Ditching Light
Aircraft
I’m
glad to report that in over 50 years of flying I have never had to ditch an
aircraft. I have had a few engine failures and managed successful forced
landings, both on and off airfields. I have also survived two ejections into
the sea. A ditching is a forced landing on water, so all the drills and
skills you have learned during your regular practice forced landing exercises
will apply if you are faced with putting your aircraft safely onto the water.
Being forced to ditch
your aircraft is probably the least likely emergency you will ever face, but
you will only have one opportunity to get it right. Ditchings involving UK
registered light aircraft are rare, but not unknown. The combined statistics
for UK and USA registered light aircraft ditchings reveal two very
interesting facts. First, 88% of controlled ditchings result in little or no
injury to the aircraft occupants. There is no statistically significant
difference between high wing and low wing aircraft. Second, half of those
pilots and passengers who survive the water landing die before the rescue
services get to them. It is obviously vital for anyone planning an over-water
flight to consider their survival AFTER the ditching and to
prepare and equip themselves and their aircraft for survival.
The low survival rate following a successful ditching points to the
need for private pilots to have a greater understanding of the problems of
sea survival and ways in which they can improve their chances. “Sea
Survival” is the subject of a separate article in Gremline so this
vital aspect of a successful outcome to ditching a light aircraft will only
be touched on lightly here.
The Basics
So, there you are, half way across the English Channel when your only
engine coughs and loses power. Being a sensible pilot you are cruising at the
highest altitude available to you, everyone on board is wearing clothing
suitable for the environment outside the aircraft, they are
all wearing a life jacket they know how to use and everyone has their
shoulder harness adjusted comfortably tight. If you are missing any of those
items you have already reduced the chances of survival for yourself and your
passengers. Denim jeans are probably the worst possible clothing to wear in
any survival situation. Wet wool retains half of its dry insulating
properties; wet cotton retains only 10% of its dry insulation.
Make a MAYDAY call and switch your transponder to 7700. If you manage
to restore engine power by switching tanks, selecting HOT carb air, undoing
the mis-selection that caused the failure or whatever, you can cancel the
MAYDAY and nobody will think badly of you. If you don’t manage to sort
the problem then you are faced with a ditching.
Preparing to Ditch
You should be familiar with the performance figures for your particular
aircraft. You know the best gliding speed, you have a good idea of the
surface wind velocity from your pre-flight planning and you go into your
forced landing drills without hesitation – following the same
procedures as you have done during your regular practice forced landing over
land. Your MAYDAY call should contain as much information as possible, but
your first priority is to FLY THE AIRCRAFT. Your MAYDAY call will
follow exactly the same format as you use during your periodic
‘Practice Pan’ exercises. How often do you exercise the D&D
Cell, and yourself, with a Practice Pan call? I use ‘PAT CASATNI’
as a memory aid: ‘Position And Time, Course And Speed, Altitude, Type
of Aircraft, Nature of Distress, Intentions.’
You should know how far your aircraft will glide per thousand feet,
but it will not be very far so you are unlikely to have the option to glide
to land. Looking at a few numbers gives an idea of the distance you may
cover. If you are at 3000 feet and your aircraft has a best glide speed of 70
knots while descending at 500 feet per minute then you will cover 4.6
nautical miles in still air before you get to 1000 feet above the water and
must concentrate on the landing. (Next time you are returning from a
cross-country flight why not position yourself over the airfield, close the
throttle, trim for best glide speed and note your stabilised rate of
descent?) Now calculate your gliding range per thousand feet. Not very far,
is it? A 1:10 glide ratio is not bad for the average GA single.
During a forced landing on land you select a suitable field. Over the
sea, look for a medium sized ship that is close to your present position. Big
ships take ages to stop and it is unlikely that anyone on board will be
looking out as their radar and autopilot takes them towards the horizon.
Smaller ships are more likely to be under human control and someone on board
may spot you if you ditch ahead of the ship and parallel to its track.
Trawlers are ideal targets as there is usually somebody working on
deck.
If you were cruising at a sensible altitude you now have a few
minutes to prepare for touchdown. Check that loose articles are stowed away.
A suitcase lying on the back seat could break you neck on impact. Check that
seats are firmly locked and that harnesses are tight. Passengers should
remove and stow their headsets and glasses, if worn. Have you got a hand-held
VHF set and/or a mobile phone in a sealed plastic bag stuffed into a pocket?
You are forbidden to use your mobile phone while airborne, but it could be
very handy after touchdown. Perhaps you should unlock a door, open or
jettison the canopy. Details will depend on your aircraft type. Study of the
Flight Manual or Pilot’s Operating Handbook should uncover specific
advice. If you have plenty of time you might consider resetting your
altimeter to the area QNH so as to give a more accurate indication of your
height above the sea.
By the time you get down to 2000 feet the direction of any swell will
become obvious. The swell direction and the surface wind direction may be
totally different. If there is an obvious swell running and the wind is not
above about 20 knots then you should concentrate on touching down parallel to
the swell and land along the crest or just behind the crest, NOT in front of the crest.
If the surface wind is particularly strong in comparison to your touchdown
speed then it is probably better to land into wind rather than along the
swell. It is worth remembering that the impact force on touchdown is
proportional to the square of the speed. An aircraft touching down at 50
knots in calm windless conditions will have to dissipate 4 times as much
kinetic energy as the same aircraft touching down at the same airspeed but
landing into a 25 knot headwind. This excess of energy will have to be
absorbed by the aircraft structure and those inside the aircraft.
The following table gives an indication of the appearance of the sea
in different wind speeds and the effects this will have on your direction of
touchdown decision.
