Departure stalls are the most common stalls. They are also the most dangerous
as they are seldom recoverable. A Bucker-Jungmann C-104 biplane took-off and
climbed to about 200 feet in a steep nose high attitude before stalling and
crashing. The pilot and passenger received minor injuries. An amphibious
Challenger IIA was observed to be climbing over some tall trees after take-off,
when it stalled and crashed in a field. The passenger was seriously injured and
the pilot was killed. A Zenair Zodiac CH601 HD/A completed a touch and go and
was climbing out when it stalled, rolled and yawed to the right, and struck the
ground inverted in a steep nose down attitude. A fire broke out and both pilot
and passenger were fatally injured. The pilot of a Zenith CH200 was attempting
to overshoot from a poor landing when at 10 to 20 feet above the runway the left
wing dropped and struck the ground beside the runway. The aircraft cartwheeled
and came to rest upright. Neither the pilot or passenger were injured. A C-172
pilot started to abort his take-off after hearing a loud bang. When he realized
he was drifting to the left of the runway, he applied full power and attempted
to get airborne before departing the side of the runway. The aircraft stalled at
about 40 to 50 feet, the left wing dropped and the aircraft crashed in a steep
nose down attitude. The pilot received minor injuries. A C-172 rotated to a nose
high attitude just after take-off, the left wing dropped and the aircraft
impacted the ground. Three of the four on board were fatally injured. A safe
airspeed must be attained and maintained after every take-off. We don’t know why
the Bucker-Jungmann biplane pilot climbed so steeply that he stalled. It appears
the Challenger pilot was attempting to climb over some trees. This was likely
the result of poor planning. He completed a water take-off and did not allow for
the obstacle clearance climb. When it looks like we are not going to clear an
obstacle, we have a tendency to pitch the aircraft up in an attempt to get a
better climb angle. This is an illusion. Any speed above or below the best angle
of climb speed will reduce the angle of climb over the ground. The CH601, CH 200
pilots did not attain a safe airspeed after the touch and go or the overshoot.
Approaches for landing are often made with some flap and are trimmed for zero
control pressure. In the approach configuration, this is nose up trim. When full
power is applied for the touch and go or the overshoot, the aircraft will want
to pitch up and yaw to the left. If these tendencies are not controlled, the
aircraft may pitch up into a stall while yawing left. If an overshoot is
commenced at very low altitude or after the wheels have touched down, the
aircraft may get airborne in slow flight in ground effect. If the aircraft
climbs out of ground effect before a safe airspeed has been attained, the
aircraft will stall. To overshoot safely, apply full power while controlling the
pitch and yaw. Hold the aircraft in ground effect while accelerating. Raise the
flaps to the best lift flap. This is the flap setting for soft field take-offs.
We have to get rid of drag to accelerate, but we do not want to get rid of too
much lift and settle back onto the runway. Stay in ground effect until at least
the best angle of climb speed. The best rate of climb speed will allow for more
of a safety cushion. Once the best rate of climb speed has been attained, we
should climb out maintaining it. The remainder of the flaps should not be raised
until we are at a safe altitude (200 feet) and we have the best rate of climb
speed and a positive rate of climb on the VSI and the altimeter. Ground effect
is the result of the air being deflected from the wing to the runway surface
increasing the air pressure under the wing, and as a result of the ground
interfering with, and reducing, the wing tip vortices. Wing tip vortices are a
form of induced drag. An aircraft in flight near the ground therefore, has less
drag than when it is at altitude. Ground effect is effective up to a height of
about the wingspan of an aircraft (it is most effective to a height of about one
half of the wingspan of the aircraft), and so it is in play for every take-off
and landing. On take-off, ground effect will allow an aircraft to get airborne
before it reaches its stall speed. If the aircraft tries to climb out of ground
effect before it reaches a safe speed, it will stall.
The first C-172 pilot should have stayed with his decision to abort the
take-off. He would have departed the runway at low speed and would have done
little damage to the aircraft. The last C-172 accident has never been fully
explained. There has been speculation that it was loaded so that the C of G was
excessively aft. That would do it. It has also been speculated that the pilot’s
seat may have slipped back during the rotation for take-off. That could also do
it. It is a reminder to all of us that we must keep our loads within the C of G
limits specified in the Aircraft Flight Manual, and that we should make sure our
seat rails are in good repair. Departure stalls are preventable with planning,
by understanding ground effect and by anticipating the pitching and yawing
tendencies of an aircraft when full power is suddenly applied. Departure stalls
are seldom recoverable.
Dale Nielsen is an ex-Armed Forces pilot, charter pilot and air service operator. He lives in Richmond B.C. where he freelances as an aerial photography pilot and Class 1 flying instructor. Nielsen is also the author of seven flight training manuals published by Canuck West Holdings.
Got an aviation safety story to tell? Dale Nielsen would like to hear from pilots who have educational aviation experiences to relate. Excerpts from these stories will be used in upcoming safety articles. Dale can be contacted via e-mail: dnielsen@idmail.com.
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