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AIM 

6/17/21 

FIG 6

3

Wind

Swell

Ditch Heading 

GOOD 

FAIR 

BEST

BEST 

DIRECTION OF 

SWELL MOVEMENT 

GOOD 

Landing parallel to the major swell 

GOOD !! 

BACK SIDE 

POOR!!! 

FACE 

Landing on the face and back of swell 

a. 

A successful aircraft ditching is dependent on 

three primary factors. In order of importance they are: 

1.  Sea conditions and wind. 

2.  Type of aircraft. 

3.  Skill and technique of pilot. 

b.  Common oceanographic terminology. 

1.  Sea. 

The condition of the surface that is the 

result of both waves and swells. 

2.  Wave 

(or Chop).  The condition of the 

surface caused by the local winds. 

3.  Swell. 

The condition of the surface which 

has been caused by a distance disturbance. 

4.  Swell Face. 

The side of the swell toward the 

observer. The backside is the side away from the 
observer. These definitions apply regardless of the 
direction of swell movement. 

5.  Primary Swell. 

The swell system having the 

greatest height from trough to crest. 

6.  Secondary Swells. 

Those swell systems of 

less height than the primary swell. 

7.  Fetch. 

The distance the waves have been 

driven by a wind blowing in a constant direction, 
without obstruction. 

8.  Swell Period. 

The time interval between the 

passage of two successive crests at the same spot in 
the water, measured in seconds. 

9.  Swell Velocity. 

The speed and direction of 

the swell with relation to a fixed reference point, 
measured in knots. There is little movement of water 
in the horizontal direction. Swells move primarily in 
a vertical motion, similar to the motion observed 
when shaking out a carpet. 

10.  Swell Direction. 

The direction 

from

 which 

a swell is moving. This direction is not necessarily the 
result of the wind present at the scene. The swell may 
be moving into or across the local wind. Swells, once 
set in motion, tend to maintain their original direction 
for as long as they continue in deep water, regardless 
of changes in wind direction. 

Distress and Urgency Procedures 

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