GPS PANEL
E. TUNE AND ID ANY AVAILABLE BACK-UP NAVAIDS
3. CHECK FOR OTHER "TRANSITION" POINTS (ie. STEP DOWN ALTITUDE FIXES) THAT ARE PUBLISHED ON THE APPROACH PLATE BUT NOT INCLUDED AS A WAYPOINT IN THE GPS APPROACH OBTAINED FROM THE DATABASE.
4. BRIEF APPROACH AND CO-PILOT DUTIES.
5. OBTAIN APPROACH CLEARANCE.
(*PRIOR TO IAF ENSURE APPROACH IS ARMED ON GPS PANEL)
*At the IAF:
1. TIME. NOTE TIME AT IAF.
2. TURN. TURN OUTBOUND ON PROCEDURE TURN OR TOWARDS NEXT WAYPOINT OF THE APPROACH AS APPROPRIATE.
3. TIME. N/R
4. TRANSITION. DECELERATE TO FINAL APPROACH SPEED OF 90 KIAS, DESCEND AS REQUIRED, COMPLETE LANDING CHECKLIST.
5. TWIST. SET DESIRED COURSE IN HSI/CDI AND ENSURE APPROPRIATE MODE (OBS/LEG) ON GPS PANEL. CHECK THAT GPS HAS SEQUENCED TO NEXT WPT.
6. TALK. MAKE VOICE REPORT AS REQUIRED.
7. EXECUTE APPROACH AS DEPICTED ON THE APPROACH PLATE, MAKE VOICE REPORTS AS DIRECTED, PROCEED TO MAP.
*At each waypoint:
1. TIME. N/R
2. TURN. TURN AS REQUIRED TO INTERCEPT SUBSEQUENT LEGS OF THE APPROACH.
3. TIME. N/R
4. TRANSITION. DESCEND TO NEXT INTERMEDIATE ALTITUDE OR MDA AS APPLICABLE. REVIEW LANDING CHECKLIST COMPLETE (GIVE CONSIDERATION TO LIGHTING CONFIGURATION INSIDE FAF.)
5. TWIST. SET DESIRED COURSE IN HSI/CDI, ENSURE LEG MODE (WHEN INBOUND TO FAF), CHECK THAT GPS HAS SEQUENCED TO NEXT WPT ON APPROACH.
6. TALK. MAKE VOICE REPORT AS REQUIRED/DIRECTED.
*If missed approach is required:
1. SET REQUIRED 70 KT CLIMB/100 KT CRUISE POWER.
2. SET REQUIRED 70 KT CLIMB/100 KT CRUISE NOSE ATTITUDE. (CHECK IVSI / ALTIMETER FOR POSITIVE CLIMB INDICATIONS).
3. TURN SEARCHLIGHT OFF.
4. TURN TO COMPLY WITH MISSED APPROACH OR CLIMBOUT INSTRUCTIONS. HAVE CO-PILOT MANUALLY SEQUENCE GPS (DIRECT-TO PBS) TO NEXT WPT REQUIRED FOR MISSED APPROACH.
5. TALK. REPORT MISSED APPROACH/EXECUTING CLIMBOUT INSTRUCTIONS, REASON FOR MISSED APPROACH(IF APPLICABLE) AND INTENTIONS AS SOON AS PRACTICABLE.
C. Amplification and technique
1. The approach to be executed must be entered into the active flight plan by selecting from the list of available approaches in the GPS Airport database (only 1 approach can be entered into the active FPL at a time).
2. CDI/HSI must be in the OBS mode for procedure turns, holding patterns and RVFAC until inbound on a portion of the approach when LEG mode should be selected (TWIST HSI/CDI to appropriate course and ensure GPS is in LEG mode)
3. If being radar vectored to final use the HSI/CDI in OBS mode until established on the approach course then switch to the LEG prior to arriving at the FAF.
4. During vectors to final it is imperative that the pilot stay oriented so that the next WPT that the aircraft will fly to on the approach is the active WPT after intercepting final.
5. If holding at a WPT remain in OBS mode. When cleared for the approach and inbound to the WPT, switch to LEG mode in order to enable the GPS unit to sequence through the waypoints that constitute the approach.
NOTE: If executing a procedure turn following holding remain in OBS until procedure turn inbound.
