1-1 CHAPTER 1. MANDATORY AND OPTIONAL PARAGRAPHS
1.1 Purpose of This Advisory Circular (AC). This AC provides criteria and describes acceptable methods for obtaining approval to use Offshore Standard Approach Procedures (OSAP), Airborne Radar Approaches (ARA), and Helicopter En Route Descent Areas (HEDA) to descend in uncontrolled airspace to an altitude where the pilot can proceed to land using visual references to the surface. This AC provides operational approval information for operators conducting operations under Title 14 of the Code of Federal Regulations (14 CFR) parts 91, 91 subpart K (part 91K), and 135 to support issuance of operations specifications (OpSpecs) or Letters of Authorization (LOA). The contents of this document do not have the force and effect of law and are not meant to bind the public in any way, and the document is intended only to provide information to the public regarding existing requirements under the law or agency policies.
1.2 A udience. The primary audience for this AC is the helicopter proponent, Principal Operations Inspectors (POI), and the Flight Technologies and Procedures Division’s Flight Operations Group (FOG) and Flight Procedures and Airspace Group (FPAG) when establishing offshore instrument operations.
1.3 Where You Can Find This AC. You can find this AC on the Federal Aviation Administration’s (FAA) website at https://www.faa.gov/regulations_policies/advisory_cir culars a nd the Dynamic Regulatory System (DRS) at https://drs.faa.gov.
1.4 What This AC Cancels. AC 90-80B, Approval of Offshore Standard Approach Procedures, Airborne Radar Approaches, and Helicopter En Route Descent Areas, dated April 12, 1999, is canceled.
1.5 Explanation of Changes. Editorial changes to this AC reflect current language and structure of the Flight Technologies and Procedures Division’s updated organizational nomenclature. This AC retains the OSAP, ARA, and HEDA that were in AC 90-80B. It updates the approval and maintenance procedures for an operator to obtain permission to fly the operations. All references to the use of long-range navigation-C system (LORAN-C) have been removed.
1.5.1 O peration Terminology. An OSAP, ARA, and HEDA are not considered special instrument approach procedures (IAP); therefore, the appropriate term is “instrument operations.” These operations allow helicopters to make an instrument flight rule (IFR) en route descent/letdown offshore within a specified area of operation. Upon reaching visual conditions, the pilot proceeds using visual references to a landing location to execute an offshore landing on an oil rig or platform. These instrument operations are approved by the FAA for individual operators and issued through OpSpecs or LOAs. The FAA does not verify that the procedure is clear of obstructions, only that it is over water.
The pilot verifies there are no obstructions using their approved weather radar. The FAA also does not verify that positive course guidance is available, provided the proponent is using a Global Positioning System (GPS) and has procedures to verify GPS availability for the operation. No flight inspection or other validation is provided or required.
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1.5.2 R esponsibilities. Clarified the responsibilities for the POI and added guidance for the FPAG.
1.5.3 Weath er. Added new guidance for approved weather sources and weather reporting requirements for OSAP, ARA, and HEDA (see paragraph 1.9). This guidance reflects the weather requirements that have been available via OpSpecs.
1.6 A pplicability . For onshore guidance, refer to FAA Order 8260.19, Flight Procedures and Airspace, and FAA Order 8260.42( ), United States Standard for Helicopter Area Navigation (RNAV). In lieu of following the guidance in this AC without deviation, operators may elect to follow an alternative method, provided the alternative method is found to be acceptable by the FAA.
1.6.1 Man datory terms used in this AC, such as “must,” are used only in the sense of ensuring applicability of these particular methods of compliance when the acceptable means of compliance described herein are used. This AC does not change, add, or delete regulatory requirements or authorize deviations from regulatory requirements.
1.6.2 Most of the document references in this AC are the current version as designated by parentheses ( ) placed at the end of the document title. In some cases, the actual version will be indicated by a letter. Documents without ( ) or a letter after the end of the document title designates all versions apply. As a convenience, most references are hyperlinked to the source website for that document.
1.6.3 It is not the intent of this AC to imply that operators with approvals to older or expired documents must recertify to the current version. Operators with prior approvals may continue to operate under those approvals.
