Advisory Circular SUBJECT: Approval of Offshore Standard Approach Procedures, Airborne Radar Approaches, and Helicopter En Route Descent Areas Date: 4/12/99 Initiated by: AFS-420 AC No: 90-80B Change:
1. PURPOSE. This advisory circular (AC) provides criteria and describes acceptable methods for obtaining approval to use the Offshore Standard Approach Procedure (OSAP), the Airborne Radar Approach (ARA), and the Helicopter En Route Descent Area (HEDA).
2. PRINCIPAL CHANGES. This advisory circular retains the ARA and parallel offset OSAP that were in AC 90-80A, and adds the Delta 30° OSAP and the HEDA. Global Positioning System (GPS) navigation for the OSAP and HEDA procedures has also been added.
3. CANCELLATION. Advisory Circular 90-80A, Approval of Offshore Helicopter Approaches, dated October 21, 1988, is canceled.
4. RELATED TITLE 14 OF THE CODE OF FEDERAL REGULATIONS (14 CFR).
a. 14 CFR Part 27, Airworthiness Standards: Normal Category Rotorcraft.
b. 14 CFR Part 29, Airworthiness Standards: Transport Category Rotorcraft.
c. 14 CFR Part 43, Maintenance, Preventive Maintenance, Rebuilding and Alteration.
d. 14 CFR Part 91, General Operating and Flight Rules.
e. 14 CFR Part 135, Air Taxi Operators and Commercial Operators.
5. RELATED READING MATERIAL.
a. Federal Aviation Administration (FAA) documents:
(1) FAA Order 8260.3, United States Standard for Terminal Instrument Procedures (TERPS).
(2) FAA Order 8400.10, Air Transportation Operations Inspector’s Handbook, Chapter 7.
Copies of orders in paragraphs 6a(1) and (2) may be purchased from:
Superintendent of Documents U.S. Government Printing Office P.O. Box 371954 Pittsburgh, PA 15250-7954 Phone: (202) 512-1800 FAX: (202) 512-2250 Internet: HTTP://www.access.gpo.gov/su_docs
(3) FAA Order 8260.19, Flight Procedures and Airspace.
(4) FAA Order 8260.42, Helicopter Global Positioning System (GPS) Nonprecision Approach Criteria.
(5) AC 90-94, Guidelines for Using GPS Equipment for IFR En Route and Terminal Operations and for Nonprecision Instrument Approaches in the U.S. National Airspace System.
(6) AC 20-121, Airworthiness Approval of Airborne LORAN C Navigation Systems for Use in the U.S. National Airspace System.
(7) AC 20-138, Airworthiness Approval of Global Positioning System (GPS) Navigation Equipment for Use as a VFR and IFR Supplemental Navigation System.
(8) FAA Technical Standard Order (TSO) C60, Airborne Area Navigation Equipment Using Loran C Input.
(9) TSO C63c, Airborne Weather and Ground Mapping Pulsed Radars.
(10) TSO C87, Airborne Low-Range Radio Altimeter.
(11) TSO C102, Airborne Radar Approach and Beacon Systems for Helicopters.
(12) TSO C-129, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS).
FAA orders, advisory circulars, and technical standard orders in paragraphs 6a(3) through
(12) are free and may be obtained from:
U.S. Department of Transportation TASC, Subsequent Distribution Section, SVC-121.23 Ardmore East Business Center 3341Q 75th Avenue Landover, MD 20785.
Telephone: (301) 322-4961 FAX: (301) 386-5394 (7:30 a.m. - 4:30 p.m. EST)
Page iii (and iv)
b. Other documents:
(1) RTCA Inc. , formerly Radio Technical Commission for Aeronautics (RTCA) DO-172, Minimum Operational Performance Standards for Airborne Radar Approach and Beacon Systems for Helicopters.
(2) RTCA DO-173, Minimum Operational Performance Standards for Airborne Weather and Ground Mapping Pulsed Radars.
(3) RTCA DO-208, Minimum Operational Performance Standards for Airborne Supplemental Navigation Equipment Using Global Positioning System (GPS).
All RTCA documents may be purchased from:
RTCA, Inc.