6. When switching from OBS to LEG mode and vice versa always ensure you are inbound to the desired WPT.
6. When switching from OBS to LEG mode and vice versa always ensure you are inbound to the desired WPT.
NOTE: Switching modes sometimes causes the KLN-900 to cycle to the next WPT in the approach sequence.
7. Prior to 2NM from FAF ensure GPS is in LEG mode. If GPS doesn't cycle to ACTIVE mode (ACTV) automatically, do not continue to MDA and contact ATC with intentions.
D. Common errors and safety notes
1. When being radar vectored to final HSI/CDI should remain in OBS mode. If LEG is selected the course from the aircraft to the active WPT will be locked into the HSI/CDI and may not be the FAC.
2. RAIM (receiver autonomous integrity monitoring) must be available to commence a GPS approach. A flashing Message indicator may be an indication of RAIM nonavailability.
3. Some published approaches that are parallel to ground based NAVAID-based approaches may contain transition points that do not have corresponding waypoints in the associated GPS approach. It is the responsibility of the pilot to identify these points and apply them to any GPS approach to be commenced by fixing their position relative to other waypoints that are contained within the GPS database. Note that DME will always count down to the active waypoint when inbound on approach.
4. The GPS unit will not automatically sequence to any waypoints required for a missed approach procedure. Automatic sequencing will cease at the MAP. If a missed approach is required, the pilot must manually sequence the unit to the missed approach WPT (Simply press the "direct to" key followed by the "enter" key, the default WPT will be the missed approach WPT following an approach that terminates at the MAP).
5. Not switching from OBS to LEG prior to FAF.
6. Not ensuring approach is armed within 30 NM of airfield.
7. Not checking that approach is ACTIVE at FAF.
8. Mistaking CDI/HSI scale change (Enroute to ARM to ACTV) for actual deviations and subsequently making unneeded or unnecessarily large corrections.
B. Localizer procedures
C. ILS procedures
D. Glideslope failure
5. If a glideslope indicator disappears on the CDI/HSI during the approach, descend no lower than published localizer minima, or if not published, no lower than circling minima for your category aircraft. If course deviation bar is fully deflected when inside of final approach fix and runway is not in sight, execute missed approach.
F. Precision minima
7. Prior to 2NM from FAF ensure GPS is in LEG mode. If GPS doesn't cycle to ACTIVE mode (ACTV) automatically, do not continue to MDA and contact ATC with intentions.
D. Common errors and safety notes
1. When being radar vectored to final HSI/CDI should remain in OBS mode. If LEG is selected the course from the aircraft to the active WPT will be locked into the HSI/CDI and may not be the FAC.
2. RAIM (receiver autonomous integrity monitoring) must be available to commence a GPS approach. A flashing Message indicator may be an indication of RAIM nonavailability.
3. Some published approaches that are parallel to ground based NAVAID-based approaches may contain transition points that do not have corresponding waypoints in the associated GPS approach. It is the responsibility of the pilot to identify these points and apply them to any GPS approach to be commenced by fixing their position relative to other waypoints that are contained within the GPS database. Note that DME will always count down to the active waypoint when inbound on approach.
4. The GPS unit will not automatically sequence to any waypoints required for a missed approach procedure. Automatic sequencing will cease at the MAP. If a missed approach is required, the pilot must manually sequence the unit to the missed approach WPT (Simply press the "direct to" key followed by the "enter" key, the default WPT will be the missed approach WPT following an approach that terminates at the MAP).
5. Not switching from OBS to LEG prior to FAF.
6. Not ensuring approach is armed within 30 NM of airfield.
7. Not checking that approach is ACTIVE at FAF.
8. Mistaking CDI/HSI scale change (Enroute to ARM to ACTV) for actual deviations and subsequently making unneeded or unnecessarily large corrections.
B. Localizer procedures
C. ILS procedures
D. Glideslope failure
5. If a glideslope indicator disappears on the CDI/HSI during the approach, descend no lower than published localizer minima, or if not published, no lower than circling minima for your category aircraft. If course deviation bar is fully deflected when inside of final approach fix and runway is not in sight, execute missed approach.
F. Precision minima
Approach Criteria for Single-Piloted Aircraft (OPNAV 3710.7R 5.3.4.3)
An instrument approach shall not be commenced if the reported weather is below published minimums for the type approach being conducted. …. Absolute minimums for a single-piloted aircraft executing a precision approach are 200-foot ceiling/height above touchdown (HAT) and visibility 1/2-statute-mile / 2,400 feet RVR or published minimums, whichever is higher.