1.7 Airworthiness Guidance. Airworthiness guidance is provided in this AC primarily for awareness of general legacy standards by the operator community, but it is incomplete for airworthiness applicants (refer to 14 CFR parts 27 and 29).
1.8 Background.
1.8.1 C riteria . The criteria for developing offshore instrument operations are unlike that used for IAPs. Offshore instrument operation course alignment may vary from one operation to the next at the same location. The offshore instrument operation 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 ground mapping mode is used to maintain separation from obstacles. The first instrument operation approved for helicopters operating under IFR over water was the HEDA. This operation allowed helicopters to make an IFR en route descent to a radio altitude (RA) of 400 feet (ft) within a specified area of operation that is clear of obstructions. Upon reaching visual conditions, the helicopter proceeds to its destination. HEDAs permit a single instrument operation to serve multiple offshore landing sites. Helicopter ARAs evolved from HEDAs. AC 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. ARAs were intended to replace HEDAs.
1-3 However, HEDAs 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 operation obsolete. It became apparent that a new type of operation was needed that incorporated the advantages of both HEDAs and ARAs while providing an Acceptable Level of Safety (ALoS). This resulted in OSAPs, which may be automated using a unique aircraft-patented solution. For automated OSAPs, there are avionics and application requirements of an OSAP in addition to required aircraft automation equipment.
1.8.2 Testing. In January 1980, the FAA and the National Aeronautics and Space Administration (NASA) conducted a helicopter flight test program in the Gulf of America to evaluate the feasibility of using airborne weather radar in ground mapping mode as an operation system for offshore drilling platforms. In September 1984, the FAA conducted further testing in the Gulf of America. In these later tests, airborne weather radar in ground 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 cross-wind correction angle did not exceed 10 degrees on final approach course. Recommendations from reports of these tests were used to develop guidelines for the OSAP. OSAPs 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; then, AC 90-80B added the use of GPS and the Delta 30° OSAP.
1.9 Weather.
1.9.1 Approved Weather Sources. The following are approved weather sources:
1. Providers using National Weather Service (NWS) weather as their source (including contract observatories).
2. Flight Service Stations (FSS).
3. Automated Surface Observing System (ASOS).
4. Automated Weather Observing System (AWOS).
5. Supplementary Aviation Weather Reporting System (SAWRS).
6. Limited Aviation Weather Reporting Stations (LAWRS).
7. Onsite certified weather observers.
1.9.2 Weather Report Requirements for OSAP, ARA, or HEDA.
1.9.2.1 Aircraft Performance. Aircraft performance is predicated on aircraft weight, ambient temperature, wind direction, wind speed, and altimeter setting. In order to ensure aircraft takeoff and landing limitations are met and obstacles avoided, an aviation weather report must contain at least the following elements:
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• Station identifier (e.g., airport code);
• Date and time of observation (to establish relevance of the report);
• Ambient temperature at the station (e.g., airport or seaport);
• Wind direction;
• Wind speed;
• Altimeter setting at the station;
• Visibility; and
• Ceiling.
1.9.2.2 ASOS and AWOS. An ASOS or AWOS supplies an automated surface weather observation. ASOS and AWOS observations in Aviation Routine Weather Report (METAR) and Aviation Selected Special Weather Report (SPECI) formats are transmitted electronically to the NWS where they are processed (conversion to international units) and retransmitted worldwide.
The NWS requires METAR and SPECI for the generation of the Terminal Area Forecasts (TAF). The NWS commissions ASOSs and the FAA commissions AWOS sites. The AWOSs, though not approved directly by the NWS, are approved by agreement and in collaboration with the NWS. The FAA follows the NWS commissioning and installation guidelines.
1. All ASOS are automatically NWS/FAA-approved weather sources.
2. All AWOS-3s (or better) are automatically FAA/NWS-approved weather sources. AWOS systems below the AWOS-3 level are not FAA/NWS-approved weather sources, with the exception of an AWOS-2, which is approved for limited use (see item 3 below).
