Appendix C C-4 C.2.12 Final Approach Point (FAP) [ARA, OSAP]. The position downwind from the operation target where the final operation is initiated.
C.2.13 Helicopter En Route Descent Area (HEDA) [HEDA]. An instrument operation that provides an en route descent and transition from instrument flight rules (IFR) to visual conditions within a specified area of operation. A HEDA is not an instrument approach procedure (IAP), and it is not authorized as an alternate destination on an IFR flight plan.
C.2.14 HEDA Coordinates [HEDA]. A point in space (PinS) that is the MAP for the HEDA.
C.2.15 Intermediate Approach Fix (IF). The IF may be a Very High Frequency Omnidirectional Range Collocated Tactical Air Navigation (VORTAC) distance measuring equipment (DME) fix or a waypoint based upon an approved Area Navigation (RNAV) system. The IF connects the en route structure to the intermediate segment of the operation.
C.2.16 Minimum Descent Altitude (MDA). The MDA for OSAP, ARA, and HEDA operations is based on either a radio or barometric altimeter. The radio altitude (RA) MDA is prefixed by the RA and the barometric altitude MDA is prefixed by an asterisk.
C.2.17 Minimum Descent Height (MDH). A preselected RA used in the (AUTO) logic of the flight management system (FMS). The selected MDH is used to calculate the decent gradient required from the final approach fix (FAF) to arrive at the preselected altitude
0.25 NM prior to the MAP.
C.2.18 Minimum En Route Altitude (MEA). The lowest published altitude between radio fixes which ensures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes. The MEA prescribed for a Federal airway or segment thereof, area navigation low or high route, or other direct route applies to the entire width of the airway, segment, or route between the radio fixes defining the airway, segment, or route.
C.2.19 Minimum IFR Altitude (MIA). Minimum altitudes for IFR operations as prescribed in 14 CFR part 91. These altitudes are published on aeronautical charts and prescribed in 14 CFR part 95 for airways and routes, and in 14 CFR part 97 for Standard Instrument Approach Procedures (SIAP). If no applicable minimum altitude is prescribed in part 95 or part 97, the following MIA applies:
1. In designated mountainous areas, 2,000 ft above the highest obstacle within a horizontal distance of 4 NM from the course to be flown;
2. Other than mountainous areas, 1,000 ft above the highest obstacle within a horizontal distance of 4 NM from the course to be flown; or
3. As otherwise authorized by the Administrator or assigned by air traffic control (ATC).
Appendix C C-5 C.2.20 Missed Approach Point (MAP) [OSAP, ARA]. The MAP for an OSAP is a point no closer to the operation target than 0.6 NM for the Delta 30° or 0.7 NM for the parallel offset. The MAP for an ARA is a point no closer to the operation target, as observed on the radar display, than the minimum authorized visibility for landing.
C.2.21 Observed Coordinates. Coordinates established by a GPS TSO-C129, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS) (World Geodetic System 1984 (WGS 84) compatible) navigation receiver for a proposed offshore landing site or HEDA location.
C.2.22 Offset Approach [ARA]. An operating technique used when the radar operator at 1 NM from the operation target provides vectors to position the operation target off the zero azimuth mark by no more than 25 percent of the scan angle being used.
C.2.23 Offshore Operations. Operations that routinely have a substantial proportion of the flight conducted over sea areas to or from offshore locations. Such operations include, but are not limited to, support of offshore oil, gas and mineral exploitation, and sea-pilot transfer.
C.2.24 Offshore Standard Approach Procedures (OSAP). An operation designed specifically for helicopters operating at least 5 NM from land. The operation uses GPS for course guidance and airborne weather radar in ground mapping mode for detecting and avoiding obstructions. The OSAP provides the following:
1. A positive fix for the FAP;
2. A positive method of maintaining desired track (DTK) over the surface on the final and missed operation course; and
3. A definite missed operation point.
C.2.25 Operation Target [ARA, OSAP]. A stationary platform, rig, or ship used as an alignment point. The operation target may or may not be the landing site.
C.2.26 Parallel Offset [OSAP]. A segment of the OSAP operation where the final segment is offset 0.5 NM either left or right of centerline, depending upon the missed operation clear area.
C.2.27 Proceed Visually to the Landing Site [OSAP]. This phrase requires the pilot at or prior to the MAP to acquire and maintain visual contact with the landing site. Obstacle or terrain avoidance from the MAP to the landing site is the responsibility of the pilot. A missed operation is not provided between the MAP and the landing site.
C.2.28 Radar Operator. The pilot who operates the radar. The radar operator provides obstacle identification and vector instructions to the pilot at the controls of a helicopter to avoid obstructions during OSAP, ARA, or HEDA operations. The radar operator may be the pilot in command (PIC) or second in command (SIC).
C.2.29 Radio Altimeter. An instrument that uses reflected radio signals to determine the height of the helicopter above the surface.
Appendix C C-6 C.2.30 Radio Altitude (RA). The a ltitude of a helicopter above the surface determined by a radio altimeter.
C.2.31 Reflector [ARA]. A passive primary radar “skin-paint” source.
C.2.32 Remote Altimeter Setting Source (RASS). An altimeter setting source that is more than 5 NM but less than 75 NM from OSAP and ARA landing sites or HEDA coordinates.
C.2.33 Single Landing Site Operation [ARA]. An ARA to an offshore landing site located 4 NM or more from any other landing site, rig, ship, or other obstacle.
C.2.34 Turning Point (TP). A turning transition on an OSAP from en route flight to align with the final operation course.
C.2.35 Weather Box. An observation area whose boundary is defined by the distance between two weather stations. The centerline distance between the stations may not exceed 40 NM. The centerline may continue 10 NM on either side of each weather station. The total centerline distance may not exceed 60 NM. The lateral width of the observed area is defined as an area 40 NM on either side of the defined centerline. This results in an observed area of 60 NM by 80 NM.
