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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.
• 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.
3.8.3 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.
3.9 Course Guidance.
3.9.1 Use of Radar. T he radar operator interprets radar returns on the cockpit display and vectors the helicopter clear of observed targets to the MAP. The nature of offshore operations is such that numerous permanent or transient targets may be displayed on radar. For ARA procedures, obstructions 50 ft or higher above the surface are considered obstacles. Where landing sites are less than 100 ft above the surface, all obstacles within 50 ft of the landing site’s height are charted. Those obstacles depicted within the final approach area on the ARA chart will include known height; however, those objects not shown on the chart must be considered moving obstacles of unknown height that radar provides means of lateral rather than vertical clearance on final approach. Before final approach, vertical clearance over surface obstacles is ensured by adherence to specified minimum altitudes. Missed approach obstacle avoidance is provided by an immediate climbing turn to a clear zone.
3.10 Planning.
3.10.1 ARA P ro cedure. Operational experience has shown that an ARA procedure to a single landing site is a relatively uncomplicated operation. However, operations to and from a landing site cluster increase the potential for operator error. This can be reduced by careful evaluation of the procedure during the approval process, adequate training by the operator, proper approach planning, and use of aids such as a course bearing cursor to supplement basic airborne radar.
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3.10.2 T arget Identification . Prompt and positive identification of the landing site solely by the use of ground mapping mode can be difficult when returns from moving targets confuse the pattern of the targets depicted in a cluster area. Where identification of a cluster cannot be ensured in ground mapping mode and approved air navigation facilities are unavailable to resolve target ambiguity, the approving authority should, as an option, consider whether to require installation of a radar beacon.
3.10.3 Approach Planning. To ensure obstacle-free flightpaths on final and missed approach, it is necessary to thoroughly scan and evaluate these areas before the operation is initiated.
3.10.4 Overshooting the MAP. Range errors caused by the time required for target update, possible equipment malfunctions, equipment accuracy, and crew reaction time may cause the MAP to be closer to the landing site than the desired MAP. While turning during the missed approach, airborne radar cannot be relied upon to provide lateral obstacle avoidance. Therefore, it is imperative that crews be trained to execute an immediate climbing turn toward a clear zone at the MAP. To ensure obstacle clearance, it is necessary to initiate the missed approach at the designated MAP. Otherwise, the flightpath could transgress an area that does not provide missed approach obstacle clearance.
3.10.5 Use of Course Bearing Cursor. A final approach flown by maintaining the operation target on the course bearing cursor increases the probability that the helicopter will be on the final approach course upon arrival at the designated MAP.
3.10.6 Flexibility. An offshore ARA requires procedural flexibility to provide options for the crew in planning the approach. The approach must provide a transition from an en route fix to a downwind position before beginning the final approach. This requires a provision in the approach for selection of a FAP that accounts for variations in wind conditions. On a cluster operation, where the close proximity of other targets does not permit sufficient lateral clearance for an ARA directly to the landing site, the operation can be made to a more suitable operation target located on the perimeter of the cluster and proceed visually to the landing site. Selection of an approach target depends upon existing wind conditions that in turn determine the location of the FAP, landing site selection, and missed approach clear zone. An approved ARA operation will provide an into-the-wind final descent to a cluster perimeter or to a single landing site from any direction.
