CHAPTER 13. Abnormal and Emergency Procedures

Terrain Selection

A pilotís choice of emergency landing sites is governed by the:

  • Route selected during prefl ight planning and
  • Height above the ground when the emergency occurs.

The only time the pilot has a very limited choice is during low and slow fl ying or during takeoff if the landing approach is always within gliding distance of the runway.

It should be understood that the amount of area for available landing sites increases at a rapid rate with increased altitude. [Figure 13-4] As an example, a WSC aircraft with a 5 to 1 glide ratio fl ying at 500 feet AGL has 500 feet multiplied by fi ve feet horizontal (or 2,500 feet) radius on the ground to select a suitable landing area. For example, use a Ĺ mile radius. The area of available landing spots is p x r2, approximately 0.8 square miles. At 1,000 feet AGL, this area would be 3.1 square miles; at 2,000 feet AGL, this is about 12.5 square miles; and at 5,000 AGL, this is almost 80 square miles.

Additionally, fl ying in a downwind direction provides more area to be covered while fl ying upwind reduces the amount of area that can be covered while looking for a suitable landing area.

If beyond gliding distance of a suitable open area, the pilot should judge the available terrain for its energy absorbing capability. If the emergency starts at a considerable height above the ground, the pilot should be more concerned about fi rst selecting the desired general area than a specifi c spot. Terrain appearances from altitude can be very misleading and considerable altitude may be lost before the best spot can be pinpointed. For this reason, the pilot should not hesitate to discard the original plan for one that is clearly better. However, as a general rule, the pilot should not change his or her mind more than once.


When the pilot has time to maneuver, the planning of the approach should be governed by three factors:

  • Wind direction and velocity
  • Dimensions and slope of the chosen fi eld
  • Obstacles in the fi nal approach path and the fi eld itself

These three factors are seldom compatible. When compromises must be made, the pilot should aim for a wind/obstacle/terrain combination that permits a fi nal approach with some margin for error in judgment or technique. A pilot who overestimates the gliding range may be tempted to stretch the glide across obstacles in the approach path. For this reason, it is sometimes better to plan the approach over an unobstructed area regardless of wind direction. Experience shows that a collision with obstacles at the end of a ground roll, or slide, is much less hazardous than striking an obstacle at fl ying speed before the touchdown point is reached.

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