3. AWOS-2 is approved for limited use only. An AWOS-2 does not report ceiling information; therefore, an AWOS-2 is not an NWS/FAA-approved weather source, for use under the following circumstances:
• IFR operations that require ceiling information are prohibited at airports where AWOS-2 reports are the only official source of weather information.
• Terminal visual flight rule (VFR) operations are prohibited at airports at which an AWOS-2 is the only official source of weather information.
• An airport at which an AWOS-2 is used solely as the official source of weather information is prohibited for use as an alternate airport.
• At airports where ceiling information is required to comply with nonstandard takeoff minimums dictated by 14 CFR part 97 or OpSpecs, IFR takeoffs are prohibited if an AWOS-2 is the sole source of weather information.
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1.9.3 Minimum IFR Altitude (MIA). The offshore MIA is as directed by air traffic control (ATC).
1.9.4 Holding. Holding may be accomplished at each of the waypoints depicted in Figure 2- 4, OSAP Initial, Intermediate, Missed Approach, and Holding Segments. A standard Area Navigation (RNAV) holding pattern with 3 NM leg length, flown at 100 knots indicated airspeed (KIAS), must be executed to remain within ATC-protected airspace.
1.9.5 Automatic Dependent Surveillance-Bro adcast (ADS-B) Installation. ADS-B equipment should be installed in accordance with AC 20-165( ), Airworthiness Approval of Automatic Dependent Surveillance-Broadcast OUT Systems. The operator’s installed ADS-B Out equipment must meet the performance requirements of one of the following FAA Technical Standard Orders (TSO) or later revisions: TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment Operating on Frequency of 978 MHz; or 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).
1.9.6 Compliance. F lightcrews must comply with the procedures prescribed in the Air Traffic Offshore IFR Helicopter Operations Letter of Agreement for the given area of operations.
Note: Flightcrews should be made aware that not enabling or stopping altitude s quawk on some transponders that are certified to TSO-C166b while operating in “ADS-B Only” airspace will lead to a condition where their aircraft’s ADS-B signal will not appear on ATC displays.
1.10 AC Feedback Form. For your convenience, the AC Feedback Form is the last page of this AC. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this AC on the Feedback Form.
2-1 CHAPTER 2. OFFSHORE STANDARD APPROACH PROCEDURES
2.1 Applicability. This chapter applies to helicopter OSAP for a descent into uncontrolled airspace to proceed using visual references to offshore landing sites conducted under instrument flight rules (IFR). The operations criteria in this AC apply to airborne weather radar with ground mapping mode that has a demonstrated navigational capability acceptable to the Administrator for OSAP.
2.1.1 T ypes of OSAP. OSAP consists of two types of procedures: Delta 30° and parallel offset OSAP. For the standard OSAP operations, the Delta 30° OSAP is preferred. A parallel offset OSAP may be used when obstructions do not allow for a Delta 30° OSAP.
2.2 H elicopter Requirements.
2.2.1 R adar and Radio Altimeter. Before being authorized to conduct OSAPs, each operator who applies must have at least one helicopter equipped with airborne radar approved for OSAP use, an IFR-approved Global Positioning System (GPS) navigation receiver, and a radio altimeter.
2.2.2 Navigation Equipment Requirements. T he navigation equipment must meet the minimum requirements of Technical Standard Order (TSO)- C129, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS); TSO- C145, Airborne Navigation Sensors Using the Global Positioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS); or TSO- C146, Stand-Alone Airborne Navigation Equipment Using the Global Positioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS); with an external course deviation indicator (CDI) or horizontal situation indicator (HSI) mounted in the pilot’s primary instrument scan.
(Refer to AC 91-70( ), Oceanic and Remote Continental Airspace Operations.)
2.2.3 Reference System Requirements. The reference coordinate datum system used for all operations must be World Geodetic System 1984 (WGS 84) or North American Datum of 1983 (NAD 83).