3.11 Sy stem Limitations and Procedural Consideration.
3.11.1 B lind Flightpath Segments. If the FAP is not established directly downwind and the final approach course is not directly upwind, a homing approach will result. A homing approach can result in blind flightpath segments. This means that, with wind speeds as low as 0.3 of the airspeed, segments of the flightpath may not be visible to the radar operator when using a 40-degree sweep angle. When using a 120-degree sweep angle, a wind speed of 0.9 of the airspeed may cause blind flightpath segments. Homing
3-12 approaches can occur whenever the wind speed-to-airspeed ratio is greater than or equal to:
sweep anglesin = 2
3.11.1.1 No-Wind Condit ions. In a no-wind condition, a target return 1 NM to the left or right of the 0-degree azimuth mark will disappear from the radar display at the following ranges as the distance to the target decreases:
Table 3-1. No Wind Sweep Angle Range 120 degrees 0.58 NM 80 degrees 1.19 NM 60 degrees 1.73 NM 40 degrees 2.75 NM
3.11.1.1 Cross-Wind Conditions. When a wind causes a 10-degree crab, or in a 10-degree offset approach, a target 1 NM to the side of the 0-degree azimuth mark away from the crab or offset will disappear at the following ranges:
Table 3-2. Cross Wind Sweep Angle Range 120 degrees 0.84 NM 80 degrees 1.73 NM 60 degrees 2.75 NM 40 degrees 5.67 NM Note: Lateral obstacle clearance is accomplished by radar and therefore it is important that the FAP is clearly established.
3.12 Missed Approach Area.
3.12.1 Clear Zone. The clear zone in Figure 3-3 is designed to protect the missed approach. The dimensions of this figure are based on a helicopter being on track at the MAP with a ground speed of 70 knots and a climb gradient of no less than 304 ft/NM (355 ft/min).
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3.13 Flightcrew Duties.
3.13.1 D evelopment of Approach Procedures. Operators using airborne radar for offshore instrument flight should develop detailed approach procedures to ensure clearly defined flightcrew member duties for a two-pilot operation. Confusion or misunderstanding with respect to responsibility and authority during an airborne radar operation can be detrimental to safety. The following operating procedures were found both safe and usable during procedural development testing by the National Aeronautics and Space Administration (NASA) and the FAA.
3.13.2 En Route. Offshore en route navigational guidance may be based upon any approved system appropriate to the route flown. The last en route fix is also the IF and is based on en route facilities. The radar operator obtains weather information and other relevant data for the landing area, identifies the destination area operation target and landing site, determines the FAP and missed approach clear zone, and discusses the operation with the other pilot before arrival at the IF.
3.13.3 Approach. The radar operator vectors the helicopter from the IF to a position downwind from the landing site and provides all further vectors to the MAP. The pilot makes no heading changes except to those vectors specified by the radar operator. At the FAP, the crew confirms the final approach course is clear of all obstacles by at least 1 NM before a descent is made to the RA MDA. Descent on final approach may not begin until the radar operator confirms that all of the following conditions exist:
1. A ll equipment required for the approach is operating properly.
2. The final approach track does not overlay any obstacles other than the operation target, and when descending to the RA, the clear sector is clear of all obstacles.
3. The missed approach clear zone is free of obstacles.
3.14 Missed Approach and Holding.
3.14.1 Climbing Turn. A missed approach is a climbing turn into the clear zone (Figure 3-3) then a climbing turn to the Minimum IFR Altitude (MIA) direct to the IF or as directed by air traffic control (ATC). Holding is on the IF on the inbound course with 1-min legs or as directed by ATC.
3.14.2 Conditions for Missed Approach. A missed approach will be initiated immediately if:
1. A flightcrew member has not established visual contact with the approach target at the authorized minimum visibility distance as shown on the radar display;
2. During the inbound segment, if there is any malfunction of equipment required for the operation, unless the helicopter is in visual conditions and can continue to the landing site in visual conditions;
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3. The operation target is lost during any single radar scan when the helicopter is within
2.5 NM of the target; or
4. Visual reference is lost while maneuvering to the landing site.
3.14.3 L ost Communication Procedure After the Missed Approach. Execute the published missed approach and then proceed direct to the alternate at the MIA.
