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height of the secondary swell. [Figure 8-7]
Direction of
Swell Movement
Direction of
Swell Movement
Direction of
Swell Movement
Position of Swell Halfway
Through Runout
Position of Swell at
End of Runout
Position of Swell
at Touchdown
Figure 8-5. Landing in the same direction as the movement of the swell increases the apparent length between swell crests.
Ch 08.qxd 8/25/04 11:27 AM Page 8-4
8-5
Due to the rough sea state, landings should not be
attempted in winds greater than 25 knots except in
extreme emergencies. Crosswind limitations for each
type of seaplane must be the governing factor in crosswind
landings.
EFFECT OF CHOP
Chop consists of small waves caused by local winds in
excess of 14 knots. These small waves ride on top of
the swell system and, if severe, may hide the underlying
swell system. Alone, light and moderate chop are
not considered dangerous for landings.
NIGHT OPERATIONS
Night landings in seaplanes on open water are
extremely dangerous with a high possibility of damage
or loss of the seaplane. A night landing should only be
performed in an extreme emergency when no other
options are available. A night landing on a lighted runway
exposes the seaplane to much less risk.
Direction
of Swell
Direction
of Swell
Direction
of Swell
Position of Swell
at Touchdown
Position of Swell
at End of Runout
Position of Swell
Halfway Through
Runout
Landing
Heading
Landing
Heading
Primary
Swell Direction
Primary Swell
Direction
Secondary
Swell Direction
Figure 8-6. Landing against the swell shortens the apparent distance between crests, and could lead to trouble.
Figure 8-7. Landing heading in single and multiple swell systems.
Ch 08.qxd 8/25/04 11:27 AM Page 8-5
8-6
If operating at night, equip the seaplane with parachute
flares, smoke floats, glow sticks, or other markers.
SEA EVALUATION AT NIGHT
Before attempting a night landing, perform a sea state
evaluation as described in previous sections. If an
emergency occurs shortly after nightfall, a landing
heading can be determined by estimating the current
conditions from those conditions prevalent before
nightfall. If the pilot has no information to form an estimate
of the conditions, the information must be
obtained from other sources or determined by the pilot
from a sea state evaluation by flare illumination or
moonlight. If near a ship, sea weather conditions and a
recommended landing heading may be obtained from
the ship. However, a landing heading based on such
information is subject to error and should only be used
as a last resort. A pilot evaluation is preferred and can
be accomplished by performing the teardrop pattern
night sea evaluation as follows:
1. Set a parachute flare and adjust the altitude so
that the flare ignites at 1,700 feet. Altitude should
be as close to 2,000 feet as possible.
2. After the drop, adjust altitude to 2,000 feet and
maintain the heading for 45 seconds.
3. Turn back 220º, left or right, until the flare is
almost dead ahead. The sea becomes visible after
the first 70º of the turn is completed, allowing
approximately 90 seconds for sea evaluation. Use
standard rate turn (3º per second).
4. Immediately after passing the flare, if it is still
burning, the pilot may circle to make additional
evaluation during remaining burning time.
If both pilot and copilot are present, the pilot should fly
the seaplane and the copilot should concentrate on the
sea evaluation. If only two flares are available and sea
conditions are known or believed to be moderate, it
may be advisable to dispense with the sea evaluation
and use both flares for landing.
NIGHT EMERGENCY LANDING
A night landing should be performed only after
exhausting all other options. Be sure all occupants are
wearing life vests and secure loose items prior to
touchdown. Remove liferafts and survival equipment
from their storage containers and give them to those
occupants closest to the exits. Prior to the landing pattern,
unlatch the doors to prevent jamming that may
be caused by airframe distortion from a hard landing.
If time permits, make distress calls and activate the
emergency locator transmitter.
LANDING BY PARACHUTE FLARE
When a landing heading has been determined and all
emergency and cockpit procedures have been
accomplished, the landing approach with the use of
parachute flares is made as follows:
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