2.2.4 Airborne Radar.
2.2.4.1 Suitable for Use as Primary Instrument Operation Aid. The airborne weather radar systems that have proved suitable for use as primary instrument operation aids are short-range pulse radars, manufactured and approved for the purpose of weather avoidance rather than navigation. Minimum system components for operations based on airborne radar only (with or without beacon capability) are as follows:
1. Meet the requirements of either TSO-C63, Airborne Weather Radar Equipment, or TSO- C102, Airborne Radar Approach and Beacon Systems for Helicopters.
2. C ontain a stabilized 120-degree/60- degree sector scanning antenna with scan rates no less than 12/minute (min) and 24/min respectively.
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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 degrees.
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.
2.2.5 Radio Altimeter.
2.2.5.1 TSO Requirement. The radio altimeter must meet the requirements of TSO-C87, Airborne Low-Rang e Radio Altimeter.
Note: A radio altimeter must be installed and operational before descent to the radio altitude (RA) minimum descent height (MDH) is authorized.
2.3 Airworthiness.
2.3.1 Equipage and Installation Requirements. Equipment required for OSAPs must 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 applicable to each requirement and be specifically approved for OSAPs by the responsible Flight Standards office. Equipment not meeting these standards requires further evaluation and approval by FAA engineering before it may be used. Installation of airborne radar, radio altimeter, and GPS equipment may constitute a major alteration to the aircraft. Each person who approves a helicopter for return to service after modification for OSAPs must comply with the provisions of 14 CFR part 43, §§ 43.5 and 43.7.
2.4 Maintenance.
2.4.1 Title 14 CFR Part 135. Part 135 operators must maintain their aircraft under part 135 requirements and their approved maintenance program. Airborne radar, radio altimeter, and GPS maintenance must be performed for this equipment installed in the aircraft.
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2.4.2 Title 14 CFR Part 91. Part 91 operators must maintain their aircraft under part 91 operating procedures. Airborne radar, radio altimeter, and GPS maintenance must be performed for this equipment installed in the aircraft. Operators under part 91 using OSAPs who do not have an approved maintenance program should establish procedures to annually inspect and test the OSAP equipment. These procedures should include methods for analyzing malfunctions and defects to determine whether established inspections and tests reasonably ensure the equipment is maintaining its accuracy. In addition to the equipment manufacturer’s recommendations and Supplemental Type Certification (STC), the following test and inspections should be included:
2.4.2.1 Vi sual Inspection. A visual inspection to determine the condition and security of the equipment mounting, electrical wiring and connectors, radome, antennas and cables, wave guide and couplings, indicator mounts, knobs, etc.
2.4.2.2 Functional Test. A functional test of the airborne radar ground mapping mode, radio altimeter, and navigation system to determine operating condition. Tests should be performed in accordance with appropriate manufacturer’s procedures.
2.4.2.3 Other Tests/Inspections (as appropriate). Other appropriate tests and inspections are used to determine whether the complete system is operating properly.
Note: The inspection and test procedures will be approved by the Flight Standards office issuing the OSAP authorization before the operator conducts any IFR OSAP in instrument meteorological conditions (IMC).
2.5 Flight Standards Office Approval. Each operator’s maintenance program must be approved by the Flight Standards office issuing the OSAP authorization before any IFR OSAPs may be conducted. A certificated air carrier submits a written request with the proposed chart through the responsible Flight Standards office Principal Operations Inspector (POI). The responsible Flight Standards office ensures that a particular radar and GPS meet minimum requirements, the flightcrew training requirements are met, and helicopter and avionics maintenance requirements are adequate. The responsible Flight Standards office may request support from the FOG representative, if required. Each operator’s maintenance or inspection program must be approved by the Flight Standards office issuing the OSAP authorization before any OSAP operations in IMC may be conducted.
2.6 Procedure Development Criteria.
2.6.1 Sample OSAP. The certificated air carrier or operator submits the operation request including the proposed chart to the principal inspector (PI) of the responsible Flight Standards office. The PI should notify the FPAG for operational coordination within their specified area of operation. For operations outside of the responsible Flight Standards office’s operational area, the FPAG should coordinate with the controlling air traffic
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Instrument operation chart examples are in Appendix B, Figure B-1, Sample Delta 30° OSAP, and Figure B-2, Sample Parallel Offset OSAP. A separate chart for each OSAP is not required.