3.14.4 Takeoff Minimums:
1. The standard takeoff visibility for offshore landing sites is ½ sm.
2. When departing an offshore landing site, avoid all obstructions by at least 0.5 NM when below 900 ft MSL.
3.14.5 L anding Minimums . Landing minimums must be specified as a barometric MDA based on vertical obstacle clearance, or an RA specified for use by operators with an operative radio altimeter and a course bearing cursor for operations to a cluster area. The altitude that descent is authorized depends on the following conditions:
1. A ll required equipment must be operational before descent to the RA MDA.
2. Descent below the barometric MDA is not authorized if:
• Lateral clearance of 1 NM cannot be maintained;
• Required offshore heliport facilities are not operational; and/or
• A required radio altimeter is inoperative.
3.14.6 RA M DH. The RA is the lowest altitude that a descent is authorized in operations using airborne radar in ground mapping mode, an operational radio altimeter, and for cluster approaches, using a course bearing cursor. It is the highest of the following: 200 ft RA, 50 ft RA above the landing site elevation, or 100 ft RA above the highest obstruction located within a cluster if a course bearing cursor is not used. The RA MDH visibility is ¾ sm.
3.14.7 Barometric MDA. The barometric MDA is the lowest altitude that descent is authorized when 1 NM lateral obstacle clearance is not maintained, the offshore heliport facilities are not available, or the radio altimeter is not operative. The minimum barometric MDA is increased 5 ft for each NM over 5 NM from the altimeter setting source to the landing site. The maximum distance for a remote altimeter setting source from a landing site is 75 NM. The barometric MDA visibility is ½ sm.
3.14.8 Alternate Minimums and Requirements. Standard alternate minimums of 800 ft ceiling and 2 sm visibility for nonprecision procedures apply for ARAs to be used as an alternate. Requirements to establish an airport or landing site as an alternate are listed below:
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1. Approved source of weather observations and reports;
2. Two-way communications with aircraft making an operation; and
3. Any required onshore alternate requires a standard or special instrument operation other than GPS-based that is anticipated to be operational at the estimated time of arrival (ETA), unless the aircraft is equipped with approved TSO-C145( ) or TSO-C146( ) avionics and STC for instrument operations, then the onshore can have GPS-based operation.
3.15 T raining.
3.15.1 E xperience. Before conducting ARA procedures in IMC, each flightcrew member should have:
1. T en hours of flightcrew experience operating IFR (at either crew station) in the offshore route structure.
2. A minimum of ten ARAs and at least four from each crewmember position. This may be reduced by the POI for the operator based on the flightcrew experience and proficiency.
3.15.2 T raining .
3.15.2.1 All training must be a matter of record.
3.15.2.2 After completing ARA training, each flightcrew member must pass an ARA flight proficiency check. They may then be authorized to use the ARA to 100 ft above the lowest established ceiling minimums and ½ sm above the lowest established visibility minimums. Each crewmember must then fly and record ten additional ARAs before receiving authorization to conduct operations to the lowest established ceiling and visibility minimums required by the operator. The POI may reduce these requirements based on the total crew experience provided the pilot in command (PIC) meets all the conditions of this paragraph.
3.15.2.3 The flight proficiency check is an annual requirement.
3.15.2.4 Helicopter flight simulators specifically approved for ARA training by the National Simulator Program (NSP) and the POI assigned to the operator may be used for any amount of required training.
3.15.2.5 In accordance with Order 8900.1, operators requesting authority to use ARAs are required to satisfactorily train their flightcrew members under an FAA-approved training program before beginning ARA operations. Operators should submit a proposed training program to the responsible Flight Standards office, as applicable, for approval. (See Appendix A for a sample training program.)
4-1 CHAPTER 4. HELICOPTER EN ROUTE DESCENT AREAS
4.1 Applicability. This chapter applies to HEDA procedures for offshore landing sites conducted under instrument flight rules (IFR). The procedure criteria in this AC apply to airborne weather radar with ground mapping mode that has a demonstrated navigational capability acceptable to the Administrator for HEDA operations.
