Paul a grab bag is a nice idea in theory but in practice it is going to be waste of time. Where are you going to keep it for easy access as your plane starts sinking? Your time to grab it and evacuate is extremely limited; seconds rather than minutes. Strapped to the seat next to you is the only useful place. Your priority is for you and your occupants to evacuate ASAP.
Sandy sorry but your survival times are over optimistic and sea temperatures not entirely correct. Based on a major review of post accident sea survival I was heavily involved in many years ago following major loss of life in a helicopter accident in the North Sea.
http://www.caa.co.uk/docs/33/CAP641.PDF I can advise the following. (I also used to lecture on the subject.)
Summer sea temperature is
constant day and night at 6 – 8 deg C for the North Sea and English Channel in spring. It warms up during summer to reach its peak around mid autumn 12 to 14 deg C. It cools down rapidly in spring due to arctic ice melt.
Survival time in 6 deg C water is 20 minutes. Hypothermia takes over, you go unconscious and drown. In 12 deg C water you are looking at maybe an hour. In 6 deg C water a well insulated and properly sealed survival suit will in theory give you 4 hours in reality 2.5 to 3 hours.
This is because you degrade the insulation with your own body fluids. Sweat and urine, add to that any leaks around the seals and zips letting in sea water.
Your only useful strategy is to wear a well-insulated survival suit, with constant wear life jacket that has self-righting buoyancy characteristics. Without self-righting if you go unconscious the waves will roll you over a leave you face down in the water – you drown. With self-righting buoyancy characteristics you are always kept face up.
Also needs a crotch strap to anchor the thing to your shoulders. If not when in the water you slide down the thing until suspended from your arm pits by the waist strap. Your head is now under water, you drown.
Another also need is a water splash, face mask hood. Waves splash water on to your face. When conscious you physically react to keep the water out of your mouth and airways. As you start to go unconscious you can no longer do that so you drown.
As for useful gadgets wear them on your suit and or life jacket.
That is the ONLY way you know you will get them out of the aircraft. A knife to cut you free. A PLB. A whistle, and a long endurance locater light / strobe and reflective tape on the above water sections of your life jacket and spray hood. Flares if you think you need them. Insulated gloves are also a must. In 6 deg C water your hands rapidly go stiff and numb and you cannot operate any of the fiddley controls on your gadgets.
Carrying a life raft is always useful. And being inside it significantly increase survival time. Body heat loss in air is about 20 times slower than in cold water. But consider the following. Where are you going to keep it on the aircraft so that it is readily available? Even when packed its buoyant, so if its in a partially flooded aircraft how you going to get it out if its floating above a door or hatch opening? OK so you get it out and inflate it. Its evens that it will be floating upsde down so you have to right it. Have you been practically trained to do that? Its not easy in fact can be downright dangerous - entrapment underneath it, flailing gas cylinders and all that.
Also before you inflate it you need to tie it off to something like your sinking aircraft. Else it will get blown way by the wind – the canopy makes a nice sail. 20 kt wind, you swimming after at 2 kts, separation speed 18 kts in favour of the raft.
In terms of ditching in the channel the middle bit is the best. Right in the middle of the sea lanes. Plenty of chances of being picked up by passing ship. Worst places are close to the coast, away from shipping lanes. That is where most post ditching “survivors” die. Takes too long to get SAR assets to find and rescue you in good time. A very high percentage of occupants survive the on water arrival yet only half live to tell the tale. The rest die from hypothermia induced drowning. Aggravated by not wearing proper protective kit and not having any location aids.
Finally invest in an underwater escape and survival training course. Can totally recommend it. Worth their weight in gold. Half day courses are available.
