Ask the Captain: Emergency landings on water

Question: Why do airlines on domestic flights carry life vests, with all the extra weight that entails? In all the millions of flights, can you think of a single survivable event, except the so-called Miracle on the Hudson, where life vests might have helped?

— Submitted by reader Simon, Pasadena, Calif.

Answer: Airplanes often fly domestic and overwater flights in the same day. It is not uncommon for an airplane to fly several domestic flights, then fly to Bermuda or the Caribbean. Returning from the overwater flights, it then flies other domestic legs.

One of the NTSB recommendations from the accident in the Hudson was to have all airliners have life vests available for passengers due to the large number of lakes and other bodies of water over which airplanes fly. 

Q: If you lost all engine power and could only glide back to earth, would you pick an open field or an open body of water? What factors would determine your choice?          

— James DeLong, Chillicothe, Ohio

A: An off-airport landing is a very, very remote possibility. There is not a single answer to your question. The best place to land would depend on the surrounding terrain and availability of emergency services. It could be water (such as the landing in the Hudson River) or it could be jungle (as in the case of the Varig 737 some years ago).

 Making the smoothest touchdown and having room to stop would be the most important considerations. Landing an airliner off airport is not something pilots spend time considering, due to the very low probability of it occurring.

Q: How do airlines make emergency landings in water?

— Gale Carter, N.C.

A: It is very, very rare for an airliner to attempt to land in the water. I can only remember a few jets that attempted it. The landing gear remains retracted, flaps are selected to an intermediate or full extension depending on the type of airplane, and touchdown is at the lowest possible airspeed flying parallel to the waves.

Q: After the Hudson landing, there was talk that had there been enough time to follow through the whole procedure and reach the ditch mode, the plane would have been sealed to enable it to remain afloat.  Is this true? Is there a ditch mode procedure in the manual?                      

— Aaron Heskel

A: US Airways 1549 was an Airbus A320, which has a ditching switch that closes the outflow valves to reduce water inflow following a ditching. There was not time for the flight crew to complete all of the checklists before they landed in the water; the ditching switch was not pressed. During the impact with the water, there was damage to the belly causing one or more holes in the skin. Water was entering the fuselage regardless of the position of the ditching switch, so the airplane was going to sink eventually.

There are ditching procedures in every flight manual.

John Cox is a retired airline captain with US Airways and runs his own aviation safety consulting company, Safety Operating Systems.