4.2 Helicopter Requirements.
4.2.1 R adar and Radio Altimeter. Before being authorized to conduct HEDAs, each operator who applies must have at least one helicopter equipped with airborne radar approved for ground mapping mode use (see paragraph 4.2.4 below), an IFR-approved Global Positioning System (GPS) navigation receiver, and a radio altimeter.
4.2.2 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.)
4.2.3 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).
4.2.4 Airborne Radar.
4.2.4.1 Suitable for Use as Primary Instrument Operation Aid. The airborne weather radar systems that have proved suitable for use as primary instrument approach 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/min and 24/min 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
4-2 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.
4.2.5 Radio Altimeter.
4.2.5.1 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.
4.3 Airworthiness.
4.3.1 Minimum Airworthiness Requirements. As a minimum, systems used for HEDA operations must meet the airworthiness requirements of TSO-C63 or TSO-C102. The selected equipment components must, as a minimum, meet the referenced TSO applicable to each requirement and be specifically approved for HEDAs by the responsible Flight Standards office. Equipment not meeting these standards requires further evaluation and approval by FAA engineering before it may be used.
4.3.2 Installation Requirements. Insta llation of a systems used for HEDA operations for IFR use is a major change in type design, and the provisions of 14 CFR part 21, § 21.97 and part 43, §§ 43.5 and 43.7 apply. The following are requirements for system installation:
1. System controls and data displays must be conveniently accessible and visible to radar operators at their duty stations. The system controls should be protected against inadvertent operation.
2. Electrical power for the system should be obtained from a bus that provides maximum reliability for electrical power without jeopardizing other essential or emergency loads.
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3. The systems used for HEDA operations should not be a source of objectionable electromagnetic interference and must not be adversely affected by electromagnetic interference from other helicopter equipment.
4. Any probable malfunction of the systems used for HEDA operations should not adversely affect the normal operation of other systems or equipment installed in the helicopter.
5. System performance should not be adversely affected by helicopter attitude, altitude, or main rotor revolutions per minute (rpm) normally encountered in flight operations.
4.4 Maintenance.
4.4.1 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.
4.4.2 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 HEDAs who do not have an approved maintenance program should establish procedures to annually inspect and test the HEDA 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:
4.4.2.1 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.
4.4.2.2 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.
4.4.2.3 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 HEDA authorization before the operator conducts any IFR HEDA procedure in instrument meteorological conditions (IMC).
4.5 Flight Standards Office Approval.
4.5.1 Maintenance Program. Each operator’s maintenance program must be approved by the Flight Standards office issuing the HEDA authorization before any IFR HEDA
4-4 procedures may be conducted. A certificated air carrier submits a written request with the proposed chart through the responsible Flight Standards office’s Principal Operations Inspector (POI). The responsible Flight Standards office ensures that a particular radar and GPS meet minimum requirements, that the flightcrew training requirements are met, and helicopter and avionics maintenance requirements are adequate. The responsible Flight Standards office should 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 HEDA authorization before any HEDA operations in IMC may be conducted.
4.6 Procedure Development Criteria.
4.6.1 S ample HEDA. 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 facility and Flight Standards office (if required) for the intended operational area. An instrument operation chart example is in Appendix B, F igure B-5, Sample HEDA Chart.
A separate chart for each HEDA is not required. When the operator meets all of the requirements, the responsible Flight Standards office approves the operation and issues operations specifications (OpSpecs) or a Letter of Authorization (LOA).