1140 Connecticut Avenue N.W., Suite 1020 Washington, D.C. 20036 ATTN: Document Sales Phone: (202) 833-9339 FAX: (202) 833-9434 Internet: HTTP://www.RTCA/org
6. COMMENTS INVITED. Comments regarding this publication should be directed to:
Federal Aviation Administration ATTN: Flight Procedure Standards Branch, AFS-420 P.O. Box 25082 Oklahoma City, OK 73125 All comments submitted may not be acknowledged; however, they will be considered in the development of future revisions to AC’s and other related technical material.
L. Nicholas Lacey Director, Flight Standards Service
CONTENTS Page No.
CHAPTER 1. BACKGROUND AND DEFINITIONS 1-1
1-1. Background ------------------------------------------------------------------------------------------1-1
1-2. Definitions--------------------------------------------------------------------------------------------1-1 CHAPTER 2. OFFSHORE STANDARD APPROACH PROCEDURES 2-1
2-1. OSAP System Component Requirements--------------------------------------------------------2-1
2-2. Airworthiness----------------------------------------------------------------------------------------2-2
2-3. Maintenance------------------------------------------------------------------------------------------2-3
2-4. Inspection and Test Procedures------------------------------------------------------------------- 2-3
2-5. Approved Weather Observation and Reporting Requirements-------------------------------2-3
2-6. Training Program and Flight Crewmember Experience--------------------------------------- 2-3
2-7. Procedure Development Criteria------------------------------------------------------------------ 2-4
2-8. Operational Applications--------------------------------------------------------------------------- 2-8 CHAPTER 3. AIRBORNE RADAR APPROACH 3-1
3-1. ARA System Component Requirements---------------------------------------------------------3-1
3-2. Airworthiness----------------------------------------------------------------------------------------3-2
3-3. Maintenance------------------------------------------------------------------------------------------3-2
3-4. Inspection and Test Procedures------------------------------------------------------------------- 3-2
3-5. Approved Weather Observation and Reporting Requirements-------------------------------3-3
3-6. Training Program and Flight Crewmember Experience--------------------------------------- 3-3
3-7. Procedure Development Criteria------------------------------------------------------------------ 3-4
3-8. Operational Applications--------------------------------------------------------------------------- 3-9 CHAPTER 4. HELICOPTER EN ROUTE DESCENT AREAS 4-1
4-1. HEDA System Component Requirements-------------------------------------------------------4-1
4-2. Airworthiness----------------------------------------------------------------------------------------4-1
4-3. Maintenance------------------------------------------------------------------------------------------4-1 4-4 Inspection and Test Procedures------------------------------------------------------------------- 4-1
4-5. Weather Reporting and Preflight Action Requirements--------------------------------------- 4-1
4-6. Training Program -----------------------------------------------------------------------------------4-1
4-7. Procedure Development Criteria------------------------------------------------------------------ 4-1
4-8. Operational Applications--------------------------------------------------------------------------- 4-3 APPENDIX 1. REQUESTS FOR APPROVAL OF OSAP, ARA, OR HEDA PROCEDURES (3 pages) --------------------------------------------------------------------- 1 APPENDIX 2. SAMPLE LETTER OF AUTHORIZATION FOR OSAP, ARA, OR HEDA (2 pages)--------------------------------------------------------------------------------- 1
Page No.
APPENDIX 3. SAMPLE OPERATIONS SPECIFICATIONS FOR OSAP, ARA, OR HEDA (2 pages)-------------------------------------------------------------------------------- 1 APPENDIX 4. SAMPLE TRAINING PROGRAM FOR OSAP, ARA, OR HEDA (4 pages) ------ 1 APPENDIX 5. SAMPLE OFFSHORE INSTRUMENT CHARTS (6 pages) -------------------------- 1
Chap 1 Page 1-1 CHAPTER 1. BACKGROUND AND DEFINITIONS
1-1. BACKGROUND.
a. The criteria for developing offshore approaches is unlike that used for Standard Instrument Approach Procedures. Offshore instrument approach course alignment may vary from one approach to the next. The approach courses depend on the direction and velocity of the wind, and the location of transient obstacles such as barges with cranes, and ships. Airborne weather radar in the mapping mode is used to maintain separation from obstacles. The first instrument procedure approved for helicopters operating under instrument flight rules (IFR) over water was the HEDA’s. This procedure allows helicopters to make an IFR en route descent to a radio altitude of 400 feet within a specified area of operation that is clear of obstructions. Upon reaching visual flight rule (VFR), the helicopter proceeds to its destination. HEDA’s permit a single instrument procedure to serve multiple offshore landing sites.