1. The lowest authorized ILS minimums, with all required ground and airborne systems components operative, are
(a) Category I Decision Height (DH) 200 feet and Runway Visual Range (RVR) 2,400 feet (with touchdown zone and centerline lighting, RVR 1800 feet).
G. CAT II ILS
Why Brief this? Well, I would guess that it is to show us that we cannot shoot CAT II ILS approaches because we don’t have either the installed equipment or the authorization. If you happen to know update this gouge.
CATEGORY II OPERATIONS EQUIPMENT
The instruments and equipment listed in this section must be installed in each aircraft operated in a Category II operation. This section does not require duplication of instruments and equipment required by §91.205 or any other provisions of this chapter.
(a) Group I.
(1) Two localizer and glide slope receiving systems. Each system must provide a basic ILS display and each side of the instrument panel must have a basic ILS display. However, a single localizer antenna and a single glide slope antenna may be used.
(2) A communications system that does not affect the operation of at least one of the ILS systems.
(3) A marker beacon receiver that provides distinctive aural and visual indications of the outer and the middle markers.
(4) Two gyroscopic pitch and bank indicating systems.
(5) Two gyroscopic direction indicating systems.
(6) Two airspeed indicators.
(7) Two sensitive altimeters adjustable for barometric pressure, each having a placarded correction for altimeter scale error and for the wheel height of the aircraft. After June 26, 1979, two sensitive altimeters adjustable for barometric pressure, having markings at 20-foot intervals and each having a placarded correction for altimeter scale error and for the wheel height of the aircraft.
(8) Two vertical speed indicators.
(9) A flight control guidance system that consists of either an automatic approach coupler or a flight director system. A flight director system must display computed information as steering command in relation to an ILS localizer and, on the same instrument, either computed information as pitch command in relation to an ILS glide slope or basic ILS glide slope information. An automatic approach coupler must provide at least automatic steering in relation to an ILS localizer. The flight control guidance system may be operated from one of the receiving systems required by subparagraph (1) of this paragraph.
(10) For Category II operations with decision heights below 150 feet either a marker beacon receiver providing aural and visual indications of the inner marker or a radio altimeter.
Required Equipment for Night Flight (NATOPS 4.21)
1. All Exterior lights
2. All Instrument and Circuit Breaker panel lights
3. Operating Communications Radio
4. Attitude Gyro
5. Radar Altimeter
Night and Instrument Flights (NATOPS 5.5.3)
A flashlight shall be carried in the aircraft.
Introduce
A. GPS approach (min 2)
B. Localizer approach (min 1)
C. ILS approach (min 2)
Practice
A. Instrument takeoff (ITO)
B. Standard instrument departure (SID)
C. ASR
D. Enroute navigation/fuel consumption checks
A. ILS OPERATION
INSTRUMENT LANDING SYSTEM (ILS)
a. General
1. The ILS is designed to provide an approach path for exact alignment and descent of an aircraft on final approach to a runway.
2. The ground equipment consists of two highly directional transmitting systems and, along the approach, three (or fewer) marker beacons. The directional transmitters are known as the localizer and glide slope transmitters.
3. The system may be divided functionally into three parts:
(a) Guidance information localizer, glide slope
(b) Range information marker beacon, DME
(c) Visual information approach lights, touchdown and centerline lights, runway lights
4. Compass locators located at the Outer Marker (OM) or Middle Marker (MM) may be substituted for marker beacons. DME, when specified in the procedure, may be substituted for the OM.
5. Where a complete ILS system is installed on each end of a runway; (i.e., the approach end of Runway 4 and the approach end of Runway 22) the ILS systems are not in service simultaneously.
b. Localizer
1. The localizer transmitter operates on one of 40 ILS channels within the frequency range of 108.10 to 111.95 MHz. Signals provide the pilot with course guidance to the runway centerline.
2. The approach course of the localizer is called the front course and is used with other functional parts, e.g., glide slope, marker beacons, etc. The localizer signal is transmitted at the far end of the runway. It is adjusted for a course width (full scale fly-left to a full scale fly-right) of 700 feet at the runway threshold.
3. The course line along the extended centerline of a runway, in the opposite direction to the front course is called the back course.