4.6.2 E n Route. Apply Chapter 2, paragraph 2.10 for en route criteria.
4.6.3 Intermediate Segment. The plan view of the intermediate segment and HEDAs are shown in Figure 4-1, HEDA Descent Criteria. The intermediate approach fix (IF) is the last fix prior to the HEDA. The intermediate area is the same width dimensions as the en route segment at the IF. The outside edges of the intermediate segment at the IF are drawn tangent to the HEDA. The HEDA is a circle that has a radius of 4 NM. The HEDA must be free of all obstacles and must be located over the water. The Required Obstruction Clearance (ROC) for the intermediate segment is 500 ft with a descent charted to no lower than 900 ft mean sea level (MSL) or no lower than the barometric minimum descent altitude (MDA) adjusted for the Remote Altimeter Setting Source (RASS). The HEDA operation requires special authorization and equipment. Chart the following note in the plan view of the chart: “Special Authorization Required. WX RADAR in ground mapping mode, and GPS Required.”
4.6.4 IF. The IF is established at no more than 20 NM from the HEDA coordinates.
4.6.5 Final Approach Point (FAP). The FAP is established on the HEDA circle. A descent is made at the FAP to the MDA.
Figure 4-1. HEDA Descent Criteria
NOT FOR NAVIGATION Plan View NOT TO SCALE 1 HEDA Coordinate HEDA Area (No Obstacles Within This Area) The Intermediate Fix (IF) Final Approach is Established No Farther Point (FAP) Than 20 NM from the HEDA
• Coordinates.
Required Obstacle Clearance (ROC) in the Intermediate Segment is 1 500 ft with Descents to No Lower Than 900 ft MSL 1 Intermediate
• Fix (IF)
- 6 NM En Route S MISSED APPROACH Climb to 900 in the HEDA then Climbing Turn to the 2000, Directto the HEDA Profile View coordinates. Remain within 10 NM and Hold or as directed by ATC.
HOLDING AFTER MISSED APPROACH:
Hold over HEDA coordinates on the In bound course, 3 NM legs, maintain 2000 or as directed by ATC HEDA 400 it RA or *700 it MSL * Barometric MDA Increased 5 ft for Each Mile Over 5 Miles Sea Level Saximum is are coordinates timeter Source is 75 NM 4 NM "4
4.6.6 Altitude Minimums. All required flight and navigation equipment must be installed and operative to descend to the 400 ft RA minimums. Chart the following notes (see Appendix B, Figure B-5):
1. "The MDA is 700' MSL with radio altimeter or airborne radar ground mapping mode inoperative."
2. The MDA is 700' MSL with obstruction in HEDA."
3. "Altimeter source more than 5 NM but less than 75 NM, increase MDA 5' for each NM over 5 NM from HEDA coordinates."
4. "Descent below 700' is not authorized unless HEDA is clear of all obstructions."
5. "Descent from MIA to 900' MSL is not authorized until within 20 NM of the HEDA coordinates."
4.6.7 Visibility Minimums. Chart the following note on the published operation: "Proceed VFR to the Landing Site."
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4.6.8 Missed Approach. A mi ssed approach is made when visual conditions cannot be established and maintained at the HEDA coordinates.
1. Chart the following missed approach instructions: “Climb to 900, then climbing turn to the 2000, direct to the HEDA coordinates. Remain within 10 NM and hold or as directed by ATC.”
2. Chart the following missed approach holding instructions: “Hold over the HEDA coordinates on the inbound course, 3 NM legs, maintain the 2000 or as directed by ATC.”
3. Filing a HEDA as an alternate in an IFR flight plan is not authorized. Chart the following note: “Filing HEDA as an alternate not authorized.”
4.7 Operational Requirements.
4.7.1 Approved Weather Observation and Reporting Requirements. R efer to FAA Order 8900.1, Volume 3, Chapter 18, Section 7, Part H Helicopter Terminal Instrument Procedures and Airport Authorizations and Limitations.
4.7.2 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 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 wea ther reporting station.
2. Two stations: The operation coordinates must fall within an observed area defined by the location of two approved weather reporting stations.
a. In the Gulf of America as defined in Figure 4-2, Gulf of America Expanded Weather Box Boundary, and excluding the Mississippi Delta bounded area in Figure 4-3, Excluded Area for Gulf of America Expanded Weather Box Boundary:
• 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.