A water landing is one of the most terrifying ways a plane can come down.
While expert pilots can pull it off gracefully, bringing the plane in low, slow and easy such that it barely glides along the surface, in the event of a serious engine or structural failure an emergency water landing is often a total disaster, with the crew and passengers being killed by the impact, consumed in fire, or sinking to a watery grave.
As such, airlines, pilots and aircraft designers have gone to great lengths to develop strategies for minimizing casualties in the event of a water landing.
The recent events regarding US Airways Flight 1549 and it's incredible water landing, in which no one was more than mildly injured, shows how advanced the equipment and training has become.
Originally, the only aircraft designed to land on water were sea planes, large aircraft with hulls or pontoons which permitted them to float on the water.
Many people have seen these aircraft in popular films, as they were very prevalent in the 20s, 30s and 40s before modern, paved airports were widespread.
However, these aircraft were notoriously hard to land, and much refining and development was necessary to figure out how to get them to land on water, since even the slightest change in the waves might make the aircraft unstable.
What was learned from this was then applied to training pilots to land aircraft other than sea planes safely in water, something that became very important in the Second World War.
The Second World War brought home the need to land a plane safely on water, and fighter pilots quickly learned how to ditch in the ocean without drowning.
During this time, inflatable life vests became widely distributed, something that would later be continued in the civilian airlines after the war.
It was also determined that, in order to land on water, the underside of the aircraft needed to be very firm and smooth so that it could contact lightly with the water and skip along the surface until the aircraft slowed down.
This is why aircraft conducting a water landing retract their landing gear.
The final and most key component to landing a plane on water is to ensure that the pilot has lots of training.
US Airways Flight 1549 was very fortunate in that the pilot had many years of experience and had also served in the Air Force, which goes to great lengths to train it's pilots in terms of water landings.
As such, he did not panic, and despite the fact that he had no engine power he knew to bring in the aircraft as low and slow as possible so it would skip across the surface of the water like a stone.
This prevented the aircraft from experiencing stress on the wings and fuselage such that it might break up, which would have caused it to fill with water and sink quickly.
As it was, the aircraft was mostly intact, and it was designed to float so long as it remained in one piece.