CAUTION: Unless the aircraft's ILS equipment includes reverse sensing capability, when flying inbound on the back course it is necessary to steer the aircraft in the direction opposite the needle deflection when making corrections from off-course to on-course. This "flying away from the needle" is also required when flying outbound on the front course of the localizer. DO NOT USE BACK COURSE SIGNALS for approach unless a BACK COURSE APPROACH PROCEDURE is published for that particular runway and the approach is authorized by ATC.
4. Identification is in International Morse Code and consists of a three-letter identifier preceded by the letter I (··) transmitted on the localizer frequency.
5. The localizer provides course guidance throughout the descent path to the runway threshold from a distance of 18 NM from the antenna between an altitude of 1,000 feet above the highest terrain along the course line and 4,500 feet above the elevation of the antenna site. Proper off-course indications are provided throughout the following angular areas of the operational service volume:
(a) To 10 degrees either side of the course along a radius of 18 NM from the antenna, and
(b) From 10 to 35 degrees either side of the course along a radius of 10 NM.
6. Unreliable signals may be received outside these areas.
c. Localizer-type Directional Aid
1. The Localizer-type Directional Aid (LDA) is of comparable use and accuracy to a localizer but is not part of a complete ILS. The LDA course usually provides a more precise approach course than the similar Simplified Directional Facility (SDF) installation, which may have a course width of 6 or 12 degrees.
2. The LDA is not aligned with the runway. Straight-in minimums may be published where alignment does not exceed 30 degrees between the course and runway. Circling minimums only are published where this alignment exceeds 30 degrees.
d. Glide Slope/Glide Path
1. The UHF glide slope transmitter, operating on one of the 40 ILS channels within the frequency range 329.15 MHz, to 335.00 MHz radiates its signals in the direction of the localizer front course. The term "glide path" means that portion of the glide slope that intersects the localizer.
CAUTION: False glide slope signals may exist in the area of the localizer back course approach which can cause the glide slope flag alarm to disappear and present unreliable glide slope information. Disregard all glide slope signal indications when making a localizer back course approach unless a glide slope is specified on the approach and landing chart.
2. The glide slope transmitter is located between 750 feet and 1,250 feet from the approach end of the runway (down the runway) and offset 250 to 650 feet from the runway centerline. It transmits a glide path beam 1.4 degrees wide (vertically). The signal provides descent information for navigation down to the lowest authorized decision height (DH) specified in the approved ILS approach procedure. The glide path may not be suitable for navigation below the lowest authorized DH and any reference to glide path indications below that height must be supplemented by visual reference to the runway environment. Glide paths with no published DH are usable to runway threshold.
3. The glide path projection angle is normally adjusted to 3 degrees above horizontal so that it intersects the MM at about 200 feet and the OM at about 1,400 feet above the runway elevation. The glide slope is normally usable to the distance of 10 NM. However, at some locations, the glide slope has been certified for an extended service volume which exceeds 10 NM.
4. Pilots must be alert when approaching the glide path interception. False courses and reverse sensing will occur at angles considerably greater than the published path.
5. Make every effort to remain on the indicated glide path.
CAUTION: Avoid flying below the glide path to assure obstacle/terrain clearance is maintained.
6. The published glide slope threshold crossing height (TCH) DOES NOT represent the height of the actual glide path on course indication above the runway threshold. It is used as a reference for planning purposes which represents the height above the runway threshold that an aircraft's glide slope antenna should be, if that aircraft remains on a trajectory formed by the four-mile-to-middle marker glide path segment.
7. Pilots must be aware of the vertical height between the aircraft's glide slope antenna and the main gear in the landing configuration and, at the DH, plan to adjust the descent angle accordingly if the published TCH indicates the wheel crossing height over the runway threshold may not be satisfactory. Tests indicate a comfortable wheel crossing height is approximately 20 to 30 feet, depending on the type of aircraft.
e. Distance Measuring Equipment (DME)
1. When installed with the ILS and specified in the approach procedure, DME may be used:
(a) In lieu of the OM.
(b) As a back course (BC) final approach fix (FAF).
(c) To establish other fixes on the localizer course.
2. In some cases, DME from a separate facility may be used within Terminal Instrument Procedures (TERPS) limitations:
(a) To provide ARC initial approach segments.
(b) As a FAF for BC approaches.
(c) As a substitute for the OM.
f. Marker Beacon
1. ILS marker beacons have a rated power output of 3 watts or less and an antenna array designed to produce an elliptical pattern with dimensions, at 1,000 feet above the antenna, of approximately 2,400 feet in width and 4,200 feet in length. Airborne marker beacon receivers with a selective sensitivity feature should always be operated in the "low" sensitivity position for proper reception of ILS marker beacons.
