A steep approach is used primarily when there are obstacles in the approach path that are too high to allow a normal approach. A steep approach permits entry into most confined areas and is sometimes used to avoid areas of turbulence around a pinnacle. An approach angle of approximately 13° to 15° is considered a steep approach. [Figure] Caution must be exercised to avoid the parameters for settling with power (20–100 percent of available power applied, airspeed of less than 10 knots, and a rate of descent greater than 300 fpm). For additional information on vortex ring state (formerly referenced as settling-with-power), refer to Helicopter Emergencies and Hazards section.
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| Steep approach to a hover |
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Technique
On final approach, maintain track with the intended touchdown point and into the wind as much as possible at the recommended approach airspeed (position 1). When intercepting an approach angle of 13° to 15°, begin the approach by lowering the collective sufficiently to start the helicopter descending down the approach path and decelerating (position 2). Use the proper antitorque pedal for trim. Since this angle is steeper than a normal approach angle, reduce the collective more than that required for a normal approach. Continue to decelerate with slight aft cyclic and smoothly lower the collective to maintain the approach angle.
The intended touchdown point may not always be visible throughout the approach, especially when landing to a hover. Pilots must learn to cue in to other references that are parallel to the intended landing area that will help them maintain ground track and position.
Constant management of approach angle and airspeed is essential to any approach. Aft cyclic is required to decelerate sooner than a normal approach, and the rate of closure becomes apparent at a higher altitude. Maintain the approach angle and rate of descent with the collective, rate of closure with the cyclic, and trim with antitorque pedals.
The helicopter should be kept in trim just prior to loss of effective translational lift (approximately 25 knots). Below 100′ AGL, the antitorque pedals should be adjusted to align the helicopter with the intended touchdown point. Visualize the location of the tail rotor behind the helicopter and fly the landing gear to 3 feet above the intended landing point. In small confined areas, the pilot must precisely position the helicopter over the intended landing area. Therefore, the approach must stop at that point.
Loss of effective translational lift occurs higher in a steep approach (position 3), requiring an increase in the collective to prevent settling, and more forward cyclic to achieve the proper rate of closure. Once the intended landing area is reached, terminate the approach to a hover with zero groundspeed (position 4). If the approach has been executed properly, the helicopter will come to a halt at a hover altitude of 3 feet over the intended landing point with very little additional power required to hold the hover.
The pilot must aware that any wind effect is lost once the aircraft has descended below the barriers surrounding a confined area, causing the aircraft to settle more quickly. Additional power may be needed on a strong wind condition as the helicopter descends below the barriers.
Common Errors
- Failing to maintain proper rpm during the entire approach.
- Using collective improperly in maintaining the selected angle of descent.
- Failing to make antitorque pedal corrections to compensate for collective pitch changes during the approach.
- Slowing airspeed excessively in order to remain on the proper angle of descent.
- Failing to determine when effective translational lift is being lost.
- Failing to arrive at hovering altitude and attitude, and zero groundspeed almost simultaneously.
- Utilizing low rpm in transition to the hover at the end of the approach.
- Using too much aft cyclic close to the surface, which may result in the tail rotor striking the surface.
- Failure to align landing gear with direction of travel no later than beginning of loss of translational lift.