AC 90-80C

Historical

Advisory circular · Approval of Offshore Standard Approach Procedures, Airborne Radar Approaches, and Helicopter En Route Descent Areas

A newer version is currentThis is a historical version. AC 90-80C CHG 1 Ed Update is the version in force, approved March 21, 2025.
Approved
December 21, 2017
Last reviewed
September 29, 2020
Cancels
AC90-80B
Family
AC 90-80 · 5 versions
Revision
C
14 CFR parts
91, 135

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 21, 2025.

Show pages 48–59

Appendix C C-1 APPENDIX C. ADMINISTRATIVE INFORMATION C.1 References.

C.1.1 Title 14 of the Code of Federal Regulations (14 CFR):

• Part 91, §§ 91.175, 91.181, and 91.703.

• Part 135, § 135.215.

C.1.2 FAA Orders. For current FAA orders, use the following website:

https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.list/doc umentType/order.

• Order 8260.19( ), Flight Procedures and Airspace.

• Order 8260.3( ), United States Standard for Terminal Instrument Procedures (TERPS).

• Order 8260.42( ), United States Standard for Helicopter Area Navigation (RNAV).

• Order 8900.1, Flight Standards Information Management System (FSIMS).

C.1.3 Advisory Circulars (AC). For current ACs, use the following website:

https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.list.

• AC 20-165( ), Airworthiness Approval of Automatic Dependent Surveillance-Broadcast Out Systems.

• AC 90-105( ), Approval Guidance for RNP Operations and Barometric Vertical Navigation in the U.S. National Airspace System and in Oceanic and Remote Continental Airspace.

• AC 90-114( ), Automatic Dependent Surveillance-Broadcast Operations.

• AC 91-70( ), Oceanic and Remote Continental Airspace Operations.

C.1.4 Handbooks. Instrument Procedures Handbook (FAA-H-8083-16), Chapter 7, Helicopter Instrument Procedures.

C.1.5 Technical Standard Orders (TSO). For current TSOs, use the following website:

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/MainFrame?OpenFrame Set.

• TSO-C63d, Airborne Weather Radar Equipment.

• TSO-C87, Airborne Low-Range Radio Altimeter.

• TSO-C102, Airborne Radar Approach and Beacon Systems for Helicopters.

• TSO-C145a, Airborne Navigation Sensors Using the Global Positioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS).

Appendix C C-2

• TSO-C146a, Stand-Alone Airborne Navigation Equipment Using the Global Positioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS).

• TSO-C146b, Stand-Alone Airborne Navigation Equipment Using the Global Positioning System Augmented by the Satellite Based Augmentation System.

• TSO-C146c, Stand-Alone Airborne Navigation Equipment Using the Global Positioning System (GPS) Augmented by the Satellite Based Augmentation System (SBAS).

• TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment Operating on Frequency of 978 MHz.

• TSO-C166b, Extended Squitter Automatic Dependent Surveillance-Broadcast (ADS-B) and Traffic Information Service-Broadcast (TIS-B) Equipment Operating on the Radio Frequency of 1090 Megahertz (MHz).

C.1.6 RTCA, Inc. Documents. For current RTCA documents, use the following website:

https://my.rtca.org/nc__store.

• RTCA DO-172, Minimum Operational Performance Standards for Airborne Radar Approach and Beacon Systems for Helicopters.

• RTCA DO-173, Minimum Operational Performance Standards for Airborne Weather and Ground Mapping Pulsed Radars.

• RTCA DO-208, Minimum Operational Performance Standards for Airborne Supplemental Navigation Equipment Using Global Positioning System (GPS).

• RTCA DO-229, Minimum Operational Performance Standards for Global Positioning System/Satellite-Based Augmentation System Airborne Equipment.

C.1.7 International Civil Aviation Organization (ICAO) Documents. For current ICAO documents, use the following website: https://store.icao.int/index.php/.

• ICAO Annex 2, Rules of the Air.

• ICAO Annex 6, Operation of Aircraft.

• ICAO Annex 11, Air Traffic Services.

C.2 Definitions. The following definitions apply to Offshore Standard Approach Procedure (OSAP), Airborne Radar Approach (ARA), and Helicopter En Route Descent Area (HEDA) operations unless otherwise noted. Acronyms for the definitions are enclosed in parentheses ( ). The abbreviations for operations are enclosed in brackets [ ] and indicate application only to that type of operation.

C.2.1 Aeronautical Radar Beacon [ARA]. An active transponder that responds to radar interrogations.

Appendix C C-3 C.2.2 Airborne Radar. A system comprised of weather radar with a ground mapping mode which meets the requirements identified in this AC.

C.2.3 Airborne Radar Approach (ARA) [ARA]. A nonprecision instrument operation based upon the use of an ARA system as the primary operation aid in the intermediate, final, and missed operation segments. The system is comprised of weather radar with a ground mapping mode, a Global Positioning System (GPS) navigation receiver, and the cockpit displays, controls, and instrumentation necessary to provide guidance. The airborne weather radar with a ground mapping mode is referred to as “airborne radar” in the preceding chapters.

C.2.4 Clear Area [OSAP]. An area centered on the final and missed operation course that provides 0.5 nautical mile (NM) lateral obstruction clearance starting at the decision point of the Decision Point Altitude (DPA) and continuing throughout the missed operation.

C.2.5 Clear Sector [ARA]. An area overlying and centered on the final operation course. It is 4 NM wide at the Final Approach Point (FAP) and narrows linearly to a 2 NM width at 2 NM from the operation target.

C.2.6 Clear Zone [ARA]. A rectangular zone established for a missed operation to the left or right of the final operation course and clear of any obstacle.

C.2.7 Cluster Operation [ARA]. An ARA to an offshore landing site located less than 4 NM from any other platform, rig, drill ship, or other plotted obstacle.

C.2.8 Course Bearing Cursor [ARA]. An electronically generated course line shown on a radar display to assist pilots in flying a straight line surface track between the FAP and missed approach point (MAP).

C.2.9 Course Bearing Selector [ARA]. A pilot-selectable control that positions the cursor on the display.

C.2.10 Decision Point Altitude (DPA) [OSAP]. A point located on the offset final or Delta 30° operation course at 500 feet (ft) mean sea level (MSL) between the FAP and not less than 2 NM from the operation target. At the DPA, if the radar presentation forward along the operation course is clear laterally of all obstructions by at least 0.5 NM, the operation may continue when equipped with an operable radio altimeter to 200 ft above the surface.

However, if at the DPA a lateral separation of 0.5 NM from obstructions is not assured, a missed operation must be initiated.

C.2.11 Delta 30° OSAP (Δ 30°) [OSAP]. An operation flown straight-in toward the landing site using GPS for course guidance and airborne weather radar in ground mapping mode for detecting and avoiding obstructions. The “Δ” symbol represents a heading change. At

1.1 NM from the operation target a Delta 30° turn is made to the clear area located to the left or right of course. The Delta 30° course is determined by adding 30 degrees to or subtracting 30 degrees from the inbound heading. The MAP is located no closer than

0.6 NM from the operation target.

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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