2. Ordinarily, there are two marker beacons associated with an ILS, the OM and MM. Locations with a Category II ILS also have an inner marker (IM). When an aircraft passes over a marker, the pilot will receive the following indications:
MARKER PASSAGE INDICATOR
MARKER CODE LIGHT
OM - - - BLUE
MM ·-·- AMBER
IM ···· WHITE
BC ·· ·· WHITE
(a) The OM normally indicates a position at which an aircraft at the appropriate altitude on the localizer course will intercept the ILS glide path.
(b) The MM indicates a position approximately 3,500 feet from the landing threshold. This is also the position where an aircraft on the glide path will be at an altitude of approximately 200 feet above the elevation of the touchdown zone.
(c) The inner marker (IM) will indicate a point at which an aircraft is at a designated decision height (DH) on the glide path between the MM and landing threshold.
3. A back course marker normally indicates the ILS back course final approach fix where approach descent is commenced.
g. Compass Locator
1. Compass locator transmitters are often situated at the MM and OM sites. The transmitters have a power of less than 25 watts, a range of at least 15 miles and operate between 190 and 535 kHz. At some locations, higher powered radio beacons, up to 400 watts, are used as OM compass locators. These generally carry Transcribed Weather Broadcast (TWEB) information.
2. Compass locators transmit two letter identification groups. The outer locator transmits the first two letters of the localizer identification group, and the middle locator transmits the last two letters of the localizer identification group.
h. ILS Frequency
FREQUENCY PAIRS ALLOCATED FOR ILS
i. ILS Minimums
1. The lowest authorized ILS minimums, with all required ground and airborne systems components operative, are
(a) Category I Decision Height (DH) 200 feet and Runway Visual Range (RVR) 2,400 feet (with touchdown zone and centerline lighting, RVR 1800 feet).
(b) Category II DH 100 feet and RVR 1,200 feet.
(c) Category IIIa No DH or DH below 100 feet and RVR not less than 700 feet.
(d) Category IIIb No DH or DH below 50 feet and RVR less than 700 feet but not less than 150 feet.
(e) Category IIIc No DH and no RVR limitation.
NOTE: Special authorization and equipment are required for Category II and III
B. GPS OPERTION
GLOBAL POSITIONING SYSTEM (GPS) (AIM 1-1-21.)
a. System Overview
1. The GPS is a United States satellite-based radio navigational, positioning, and time transfer system operated by the Department of Defense (DoD). The system provides highly accurate position and velocity information and precise time on a continuous global basis to an unlimited number of properly equipped users. The system is unaffected by weather and provides a worldwide common grid reference system based on the earth-fixed coordinate system. For its earth model, GPS uses the World Geodetic System of 1984 (WGS-84) datum.
2. GPS provides two levels of service: Standard Positioning Service (SPS) and Precise Positioning Service (PPS). SPS provides, to all users, horizontal positioning accuracy of 100 meters, or less, with a probability of 95 percent and 300 meters with a probability of 99.99 percent. PPS is more accurate than SPS; however, this is limited to authorized U.S. and allied military, federal government, and civil users who can satisfy specific U.S. requirements.
3. GPS operation is based on the concept of ranging and triangulation from a group of satellites in space which act as precise reference points. A GPS receiver measures distance from a satellite using the travel time of a radio signal. Each satellite transmits a specific code, called a course/acquisition (CA) code, which contains information on the satellite's position, the GPS system time, and the health and accuracy of the transmitted data. Knowing the speed at which the signal traveled (approximately 186,000 miles per second) and the exact broadcast time, the distance traveled by the signal can be computed from the arrival time.
4. The GPS receiver matches each satellite's CA code with an identical copy of the code contained in the receiver's database. By shifting its copy of the satellite's code in a matching process, and by comparing this shift with its internal clock, the receiver can calculate how long it took the signal to travel from the satellite to the receiver. The distance derived from this method of computing distance is called a pseudo-range because it is not a direct measurement of distance, but a measurement based on time. Pseudo-range is subject to several error sources; for example, ionospheric and tropospheric delays, and multipath.
5. In addition to knowing the distance to a satellite, a receiver needs to know the satellite's exact position in space; this is known as its ephemeris. Each satellites signal transmits ephemeris information about its exact orbital location. The GPS receiver uses this information to precisely establish the position of the satellite.