2.6.1.1 Pro cedure Identification. The procedure is identified as either, “DELTA 30° OSAP” or “PARALLEL OFFSET OSAP.”
2.6.1.2 Procedure Construction. En route construction provides separation of aircraft 6 NM either side of course to as small as 4 NM either side of course on airways or routes. The Minimum IFR Altitude (MIA) in offshore airspace and within oceanic airspace is charted on the operation chart. Figure 2-3, En Route Criteria, shows the plan view and cross-sectional view of these criteria in the grid system in the Gulf of America. Sample OSAP charts are in Appendix B, Figures B-1 and B-2. Chart the following notes in the plan view:
1. “Special Authorization Required. WX Radar in ground mapping mode and G PS required.”
2. “Maintain MIA until departing the en route fix.”
3. “Select a maximum of 1 NM CDI sensitivity when departing the en route fix.”
2.6.2 Initial and Intermediate Segment Construction. The initial and intermediate segment construction consists of a route segment that extends from an en route fix (grid fix in the Gulf of America) to fly over the approach target with course reversals that extend to the final course. Seven-NM arcs are also constructed for optional routing to the final course.
A 7-NM fix is charted from the approach target site for optional direct routing to the final segment. These segments are flown no lower than 900 ft mean sea level (MSL) until the Final Approach Point (FAP) inbound to the approach target (see Figure 2-4, OSAP Initial, Intermediate, Missed Approach, and Holding Segments). Chart the following note in the plan view: “Clear all obstructions by at least 0.5 NM laterally by radar after FAP inbound.”
2.6.3 Final Segment Construction. The final segment construction consists of either the Delta 30° or parallel offset OSAP, which are described in paragraphs 2.15 and 2.16.
Figure 2-5, Delta 30° OSAP, and Figure 2-6, Parallel Offset OSAP, depict the Delta 30° and parallel offset OSAPs. Chart the following notes on the Delta 30° OSAP and parallel offset OSAP:
1. “Proceed Visually to the Landing Site.”
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“Maximum Ground Speed is 70 knots between FAP and MAP.”
3. “DPA (Not less than 2 NM from approach target).” The Decision Point Altitude (DPA) must not be lower than the barometric minimum descent altitude (MDA) adjusted for the Remote Altimeter Setting Source (RASS). The DPA is charted as follows: “500 MSL or no lower than barometric MDA adjusted for RASS.”
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4. “Δ 30° heading at 1.1 NM from landing site.” In addition to Figure 2-6, annotate on the chart: “0.5 NM offset.”
2.6.3.1 Minimums. Chart the following note when the radio altimeter is not available for an operation: “Altimeter source more than 5 NM but less than 75 NM, increase MDA 5 ft for each NM beyond 5 NM.” (See Appendix B, Figures B-1 and B-2.)
2.6.4 Departure and Alternate. Chart the following notes for the departure and the alternate:
1. “Avoid radar targets by 0.5 NM laterally until reaching 900′ MSL when making IFR departures.”
2. “When an offshore facility is designated as an alternate, use 800-2 instrument procedure alternate minimums or as approved by OpSpecs, or Letter of Authorization (LOA).”
2.7 Missed Approach Procedure Construction.
1. Chart the following missed approach instructions for the Delta 30° OSAP: “Climb to 900′ via the Δ 30° heading, then climbing turn to 2000′, direct to the approach target within 10 NM and hold, 3 NM legs, or as directed by ATC.”
2. Chart the following missed approach instructions for the parallel offset OSAP:
“Climb to 900′ via the offset course, then climbing turn to 2000′, direct to the approach target within 10 NM and hold, or as directed by ATC.”
2.7.1 Missed Approach Holding [Delta 30° OSAP, Parallel Offset OSAP]. Chart the following holding instructions: “Hold over the approach target on the inbound course, 3 NM legs, maintain 2000′ or as directed by ATC.”