Helicopter ARA’s evolved from HEDA’s. This was the first significant effort to establish IFR approach procedures to offshore platforms. Advisory Circular 90-80, Approval of Airborne Radar Approach (ARA) Procedures for Helicopters to Offshore Platforms, dated May 18, 1981, contained an acceptable means for operators to obtain approval of ARA procedures.
b. ARA approaches were usually preferred over HEDA’s because the procedure is to a specific location. The ARA’s were intended to replace HEDA’s. However, HEDA’s were retained because they required less time for approval and served larger areas. By the time an ARA is approved, the platform may have been moved to a new location, making the procedure obsolete. It became apparent that a new type approach was needed that incorporated the advantages of both HEDA’s and ARA’s while providing an acceptable level of safety.
c. In January 1980, the FAA and the National Aeronautics and Space Administration (NASA) conducted a helicopter flight test program in the Gulf of Mexico to evaluate the feasibility of using airborne weather radar in the mapping mode as an approach system for offshore drilling platforms. In September 1984, the FAA conducted further testing in the Gulf of Mexico. In these later tests, airborne weather radar in the mapping mode was evaluated to determine if it was feasible to use radar as a primary device for detecting and avoiding obstructions. The radars that were tested were found acceptable for obstruction detection and avoidance only when the crosswind correction angle did not exceed 10° on final approach.
Recommendations from reports of these tests were used to develop guidelines for the OSAP’s. OSAP’s apply to helicopter operations to and from offshore platforms, rigs, or ships and are not to be used less than 5 nautical miles (NM) from land. Previously, the OSAP had only an offset final. This AC has added the use of global positioning system (GPS) navigation and the Delta 30° OSAP.
d. Helicopter OSAP, ARA, and HEDA procedures to offshore platforms are classified as special procedures. These special procedures are developed for individual operators and issued to the users through operations specifications (OpsSpecs) or letters of authorization (LOA).
1-2. DEFINITIONS. The following definitions apply to OSAP, ARA, and HEDA procedures unless otherwise noted. Acronyms for the definitions are enclosed in parentheses ( ). The abbreviations for procedures are enclosed in brackets [ ] and indicate application only to that type of procedure.
a. Aeronautical Radar Beacon [ARA]. An active transponder that responds to radar interrogations.
Page 1-2 Chap 1
b. Airborne Radar Approach (ARA) [ARA]. A nonprecision instrument approach procedure based upon the use of an ARA system as the primary approach aid in the intermediate, final, and missed approach segments.
c. Airborne Radar Approach Systems [ARA]. A weather radar with a mapping mode, cockpit displays, controls, and instrumentation that provide approach guidance using primary radar imaging, beacon return, and/or reflectors.
d. Approach Target [ARA, OSAP]. A stationary platform, rig, or ship used as an alignment point. For an OSAP it is the landing site. For an ARA the approach target may or may not be the landing site.
e. Airborne Radar, Global Positioning System (GPS), or Long Range Navigation C (LORAN C) Approach System [OSAP]. A system comprised of a weather radar with a mapping mode, a GPS or LORAN C navigation receiver, the cockpit displays, controls, and instrumentation necessary to provide approach guidance for an OSAP procedure. The airborne weather radar with a mapping mode will be referred to as airborne radar in the succeeding chapters.
f. Area Calibration [OSAP]. A manual mode of operation requiring pilot input to the LORAN C unit, intended to reduce the effect of propagation anomalies. Application of correction values to the LORAN C system is a function of receiver design.
g. Clear Area [OSAP]. An area centered on the final and missed approach course that provides
0.5 NM lateral obstruction clearance starting at the decision point of the decision point altitude (DPA) and continuing throughout the missed approach.