6. Using the calculated pseudo-range and position information supplied by the satellite, the GPS receiver mathematically determines its position by triangulation. The GPS receiver needs at least four satellites to yield a three-dimensional position (latitude, longitude, and altitude) and time solution. The GPS receiver computes navigational values such as distance and bearing to a waypoint, ground speed, etc., by using the aircraft's known latitude/longitude and referencing these to a database built into the receiver.
7. The GPS constellation of 24 satellites is designed so that a minimum of five are always observable by a user anywhere on earth. The receiver uses data from a minimum of four satellites above the mask angle (the lowest angle above the horizon at which it can use a satellite).
8. The GPS receiver verifies the integrity (usability) of the signals received from the GPS constellation through receiver autonomous integrity monitoring (RAIM) to determine if a satellite is providing corrupted information. At least one satellite, in addition to those required for navigation, must be in view for the receiver to perform the RAIM function; thus, RAIM needs a minimum of 5 satellites in view, or 4 satellites and a barometric altimeter (baro-aiding) to detect an integrity anomaly. For receivers capable of doing so, RAIM needs 6 satellites in view (or 5 satellites with baro-aiding) to isolate the corrupt satellite signal and remove it from the navigation solution. Baro-aiding is a method of augmenting the GPS integrity solution by using a nonsatellite input source. GPS derived altitude should not be relied upon to determine aircraft altitude since the vertical error can be quite large. To ensure that baro-aiding is available, the current altimeter setting must be entered into the receiver as described in the operating manual.
9. RAIM messages vary somewhat between receivers; however, generally there are two types. One type indicates that there are not enough satellites available to provide RAIM integrity monitoring and another type indicates that the RAIM integrity monitor has detected a potential error that exceeds the limit for the current phase of flight. Without RAIM capability, the pilot has no assurance of the accuracy of the GPS position.
10. The Department of Defense declared initial operational capability (IOC) of the U.S. GPS on December 8, 1993. The Federal Aviation Administration (FAA) has granted approval for U.S. civil operators to use properly certified GPS equipment as a primary means of navigation in oceanic airspace and certain remote areas. Properly certified GPS equipment may be used as a supplemental means of IFR navigation for domestic enroute, terminal operations, and certain instrument approach procedures (IAPs). This approval permits the use of GPS in a manner that is consistent with current navigation requirements as well as approved air carrier operations specifications..................Sky wings
OM - - - BLUE
MM ·-·- AMBER
IM ···· WHITE
BC ·· ·· WHITE
(a) The OM normally indicates a position at which an aircraft at the appropriate altitude on the localizer course will intercept the ILS glide path.
(b) The MM indicates a position approximately 3,500 feet from the landing threshold. This is also the position where an aircraft on the glide path will be at an altitude of approximately 200 feet above the elevation of the touchdown zone.
(c) The inner marker (IM) will indicate a point at which an aircraft is at a designated decision height (DH) on the glide path between the MM and landing threshold.
3. A back course marker normally indicates the ILS back course final approach fix where approach descent is commenced.
g. Compass Locator
1. Compass locator transmitters are often situated at the MM and OM sites. The transmitters have a power of less than 25 watts, a range of at least 15 miles and operate between 190 and 535 kHz. At some locations, higher powered radio beacons, up to 400 watts, are used as OM compass locators. These generally carry Transcribed Weather Broadcast (TWEB) information.
2. Compass locators transmit two letter identification groups. The outer locator transmits the first two letters of the localizer identification group, and the middle locator transmits the last two letters of the localizer identification group.
h. ILS Frequency
FREQUENCY PAIRS ALLOCATED FOR ILS
i. ILS Minimums
1. The lowest authorized ILS minimums, with all required ground and airborne systems components operative, are
(a) Category I Decision Height (DH) 200 feet and Runway Visual Range (RVR) 2,400 feet (with touchdown zone and centerline lighting, RVR 1800 feet).
(b) Category II DH 100 feet and RVR 1,200 feet.
(c) Category IIIa No DH or DH below 100 feet and RVR not less than 700 feet.
(d) Category IIIb No DH or DH below 50 feet and RVR less than 700 feet but not less than 150 feet.
(e) Category IIIc No DH and no RVR limitation.