2.8 Operational Requirements.
2.8.1 Approved Weather Observation and Reporting Requirements. Refer to FAA Order 8900.1, Volume 3, Chapter 18, Section 7, Part H Helicopter Terminal Instrument Procedures and Airport Authorizations and Limitations.
2.8.2 Offshore Environment Operation. Operators approved to conduct IFR operation in the offshore environment in accordance with parts 91, 91K, and 135 for the appropriate operational approval (e.g., LOA, management specification (MSpec), or operations specification (OpSpec)) may comply with the requirements by any one of the following methods or one with an equivalent level of safety approved by the Administrator:
1. One station: The operation coordinates must be within 10 NM of an approved w eather reporting station.
2. Two stations: The operation coordinates must be within an observed area defined by the location of two approved weather reporting stations.
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a. In the Gulf of America as defined in Figure 2-1 and excluding the Mississippi Delta bounded area in Figure 2-2:
• The observation area centerline is established by the actual bearing between the two stations; the actual distance between the two stations is not to exceed 80 NM. The centerline must continue on either side of each weather station by 10 NM.
• The lateral width of the observed area may not be greater than 40 NM on either side of the established centerline.
• The resultant maximum observation area is a rectangle 100 NM by 80 NM.
Figure 2-1. Gulf of America Expanded Weather Box Boundary
Figure 2-2. E xcluded Area for Gulf of America Expanded Weather Box Boundary Corner Latitude Longitude NW 30 25'34.82"N 89 43'53.27"W NE 30 21'42.70"N 87 52'19.31"W SW 28 50'26.73"N 89 47'41.13"W SE 28 47'17.53"N 87 56'59.98"W
b. In all other areas:
• The observation area centerline is established by the actual bearing between the two stations; the actual distance between the two stations is not to exceed 40 NM. The centerline must continue on either side of each weather station by 10 NM.
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• The lateral width of the observed area may not be greater than 40 NM on either side of the established centerline.
• The resultant maximum observation area is a rectangle 60 NM by 80 NM.
2.8.3 Parts 91 and 135 Operators—Authorized Areas of En Route Operations, Limitations, and Provisions.
1. Operators conducting IFR operations in areas authorized by OpSpec B050, Authorized Areas of En Route Operations, Limitations, and Provisions, will comply with the requirements of the OpSpec.
2. Part 91 operations within oceanic airspace are covered in LOA H104, Helicopter Offshore Instrument Operations: Offshore Standard Approach Procedure (OSAP), Airborne Radar Approach (ARA), and Helicopter En Route Descent Area (HEDA) Operations, and the applicable International Civil Aviation Organization (ICAO) Annex.
2.9 Guidelines. Procedures and guidelines of OSAP are as follows:
1. Minimum equipment lists (MEL) must be modified to account for the effect of inoperative equipment on OSAP.
2. Flightcrews are provided with current observed coordinates for landing sites. Before departure, the flightcrew enters the observed landing site coordinates into the navigation system receiver flight plan. This action designates the landing site as a “waypoint.”
3. Flightcrews should use detailed procedures to ensure clearly defined crew duties for two-pilot operations. GPS or wide area augmentation system (WAAS) is used for course guidance, and airborne radar in ground mapping mode is used for obstruction identification and avoidance.
4. All OSAPs are applicable only to helicopter operations to and from offshore platforms, rigs, or ships, and are not to be used less than 5 NM from land.
5. Throughout this operation, the airborne radar antenna sweep must not be less than 120 degrees. Less than a 120-degree antenna sweep will limit the radar operator’s ability to accurately observe and locate obstructions. Smaller sweep angles increase the possibility of premature loss of peripheral radar targets.
2.10 En Route and Intermediate.
2.10.1 Individual OSAP Accommodation. Accommodations for individual OSAPs is not required for flight from the last fix (or en route grid waypoint in the Gulf of America) on the airway or route segment to the intermediate approach fix (IF) along a Very High Frequency Omnidirectional Range Collocated Tactical Air Navigation (VORTAC) or Area Navigation (RNAV) routing. Procedures unique to an OSAP begin at the IF, which may begin over the approach target, on an arc, or at the IF if approaching “straight-in” to the IF.