Plane & Pilot
Tuesday, March 10, 2009

Survivable Ditchings

US Airways Flight 1549 is reminiscent of other successful ditchings

ntsbWithout diminishing in any way the heroic actions of the pilots, flight attendants and passengers on US Airways Flight 1549, which was successfully ditched in the Hudson River after a bird strike on January 15, it’s important to note that most ditchings actually have a high survival rate.
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The airplane touched down on smooth water about 4.7 nm from the end of runway 20. The speed was about 120 knots. The captain and first officer made sure everyone was out, then exited through the cockpit windows. The airplane sank in 15 minutes. Five people drowned.

The airplane was pulled from about 400 feet of water for examination. Investigators found that the cowl flaps on all four engines were fully open. The Civil Aeronautics Board determined that the flight engineer hadn’t closed the engine cowl flaps to their takeoff positions, and it was the open cowl flaps that had disrupted proper airflow, causing the buffeting and control problems.

On October 16, 1956, a Pan American World Airways flight ditched in the Pacific Ocean between Hawaii and San Francisco. All 31 people onboard were rescued, but the airplane wasn’t recovered. After departing from Honolulu at 8:26 p.m. on October 15, the B-377 was cleared to fly at 13,000 feet until reaching a fix over the Pacific, at which point, it would climb to 21,000 feet. Around 1:05 a.m., the fix was reached, and the climb was initiated.

When leveling at 21,000 feet, the airspeed was allowed to increase to 188 knots, and power was reduced to cruise settings. The #1 engine began to overspeed, so power to all engines was further reduced and the flaps were extended to slow the plane. The #1 engine had to be shut down. The prop couldn’t be feathered, and it continued to windmill. The airplane was losing altitude at 1,000 fpm. The extra drag, lack of power and excessive fuel consumption meant that the flight wouldn’t be able to reach San Francisco or return to Honolulu. It was calculated that the airplane could fly only 750 miles, while the distances to San Francisco and Honolulu were more than 1,000 miles. The captain radioed the U.S.

Coast Guard Cutter Pontchartrain, alerting it to the possibility that they’d have to ditch. The Coast Guard kept a vessel on station at a location called “November,” midway between Honolulu and San Francisco. Radar on the Pontchartrain determined that the airplane was approximately 38 nm away, on a bearing of 256 degrees. The flight crew altered course and followed a radio signal to the ship. The crew managed to stop the descent at 5,000 feet while holding a 135-knot airspeed. They discovered that, at full throttle, the #4 engine would only produce partial power. Shortly after 1:30 a.m., the airplane arrived over the Coast Guard ship. The captain decided to descend to 3,000 feet. The ship had fired flares and set out electric lights in the water to establish a ditching track. Because the airplane was maintaining altitude, the captain decided to circle the ship and wait until daylight to attempt the ditching. During the extra time, the passengers were given additional instructions on ditching and evacuation procedures.

A pathway of foam was put down by the ship on a heading of 315 degrees for the ditching. At 6:15 a.m., the airplane touched down with full flaps, at an airspeed of 90 knots with the landing gear retracted. The first water contact was light and was followed by a severe impact, during which the airplane went under water, then bobbed up and stopped. The fuselage broke apart aft of the main cabin door. Everyone got out of the airplane and into rafts. The aircraft sank 10 minutes after touchdown.

Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other NTSB news. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.


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