NOTE: Special authorization and equipment are required for Category II and III
B. GPS OPERTION
GLOBAL POSITIONING SYSTEM (GPS) (AIM 1-1-21.)
a. System Overview
1. The GPS is a United States satellite-based radio navigational, positioning, and time transfer system operated by the Department of Defense (DoD). The system provides highly accurate position and velocity information and precise time on a continuous global basis to an unlimited number of properly equipped users. The system is unaffected by weather and provides a worldwide common grid reference system based on the earth-fixed coordinate system. For its earth model, GPS uses the World Geodetic System of 1984 (WGS-84) datum.
2. GPS provides two levels of service: Standard Positioning Service (SPS) and Precise Positioning Service (PPS). SPS provides, to all users, horizontal positioning accuracy of 100 meters, or less, with a probability of 95 percent and 300 meters with a probability of 99.99 percent. PPS is more accurate than SPS; however, this is limited to authorized U.S. and allied military, federal government, and civil users who can satisfy specific U.S. requirements.
3. GPS operation is based on the concept of ranging and triangulation from a group of satellites in space which act as precise reference points. A GPS receiver measures distance from a satellite using the travel time of a radio signal. Each satellite transmits a specific code, called a course/acquisition (CA) code, which contains information on the satellite's position, the GPS system time, and the health and accuracy of the transmitted data. Knowing the speed at which the signal traveled (approximately 186,000 miles per second) and the exact broadcast time, the distance traveled by the signal can be computed from the arrival time.
4. The GPS receiver matches each satellite's CA code with an identical copy of the code contained in the receiver's database. By shifting its copy of the satellite's code in a matching process, and by comparing this shift with its internal clock, the receiver can calculate how long it took the signal to travel from the satellite to the receiver. The distance derived from this method of computing distance is called a pseudo-range because it is not a direct measurement of distance, but a measurement based on time. Pseudo-range is subject to several error sources; for example, ionospheric and tropospheric delays, and multipath.
5. In addition to knowing the distance to a satellite, a receiver needs to know the satellite's exact position in space; this is known as its ephemeris. Each satellites signal transmits ephemeris information about its exact orbital location. The GPS receiver uses this information to precisely establish the position of the satellite.
6. Using the calculated pseudo-range and position information supplied by the satellite, the GPS receiver mathematically determines its position by triangulation. The GPS receiver needs at least four satellites to yield a three-dimensional position (latitude, longitude, and altitude) and time solution. The GPS receiver computes navigational values such as distance and bearing to a waypoint, ground speed, etc., by using the aircraft's known latitude/longitude and referencing these to a database built into the receiver.
7. The GPS constellation of 24 satellites is designed so that a minimum of five are always observable by a user anywhere on earth. The receiver uses data from a minimum of four satellites above the mask angle (the lowest angle above the horizon at which it can use a satellite).
8. The GPS receiver verifies the integrity (usability) of the signals received from the GPS constellation through receiver autonomous integrity monitoring (RAIM) to determine if a satellite is providing corrupted information. At least one satellite, in addition to those required for navigation, must be in view for the receiver to perform the RAIM function; thus, RAIM needs a minimum of 5 satellites in view, or 4 satellites and a barometric altimeter (baro-aiding) to detect an integrity anomaly. For receivers capable of doing so, RAIM needs 6 satellites in view (or 5 satellites with baro-aiding) to isolate the corrupt satellite signal and remove it from the navigation solution. Baro-aiding is a method of augmenting the GPS integrity solution by using a nonsatellite input source. GPS derived altitude should not be relied upon to determine aircraft altitude since the vertical error can be quite large. To ensure that baro-aiding is available, the current altimeter setting must be entered into the receiver as described in the operating manual.
9. RAIM messages vary somewhat between receivers; however, generally there are two types. One type indicates that there are not enough satellites available to provide RAIM integrity monitoring and another type indicates that the RAIM integrity monitor has detected a potential error that exceeds the limit for the current phase of flight. Without RAIM capability, the pilot has no assurance of the accuracy of the GPS position.
10. The Department of Defense declared initial operational capability (IOC) of the U.S. GPS on December 8, 1993. The Federal Aviation Administration (FAA) has granted approval for U.S. civil operators to use properly certified GPS equipment as a primary means of navigation in oceanic airspace and certain remote areas. Properly certified GPS equipment may be used as a supplemental means of IFR navigation for domestic enroute, terminal operations, and certain instrument approach procedures (IAPs). This approval permits the use of GPS in a manner that is consistent with current navigation requirements as well as approved air carrier operations specifications..................Sky wings
