Soft landing

The safe landing of US Airways Flight 1549, shown here as the plane is hoisted from the frigid Hudson River, was aided by luck, training and engineering. Image credit: Associated Press
Date:30 April 2009 Tags:,

Surviving the watery crash of an airliner with no engines was no miracle.

No airliner that suffers total engine failure after hitting a flock of geese can be called “lucky”. The odds of striking birds large enough to destroy two aircraft engines are extremely remote. Yet, when birds knocked out both engines of US Airways Flight 1549 after it took off from LaGuardia Airport on January 15, a series of fortunate events followed that enabled the Airbus A-320 to ditch into the Hudson River with no loss of life. Many called it a miracle; PM believes it was a combination of good vehicle design, smart piloting and, yes, just plain luck.

1 Aircraft are made to survive total engine loss. How can computer-controlled planes steer without power? Auxiliary power units and ram-air turbines that drop from the fuselage can power the hydraulics that control an aircraft. Damaged engines can provide a trickle of power from the wind-milling of their blades as they move through the air.

2 Air emergencies are more survivable at higher altitudes. Flight recorders show that the aircraft reached a maximum altitude of 975 m. If the bird strike had happened lower, just after take-off, the plane probably would have plunged into the rough and frigid waters of Long Island Sound at a very high speed, in a spot where rescue would have taken longer.

3 Rivers can make decent runways. Captain Chesley Sullenberger determined that he did not have enough control to return to LaGuardia. Without the engines working in reverse to slow the plane, he might have overshot the runway. If you have to put a jet down, the Hudson River is a close-to-ideal venue. It’s wide, the water is relatively calm and rescuers are close at hand.

4 Ditched aircraft don’t sink fast. Aircraft fuselages are designed to keep air in, and that design helps keep water out. Aviation designers also include systems that can delay sinking. Airbus A-320 cockpits are equipped with a button that seals the lower openings on the plane’s fuselage, such as the avionic ventilation ports and inlet for the ram-air turbine.

5 Training for the unlikely can save the day. Ditching into water is a rare event, but commercial airline crews prepare for it. Likewise, NY Waterway ferry crews train to assist and treat distressed boaters or swimmers. They quickly retrieved 142 of the Airbus’s 155 passengers and crew from the icy water.
 

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