h. Clear Sector [ARA]. An area overlying and centered on the final approach 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 approach target.
i. Clear Zone [ARA]. A rectangular zone established for a missed approach to the left or right of the final approach course and clear of any obstacle.
j. Cluster Approach [ARA]. An ARA to an offshore landing site located less than 4 NM from any other platform, rig, drill ship, or other plotted obstacle.
k. 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).
l. Course Bearing Selector [ARA]. A pilot-selectable control that positions the cursor on the display.
m. Decision Point Altitude (DPA) [OSAP]. A point located on the offset final or Delta 30° approach course at 500 ft MSL between the FAP and not less than 2 NM from the approach target. At the DPA, if the radar presentation forward along the approach course is clear laterally of all obstructions by at least 0.5 NM, the approach 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 approach must be initiated.
Chap 1 Page 1-3
n. Delta 30°° OSAP (∆∆ 30°°) [OSAP]. An approach flown straight-in toward the landing site using GPS or LORAN C for course guidance and airborne weather radar in the mapping mode for detecting and avoiding obstructions. The ∆ symbol represents a heading change. At 1.1 NM from the approach 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° to or subtracting 30° from the inbound heading. The MAP is located no closer than 0.6 NM from the approach target.
o. Final Approach Point (FAP). The position downwind from the approach target where the final approach is initiated.
p. Helicopter En route Descent Area (HEDA) [HEDA]. An instrument procedure that provides an en route descent and transition from IFR to VFR conditions within a specified area of operation. A HEDA is not an instrument approach procedure, and it is not authorized as an alternate destination on an IFR flight plan.
q. HEDA Coordinates [HEDA]. A point in space that is the MAP for the HEDA.
r. Intermediate Approach Fix (IF). The IF may be a VORTAC 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 approach.
s. Minimum Descent Altitude (MDA). The MDA for OSAP, ARA, and HEDA operations is based on either a radio or barometric altimeter. The radio altitude MDA is prefixed by the radio altitude (RA) and the barometric altitude MDA is prefixed by an asterisk.
t. Missed Approach Point (MAP) [OSAP, ARA]. The MAP for an OSAP is a point no closer to the approach 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 approach target, as observed on the radar display, than the minimum authorized visibility for landing.
u. Observed Coordinates. Coordinates established by a GPS TSO C129 or LORAN C TSO-C60 (WGS-84 compatible) navigation receiver for a proposed offshore landing site or HEDA location. LORAN-C coordinates are adjusted for area calibration and are normally current for one year.
However, other periods of time may be specified in the company OpsSpecs or LOA if geographical consideration and experience indicate that a one-year currency period is not appropriate. Coordinates may also be observed with a GPS receiver equivalent to or better than TSO-C129.
v. Offset Approach [ARA]. An operating technique used when the radar operator at 1 NM from the approach target, provides vectors to position the approach target off the zero azimuth mark by no more than 25 percent of the scan angle being used.
w. Offshore Standard Approach Procedure (OSAP). A procedure designed specifically for helicopters operating at least 5 NM from land. The procedure uses LORAN C or GPS for course guidance and airborne weather radar in the mapping mode for detecting and avoiding obstructions. The OSAP provides the following:
Page 1-4 Chap 1
(1) A positive fix for the FAP.
(2) A positive method of maintaining desired track over the surface on the final and missed approach course.
(3) A definite missed approach point.
x. Parallel Offset OSAP [OSAP ]. A segment of the OSAP procedure where the final approach segment is offset 0.5 NM either left or right of centerline, depending upon the missed approach clear area.
y. 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 approach procedure is not provided between the MAP and the landing site.
z. 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 procedures. The radar operator may be the pilot-in-command or second-in-command.
aa. Radio Altimeter. An instrument that uses reflected radio signals to determine the height of the helicopter above the surface.
bb. Radio Altitude (RA). The altitude of a helicopter above the surface determined by a radio altimeter.
cc. 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.
dd. Reflector [ARA]. A passive primary radar "skin-paint" source.
ee. Single Landing Site Approach [ARA]. An ARA to an offshore landing site located 4 NM or more from any other landing site, rig, ship, or other obstacle.
