Hi Capt Lim,
Your site is wonderful - thank you for the detailed information!
I have one quick question.... I am flying from Manchester to Atlanta on a Delta Airlines Boeing 777 in March - and a question just came to my mind!
Can a Boeing 777 land on water? If so, would it float?
Thank you for the interesting question. The chance of a Boeing airplane or an airliner making a water landing is extremely remote. The only occasion I can think of is an aircraft running out of fuel. This happened to a hijacked Sudanese airplane somewhere in East Africa some years back. Even if an airplane did land on the water, floatation tests conducted on the old Boeing Strata-Cruisers, KC-97 refueling tankers and the Russian TU-124s indicated that successful water landings are possible. There is quite a lot of buoyancy in the aircraft body due to the size of the fuel tanks which has air trapped in them and the sealed cargo bay when locked, is similar to that of a boat.
A Boeing 777 is designed to be capable of ditching safely on the water and stay afloat. That is why there are 8 slide rafts in the aircraft capable of accommodating more than 300 passengers in the event of a safe ditching on the sea.
How long will the B777 stay afloat on the water will depends on many factors. Firstly, there must not be substantial damage on the aircraft body to cause massive leaks. Secondly, the ditching must be properly executed (it is possible to do so) and the impact with the water surface must be reduced sufficiently to that of a normal landing profile. The sea condition must also be reasonably smooth.
According to Boeing, if the Boeing 777 ditching is properly handled with an optimum center of gravity and normal gross weight, the airplane should come to a rest slightly nose high on the water. The forward doors should be about four and a half feet and the aft doors be about two and a half feet above the water. At high gross weight, the aft doors may be less that two feet.
After ditching, an undamaged Boeing777 will stay afloat for a fairly long time - something like a drifting boat on the sea (see story below).
Hope that my answers will ease your mind as you fly from Manchester to Atlanta!
Have a safe and pleasant flight!
A Boeing 737-300 ditched successfully
On the 16th of January 2002, a Boeing 737-300 belonging to an Indonesian Airline had both its engines flamed out - a term to describe that the jet engines had failed. It happened as it commenced its descend to 9000 feet through thunderous clouds that were filled with rain.
The crew then tried to relight the engines but it failed to revive. Compared to a Boeing 777 where the relighting process is automatic, the Boeing 737 did not appear to have this advanced facility. In addition to this, on a Boeing 777, the APU will automatically light up as well when it senses both engine failures. The APU or the auxiliary power unit is a small jet engine that is located in the tail section and powers the electricity and air-conditioning of the airplane.
When the engine failed, the Captain maneuvered the airplane so that it could glide at an optimum speed of around 240 knots. This would cause the airplane to lose height rapidly at about 3000 feet per minute. He then attempted to make a forced landing, but preferred to ditch into water if only he could locate the sea. As the sea was out of reach, he decided to ditch on a river instead.
During the forced landing process, the Captain tried to decelerate from 240 to 150 knots by use of the flaps, but the hydraulics were not available to power the action. (In a Boeing 777, there is an emergency device known as a RAT or Ram Air Turbine, which is powered by free airflow as the airplane glide down with dead engines. The RAT would provide electrical power during this critical phase of the emergency.) Luckily, the ditching was very well executed and the Boeing 737 came to a stop, floating near the side of the river.
This was one of the very rare situations where a commercial airplane lost both engines and was able to ditch successfully. So Murphy Law is right! Engineers were unable to determine the exact cause of the failure yet but it was speculated that engine icing was one of the possible cause of the flame out. (In this accident, 23 people were injured in the plane carrying 54 passengers and a crew of 6. One stewardess died when she was drowned in the river.)
A Boeing 737 ditched successfully on a river