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motion, tend to maintain their original direction for as long as they
continue in deep water, regardless of changes

in wind direction.

11.  Swell Height.

The height between crest and trough, measured in feet. The vast
majority of ocean swells

are lower than 12 to 15 feet, and swells over 25 feet are not common at
any spot on the oceans. Successive swells

may differ considerably in height.

c.

In order to select a good heading when ditching an aircraft, a basic
evaluation of the sea is required.

Selection of a good ditching heading may well minimize damage and could
save your life. It can be extremely

dangerous to land into the wind without regard to sea conditions; the
swell system, or systems, must be taken

into consideration. Remember one axiom

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AVOID THE FACE OF A SWELL.

In ditching parallel to the swell, it makes little difference whether
touchdown is on the top of the crest

or in the trough. It is preferable, however, to land on the top or back
side of the swell, if possible. After

determining which heading (and its reciprocal) will parallel the swell,
select the heading with the most into the

wind component.

If only one swell system exists, the problem is relatively simple

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even with a high, fast system.

Unfortunately, most cases involve two or more swell systems running in
different directions. With more than one

system present, the sea presents a confused appearance. One of the most
difficult situations occurs when two

swell systems are at right angles. For example, if one system is eight
feet high, and the other three feet, plan to

land parallel to the primary system, and on the down swell of the
secondary system. If both systems are of equal

height, a compromise may be advisable

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select an intermediate heading at 45 degrees down swell to both
systems.

When landing down a secondary swell, attempt to touch down on the back
side, not on the face of the swell.

If the swell system is formidable, it is considered advisable, in
landplanes, to accept more crosswind in

order to avoid landing directly into the swell.

The secondary swell system is often from the same direction as the
wind. Here, the landing may be made

parallel to the primary system, with the wind and secondary system at
an angle. There is a choice to two directions

paralleling the primary system. One direction is downwind and down the
secondary swell, and the other is into

the wind and into the secondary swell, the choice will depend on the
velocity of the wind versus the velocity and

height of the secondary swell.

d.

The simplest method of estimating the wind direction and velocity is to
examine the windstreaks on the

water. These appear as long streaks up and down wind. Some persons may
have difficulty determining wind

direction after seeing the streaks on the water. Whitecaps fall forward
with the wind but are overrun by the waves

thus producing the illusion that the foam is sliding backward. Knowing
this, and by observing the direction of

the streaks, the wind direction is easily determined. Wind velocity can
be estimated by noting the appearance

of the whitecaps, foam and wind streaks.

The behavior of the aircraft on making contact with the water will vary
within wide limits according to

the state of the sea. If landed parallel to a single swell system, the
behavior of the aircraft may approximate that

to be expected on a smooth sea. If landed into a heavy swell or into a
confused sea, the deceleration forces may

be extremely great

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resulting in breaking up of the aircraft. Within certain limits, the
pilot is able to minimize

these forces by proper sea evaluation and selection of ditching
heading.

When on final approach the pilot should look ahead and observe the
surface of the sea. There may be

shadows and whitecaps

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signs of large seas. Shadows and whitecaps close together indicate
short and rough seas.

Touchdown in these areas is to be avoided. Select and touchdown in any
area (only about 500 feet is needed)

where the shadows and whitecaps are not so numerous.

Touchdown should be at the l

owest

 speed and rate of descent which permit safe handling and optimum

nose up attitude on impact. Once first impact has been made, there is
often little the pilot can do to control a

landplane.

e.

Once preditching preparations are completed, the pilot should turn to
the ditching heading and commence

let

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down. The aircraft should be flown low over the water, and slowed down
until ten knots or so above stall.

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Distress and Urgency Procedures