landing a
seaplane
In comparison, the land surfaces of
all airports are of
firm, static matter, whereas the surface of water is changing
continually as a fluid. Floating obstacles and various
activities frequently present on the water surface may
present serious hazards during seaplane landings, especially
to the careless pilot. For these reasons, it is advisable
to circle the area of intended landing and examine it
thoroughly for obstructions such as buoys or floating
debris, and to note the direction of movement of any boats
which may be operating at the intended landing site.
Most established seaplane bases are equipped with a
windsock to indicate wind direction, but if one is not available
the wind can still be determined prior to landing. The
following are but a few of the methods by which to determine
the wind direction.
If there are no strong tides or water currents, boats
lying at anchor will weathervane and automatically point
into the wind. It is also true that sea gulls and other water
fowl usually land facing the wind. Smoke, flags, and the
set of sails on sailboats also provide the pilot with a fair
approximation of the wind direction. If there is an appreciable
wind velocity, streaks parallel to the wind are
formed on the water. During strong winds, these streaks
form distinct white lines. However, wind direction cannot
always be determined from the streaks alone. If there are
white caps or foam on top of the waves, the foam appears
to move into the wind. This illusion is caused by the waves
moving under the foam.
In seaplanes equipped with retractable landing gear
(amphibians), it is extremely important to make certain
that the wheels are in the retracted position when landing
on water. Wherever possible, a visual check of the wheels
themselves is recommended, in addition to checking the
landing gear position indicating devices. A wheels-down
landing on water is almost certain to capsize the seaplane,
and is far more serious than landing the seaplane wheels-up
on land.
The water rudder should also be in the
retracted position during landings.
The landing approach procedure in a seaplane is very
similar to that of a landplane and is governed to a large
extent by pilot preference, wind, and water conditions.
Under normal conditions a seaplane can be landed
either power-off or power-on; however, power-on landings
are recommended in most cases because this technique
gives the pilot more positive control of the seaplane
and provides a means for correcting errors in judgment
during the approach and landing. So that the slowest possible
airspeed can be maintained, the power-on landing
should be accomplished with maximum flaps extended.
The seaplane should be trimmed to the manufacturer's recommended
approach speed, and the approach made similar
to that of a landplane..
Figure 9: Touchdown attitude
Touchdown on the water should be made
in a pitch
attitude that is correct for taxiing "on the step," or perhaps
a slightly higher attitude (see Figure 9). This attitude will
result in the floats or hull first contacting the water at a
point aft of the step. Once water contact is made, the throttle
should be closed and back elevator pressure gradually
applied. The application of back pressure reduces the tendency
for the seaplane to nose down and the bows to dig in
due to increased drag of the floats as they contact the
water. The faster the speed at which a seaplane is landed,
the more water drag is encountered, resulting in a greater
nose-down attitude after touchdown. If the seaplane has a
tendency to nose down excessively with full flaps
extended, it is recommended that subsequent approaches
and landing be made with less flaps. Remember, the objective
is to land the seaplane at the slowest possible speed in
a slightly nose-up attitude
After contacting the water, gradually increase back
elevator pressure. It may be desirable at times to remain on
the step after touchdown. To do so, merely add sufficient
power and maintain the planing attitude immediately after
touchdown.
Flat, calm, glassy water is perhaps the most deceptive
condition that a seaplane pilot will experience.
The calmness
of the water has a psychological effect in that it tends
to overly relax the pilot when there should be special alertness.
Consequently, this surface condition is frequently the
most dangerous for seaplane operation.
From above, the mirror-like appearance of smooth
water looks most inviting and easy to land on but as many
pilots have suddenly learned, adequate depth perception
may be lacking. Even experienced pilots misjudge height
above the water, making timely round-outs difficult. This
results in either flying bow first into the water or stalling
the seaplane at too great a height above the water. When
the water is crystal clear and glassy, pilots often attempt to
judge height by using the bottom of the lake as a reference,
rather than the water surface.
An accurately set altimeter may be used as an aid in
determining height above the glassy water. However, a
more effective means is to make the approach and landing
near the shoreline so it can be used as a reference for judging
height above the water. Another method is to cross the
shoreline on final approach at the lowest possible safe altitude
so that a height reference is maintained to within a
few feet of the water surface.
Glassy water landings should always be made power-on,
and the need for this type of landing should be recognized
in ample time to set up the proper final approach.
During the final approach the seaplane should be flown
at the best nose-high attitude, using flaps as required or as
recommended by the manufacturer. A power setting and
pitch attitude should be established that will result in a rate
of descent not to exceed 150 feet per minute and at an airspeed
approximately 10 knots above stall speed. With a
constant power setting and a constant pitch attitude, the
airspeed will stabilize, and remain so if no changes are
made. The power or pitch should be changed only if the
airspeed or rate of descent deviates from that which is
desired. Throughout the approach the seaplane performance
should be closely monitored by cross-checking the
instruments until contact is made with the water.
Upon touchdown, back elevator control pressure
should be applied as necessary to maintain the same pitch
attitude.
Throttle should be reduced or closed only after
the pilot is sure that the aircraft is firmly on the water. Several
indications should be used.
1.A slight deceleration force will be felt. 2.A slight
downward pitching moment will be seen. 3.The sounds of
water spray striking the floats, hull, or other parts of the
aircraft will be heard.
All three cues should be used because accidents have
resulted from cutting the power rapidly after initially
touching the water. To the pilot's surprise a skip had taken
place and it was found that when the power was cut, the
aircraft was 10 to 15 feet in the air and not on the water,
resulting in a stall and substantial damage.
Maintaining a nose-up, wings-level attitude, at the correct
speed and a small rate of descent, are imperative for a
successful glassy water landing. All aspects of this
approach and landing should be considered prior to its
execution. Bear in mind that this type of approach and
landing will usually consume considerable landing distance.
Landing near unfamiliar shorelines increases the
possibility of encountering submerged objects and debris.
It is impractical to describe an ideal rough water procedure
because of the varying conditions of the surface. In
most instances, though, the approach is made the same as
for any other water landing. It may be better however, to
level off just above the water surface and increase the
power sufficiently to maintain a rather flat attitude until
conditions appear more acceptable, and then reduce the
power to touchdown. If severe bounces occur, power
should be increased and a search made for a more ideal
landing spot.
Generally, it is recommended that night water landing
in seaplanes be avoided, since they can be extremely dangerous
due to the difficulty or almost impossibility of seeing
objects in the water. If it becomes necessary to land at
night in a seaplane, serious consideration should be given
to landing at a lighted airport.
An emergency landing can
be made on land in seaplanes with little or no damage to
the floats or hull. Touchdown should be made with the
keel of the floats or hull as nearly parallel to the surface as
possible. After touchdown, full back elevator most be
applied and additional power applied to lessen the rapid
deceleration and nose-over tendency. Don't worry about
getting stopped with additional power applied after touchdown.
It will stop! The power is applied only for increasing
elevator effectiveness.
|