C.3 Acronyms.
Acronym Meaning ABAS Aircraft-Based Augmentation System AC Advisory Circular ACO FAA Aircraft Certification Office ADS-B Automatic Dependent Surveillance-Broadcast AEG Aircraft Evaluation Group AFM Aircraft Flight Manual AHRS Attitude and Heading Reference System AIP Aeronautical Information Publications AIRAC Aeronautical Information Regulation and Control ARA Airborne Radar Approach A-RNP Advanced Required Navigation Performance ARTCC Air Route Traffic Control Center ASOS Automated Surface Observing System ATC Air Traffic Control ATCT Airport Traffic Control Tower
Appendix C C-7 Acronym Meaning ATS Air Traffic Service AWOS Automated Weather Observing System baro-VNAV Barometric Vertical Navigation CA Course to Altitude CDI Course Deviation Indicator CDU Control Display Unit CF Course to Fix CFR Code of Federal Regulations CHDO Certificate-Holding District Office CMO Certificate Management Office CPDLC Controller-Pilot Data Link Communication CTA Control Area CTA/FIR Control Area/Flight Information Region DA Decision Altitude DF Direct to Fix DME Distance Measuring Equipment DP Departure Procedure DPA Decision Point Altitude DTK Desired Track EHSI Electronic Horizontal-Situation Indicator EPU Estimate of Position Uncertainty ESV Expanded Service Volume FA Fix to an Altitude FAA Federal Aviation Administration FAF Final Approach Fix FAP Final Approach Point FAS Final Approach Segment FDE Fault Detection and Exclusion FGS Flight Guidance System
Appendix C C-8 Acronym Meaning FIR Flight Information Region FLIP U.S. Flight Information Publication FM Fix to Manual Termination FMS Flight Management System FOV Field of View FRT Fixed Radius Transition FSS Flight Service Station FTE Flight Technical Error GLS GNSS Landing System GNSS Global Navigation Satellite System GPS Global Positioning System HAA Helicopter Air Ambulance HBAT Flight Standards Handbook Bulletin for Air Transportation HEDA Helicopter En Route Descent Area HSI Horizontal Situation Indicator IAF Initial Approach Fix IAP Instrument Approach Procedure ICAO International Civil Aviation Organization IF Intermediate Approach Fix IFR Instrument Flight Rules ILS Instrument Landing System IMC Instrument Meteorological Conditions IRS Inertial Reference System IRU Inertial Reference Unit ISA International Standard Atmosphere LAWRS Limited Aviation Weather Reporting System LNAV Lateral Navigation LOA Letter of Authorization LOC Localizer
Appendix C C-9 Acronym Meaning LP Localizer Performance Without Vertical Guidance LPV Localizer Performance With Vertical Guidance LRNS Long-Range Navigation System MAP Missed Approach Point MDA Minimum Descent Altitude MDH Minimum Descent Height MEA Minimum En Route Altitude MEL Minimum Equipment List METAR MIA Minimum IFR Altitude Aviation Routine Weather Report MOPS Minimum Operational Performance Standards MSL Mean Sea Level MSpec Management Specification NANU Notice Advisory to Navstar Users NAS U.S. National Airspace System NASA National Aeronautics and Space Administration NAVAID Navigational Aid NDB Nondirectional Radio Beacon NM Nautical Miles NOTAM Notice to Airmen NSE Navigation System Error NWS National Weather Service ODP Obstacle Departure Procedure OEM Original Equipment Manufacturer OpSpec Operations Specification OSAP Offshore Standard Instrument Operation PBN Performance-Based Navigation PDE Path Definition Error PEE Position Estimation Error
Appendix C C-10 Acronym Meaning PF Pilot Flying PFD Primary Flight Display PI Principal Inspector PIC Pilot in Command PinS Point in Space PM Pilot Monitoring POH Pilot’s Operating Handbook POI Principal Operations Inspector PSE Path Steering Error RA Radio Altitude RAIM Receiver Autonomous Integrity Monitoring RASS Remote Altimeter Setting Source RF Radius to Fix RFM Rotorcraft Flight Manual RNAV Area Navigation RNP Required Navigation Performance RNP AR Required Navigation Performance Authorization Required ROC Required Obstruction Clearance rpm Revolutions per Minute SAO Special Areas of Operation SAWRS Supplementary Aviation Weather Reporting System SBAS Satellite-Based Augmentation System SIAP Standard Instrument Approach Procedure SIC Second in Command SID Standard Instrument Departure SIS S-LRNS Signal in Space Single Long-Range Navigation System SPECI Aviation Selected Special Weather Report STAR Standard Terminal Arrival
Appendix C C-11 Acronym Meaning STC Supplemental Type Certificate SUPPS Regional Supplementary Procedures TAF Terminal Area Forecast TC Type Certificate TF Track to Fix TOGA Takeoff/Go-Around TP Turning Point TSE Total System Error TSO Technical Standard Order VA Heading to Altitude VFR Visual Flight Rules VHF Very High Frequency VI Heading to Intercept VM Heading to Manual VNAV Vertical Navigation VOR Very High Frequency Omni-Directional Range VORTAC Very High Frequency Omnidirectional Range Collocated Tactical Air Navigation WAAS Wide Area Augmentation System WGS World Geodetic System XTK Cross-Track
Advisory Circular Feedback Form If you find an error in this AC, have recommendations for improving it, or have suggestions for new items/subjects to be added, you may let us know by contacting the Performance-Based Flight Systems Branch (AFS-470) at 9-AWA-AFS400-Coord@faa.gov or the Flight Standards Directives Management Officer at 9-AWA-AFS-140-Directives@faa.gov.
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