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risk of “sticking” the nose in the ground. Steep bank
angles just before touchdown should also be avoided,
as they increase the stalling speed and the likelihood of
a wingtip strike.
Since the airplane’s vertical component of velocity will
be immediately reduced to zero upon ground contact, it
must be kept well under control. A flat touchdown at a
high sink rate (well in excess of 500 feet per minute
(f.p.m.)) on a hard surface can be injurious without
destroying the cockpit/cabin structure, especially during
gear up landings in low-wing airplanes. A rigid bottom
construction of these airplanes may preclude adequate
cushioning by structural deformation. Similar impact
conditions may cause structural collapse of the overhead
structure in high-wing airplanes. On soft terrain, an
excessive sink rate may cause digging in of the lower
nose structure and severe forward deceleration.
TERRAIN SELECTION
Apilot’s choice of emergency landing sites is governed
by:
• The route selected during preflight planning.
• The height above the ground when the emergency
occurs.
• Excess airspeed (excess airspeed can be converted
into distance and/or altitude).
The only time the pilot has a very limited choice is during
the low and slow portion of the takeoff. However,
even under these conditions, the ability to change the
impact heading only a few degrees may ensure a
survivable crash.
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 first selecting the desired
general area than a specific 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 obviously
better. However, as a general rule, the pilot
should not change his or her mind more than once; a
well-executed crash landing in poor terrain can be less
hazardous than an uncontrolled touchdown on an
established field.
AIRPLANE CONFIGURATION
Since flaps improve maneuverability at slow speed,
and lower the stalling speed, their use during final
approach is recommended when time and circumstances
permit. However, the associated increase in
drag and decrease in gliding distance call for caution in
the timing and the extent of their application;
premature use of flap, and dissipation of altitude,
may jeopardize an otherwise sound plan.
A hard and fast rule concerning the position of a
retractable landing gear at touchdown cannot be given.
In rugged terrain and trees, or during impacts at high
sink rate, an extended gear would definitely have a
protective effect on the cockpit/cabin area. However,
this advantage has to be weighed against the possible
side effects of a collapsing gear, such as a ruptured fuel
tank. As always, the manufacturer’s recommendations
as outlined in the AFM/POH should be followed.
When a normal touchdown is assured, and ample stopping
distance is available, a gear up landing on level, but
soft terrain, or across a plowed field, may result in less
airplane damage than a gear down landing. [Figure 16-3]
9g Deceleration
37.6 ft.
50 m.p.h. 100 m.p.h.
9.4 ft.
Figure 16-2. Stopping distance vs. groundspeed.
Figure 16-3. Intentional gear up landing.
Ch 16.qxd 5/7/04 10:30 AM Page 16-3
16-4
Deactivation of the airplane’s electrical system before
touchdown reduces the likelihood of a post-crash fire.
However, the battery master switch should not be
turned off until the pilot no longer has any need for
electrical power to operate vital airplane systems.
Positive airplane control during the final part of the
approach has priority over all other considerations,
including airplane configuration and cockpit checks.
The pilot should attempt to exploit the power available
from an irregularly running engine; however, it is generally
better to switch the engine and fuel off just
before touchdown. This not only ensures the pilot’s
initiative over the situation, but a cooled down engine
reduces the fire hazard considerably.
APPROACH
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 field.
• Obstacles in the final approach path.
　
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