直升机教员手册 Helicopter Instructor’s Handbook
时间：2014-11-10 08:35来源：FAA 作者：直升机翻译 点击：次
|
To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. Common Student Difficulties Safety of the approach depends mainly on the thoroughness of the planning that precedes it. Students may not recognize and prepare for hard-to-see obstacles, such as power lines. Explain that supporting structures indicate the presence of lines. In a desire to make an approach directly into the wind, the student might fly over areas unsuitable for a safe landing. Advise the student that it is often preferable to make the approach with a slight crosswind, remaining downwind of potential landing areas, if possible. Should there be a need to conduct an emergency landing, turning toward the landing area would allow the approach to be conducted into the wind. Upon completion of the maneuver, discuss with the student any points that may need to be addressed. It is easier for the student to talk this through on the ground then trying to fly and listen. Before the takeoff is begun, ask the student to explain the factors being considered and the procedures being planned. This provides an opportunity to introduce factors the student may not have considered and gives the instructor a chance to evaluate the student’s judgment. Pinnacle and Ridgeline Operations Pinnacle Landings A discussion with the student on mountain weather and flying techniques, regardless of the geographical location of training, should be conducted prior to flight. Particular care must be taken to be alert to the impact of updrafts and, most importantly, downdrafts around the pinnacle. Before attempting a pinnacle landing, the student must demonstrate proficiency in precision approaches to a spot along a constant approach path. This ability is the essence of a good pinnacle landing. Have the student fly over the selected pinnacle so he or she can observe obstacles and decide on a suitable approach path, as well as determine a plan of action if the approach does not go as planned. The final approach should be started at a sufficient distance from the pinnacle to enable the student to establish an approach angle appropriate to the approach path and wind conditions. If at all possible, a normal approach angle should be used. Depth perception may be difficult because the surrounding terrain is lower and the approach angle is the only means of judging altitude. If the landing spot stays in the same angular relationship to the helicopter, the approach angle is constant. If at any time during the approach it appears to be unsafe, the approach should be abandoned according to the alternate plan. An approach that requires excessive maneuvering near the landing spot is unsatisfactory. Closure rate and approach angle should be carefully monitored during the approach because the visual cues, normally used when performing a normal approach, may not be available, and ETL must be maintained until the helicopter is nearly over the landing spot. Instructional Points If a climb is needed to reach the pinnacle or ridgeline, do it on the upwind side, when practicable, to take advantage of any updrafts. Avoid the areas where downdrafts are present, especially when excess power is limited. [Figure 11-10] The approach flightpath should be parallel to the ridgeline and into the wind as much as possible. Load, altitude, wind conditions, and terrain features determine the angle used in the final part of an approach. As a general rule, the greater the wind, the steeper the approach needs to be to avoid turbulent air and downdrafts. Groundspeed during the approach is more difficult to judge because the visual references are farther away than during approaches over trees or flat terrain. If a crosswind exists, remain clear of downdrafts on the leeward or downward side of the ridgeline. If the wind velocity makes the crosswind landing hazardous, a low coordinated turn into the wind just prior to terminating the approach might be an option. When making an approach to a pinnacle, avoid leeward turbulence and keep the helicopter within reach of a forced landing area as long as possible. It is good practice to have the student plan the approach to a 3-foot hover. Most pinnacle sites do not provide suitable landing areas. In situations where the surface is known to be flat, such as a roof top helipad, approaches can be made to the surface. Discuss with the student that actual pinnacles may not provide a cushion of IGE. Because the pinnacle surface may be uneven, rocky and sloping away in all directions, the student should anticipate the need for OGE power all the way to the surface. Upon landing, take advantage of the long axis of the area if wind conditions permit. Touchdown should be made in the forward portion of the area. Always perform a stability check prior to reducing rpm to ensure the landing gear is on firm terrain that can safely support the weight of the helicopter. Common Student Difficulties Planning As in the approach to a confined area, there are many factors to consider. The approach should be planned to fly over the most favorable areas and with an approach angle only as steep as conditions warrant. Approach Angle It may be difficult for the student to maintain a constant approach angle due to the different visual cues, as compared with a normal approach in flat terrain. The cyclic is used to control the closure rate and the collective is used to regulate the rate of descent. If the landing spot seems to be moving away, a little forward cyclic corrects it. If the landing spot seems to be moving under the helicopter, a slight rearward cyclic correction is appropriate. Airspeed Explain the importance of controlling airspeed during the final stages of the approach. An airspeed that is too low can cause a loss of ETL before the landing spot is reached, requiring an OGE hover. In some cases, the entire approach may require OGE power. An excessively high airspeed may require excessive maneuvering to avoid overflying the landing spot. The pitch attitude and airspeed control procedures become more critical on a pinnacle approach. |
推荐内容
热点内容