Chap 2 Page 2-1 CHAPTER 2. OFFSHORE STANDARD APPROACH PROCEDURES
2-1. OSAP SYSTEM COMPONENT REQUIREMENTS. (See appendixes 2 and 3 for sample letters of authorization (LOA) and operations specifications (OpsSpecs)).
a. Before being authorized to conduct OSAP’s, each operator who applies must have at least one helicopter equipped with airborne radar approved for OSAP use, an IFR approved GPS or LORAN C navigation receiver, and a radio altimeter.
b. The GPS navigation equipment must meet the minimum requirements of TSO C129 with an external course deviation indicator (CDI) or horizontal situation indicator (HSI) mounted in the pilot’s primary instrument scan. FAA Order 8400.10, Air Transportation Operations Inspector’s Handbook/Volume 4-Aircraft Equipment and Operational Authorizations/Chapter 1. Air Navigation and Communications, provides guidance for approval of this equipment to be used as sole means for long-range navigation.
c. Airborne Radar. The radar system must meet the following minimum requirements:
(1) Meet either TSO C63 or TSO C102 requirements.
(2) Contain a stabilized 120°/60° sector scanning antenna, with scan rates no less than 12 per minute and 24 per minute respectively.
(3) Contain an adjustable, bright display.
(4) Contain an alphanumeric display for selected ranges and azimuth markers; however, alphanumeric displays of selected ranges are not required when a positive means of determining the range that has been selected is available and the radar operator is appropriately trained.
(5) Contain an indicated range error that does not exceed ± 0.2 NM for display ranges of 5 NM or less.
(6) Contain a lowest selectable range display of 2.5 NM and a range mark display of 0.5 NM increments or smaller.
(7) Contain tilt control of ±±15°.
(8) Display a test pattern.
(9) Be operable in the primary mode.
(10) Be equipped with a fault monitor or self-test function.
NOTE: An operational course bearing cursor that provides course guidance may be used to supplement navigation track accuracy.
Page 2-2 Chap 2
d. Airborne LORAN C Equipment. The LORAN C must meet the following minimum requirements:
(1) TSO C60.
(2) A suitable CDI or HSI that provides course guidance and is installed in compliance with the provisions of 14 CFR Part 29.1321.
(3) Be capable of solving simple ambiguity.
(4) Have a "navigation valid" indication that is visible to the pilot.
(5) Provide distance and bearing information to waypoints.
(6) Provide visible annunciation to alert the pilot of navigation system abnormalities and course offset operations.
(7) The reference coordinate datum system used for all approaches must be World Georeference System of 1984 (WGS-84) or North American Datum of 1983 (NAD-83).
e. Radio Altimeter. The radio altimeter will meet the requirements of TSO C87.
2-2. AIRWORTHINESS. Equipment required for OSAP’s shall be installed and maintained in a manner that meets all applicable airworthiness standards. The selected equipment components must, as a minimum, meet the referenced TSO requirement and be specifically approved for OSAP’s by the Flight Standards District Office (FSDO). Equipment not meeting these standards requires further evaluation and approval by FAA engineering before it may be used. Installation of airborne radar, radio altimeter, GPS, and LORAN C equipment may constitute a major change in type design making the provisions of 14 CFR Part 21.97 applicable. Each person who approves a helicopter for return to service after modification for OSAP operations must comply with the provisions of 14 CFR Parts 43.5 and 43.7. System installation requires the following:
a. System controls and data displays must be visible and conveniently accessible to radar operators at their duty stations. The system controls should be protected from inadvertent operation.
b. Electrical power for the system should be obtained from a bus that provides maximum reliability without jeopardizing service to other essential or emergency loads.
c. The OSAP system should not be a source of objectionable electromagnetic interference or be adversely affected by electromagnetic interference from other equipment in the helicopter.
d. Any probable malfunction of the OSAP system should not adversely affect the normal operation of other systems or equipment installed in the helicopter.
e. System performance should not be adversely affected by changes in helicopter attitude, altitude, or main rotor RPM normally encountered in flight operations.