Dans la série des what if : avec une décision instantannée le retour à la Guardia semblait possible... mais l'amerissage présentait au final les meilleures chances de succès
WASHINGTON — Everybody got out alive when US Airways Flight 1549 hit the Hudson River 16 months ago, but only because of a “perfect storm” of happy circumstances that went beyond the actions of the crew, the chairwoman of the National Transportation Safety Board said Tuesday as the board made 33 recommendations for safety improvements.
A key factor, according to board experts, was that the airplane was equipped for extended flying over water, although that was not required for its intended route, from La Guardia Airport to Charlotte, N.C. As a result, it carried four inflatable devices meant to be available as evacuation slides and as rafts, and the two that worked were a safe haven for 64 passengers and crew members; without the rafts, some of them would probably have died in the 41-degree water, board experts said.
“If the visibility had been poor; if the flight had simply met, rather than exceeded, safety equipment standards; if the incident took place over open water where rescue vessels were not at hand; if even a single element had changed, the ditching could have ended not as a miracle but as a tragedy,” said Deborah A.P. Hersman, chairwoman of the board, which met on Tuesday to approve a final report on the crash landing.
Ms. Hersman said “the heroism of the flight crew was a necessary, but not sufficient element.”
The number of flight safety recommendations was extraordinary considering that all 155 people on board walked away, with only five serious injuries, when the plane, an Airbus A320, sucked geese into both engines shortly after takeoff on Jan. 15, 2009, and was brought down by the crew into the Hudson River.
But the crash shined a spotlight on a previously hypothetical area of airplane regulation: how to assure safety for an airplane that the crew must bring down in water. The Federal Aviation Administration had never tested the airplane manufacturer’s assumption that a pilot could bring it down at a rate of about three and a half feet per second; this plane came down at about 13 feet per second, causing severe hull damage that resulted in the plane’s taking on water, the board said.
There was renewed praise at the hearing for the captain, Chesley B. Sullenberger III, and the first officer, Jeffrey B. Skiles, but the board found that it was “possible but unlikely” that pilots could set the plane down as the manufacturer had assumed.
The pilots were trained to follow a checklist that focused on restarting the engines, but nothing in the cockpit told them that the engines were damaged beyond hope, board experts said. The experts called for cockpit instruments that would give more detailed information to pilots on the condition of their engines and also recommended new checklists based on low-altitude engine failure; the one the US Airways pilots had was for a high-altitude failure, in which case more time would have been available.
Board experts said that the damage on touchdown — which let water flow into the back of the fuselage and submerged the rear doors, rendering their slide-rafts useless — might be typical in such cases and recommended that rafts be located where they were more likely to be accessible. The experts also found that passengers had trouble finding the life vests and then putting them on.
And approval of the airplane’s design was based on the idea that the over-wing exits would not be used. But the Association of Flight Attendants pointed out in a document the board released on Tuesday that in this crash, passengers in the emergency rows exercised “self help” and opened the over-wing exits. Because the wing exits had only slides, and not slide-rafts like the doors, passengers who exited through those openings could have been marooned in the frigid water if rescue boats had not arrived before the plane sank.
But the passengers evidently assumed that the inflatable slides on the wings, designed to let them slide safely to ground level, were also rafts. “It kept flipping over,” one passenger, Tess Sosa, who took the train from New York to watch the hearing, recalled on Tuesday. Standing on the right wing as the water rose, she and other passengers were certain the slide was also a raft, she said.
Ms. Sosa, who now lives in East Hampton, N.Y., had her son Damian, then 10 months old, on her lap. She said the accident persuaded her that babies should not be permitted on laps — that they needed their own seats and appropriate safety restraints. This was not among the recommendations on Tuesday, but board members agreed they would hold a session soon on safety for “lap children.”
Documents and comments by experts reasserted the idea that Captain Sullenberger’s decision to put the plane in the water was sound. Some pilots and experts have noted that from the point the engines quit, the runways of La Guardia may have been closer than the eventual touchdown point on the Hudson, but that it may have been impossible for the crew to know that at the time.
Clay McConnell, a spokesman for Airbus, said that the recommendations were “reasonable” and that his company was already working on two of them: better checklists and a change in the design of a floor beam. A beam at the back of the plane popped out of the floor and gashed the shin of the flight attendant there.
Les Dorr Jr., a spokesman for the F.A.A., said that his agency had no immediate comment on the details of the recommendation but that the agency agreed with the board’s broad approach, which included consideration of the airplane itself, changes at airports and changes in managing birds. One recommendation was to work on lights or other systems that could be put on planes to make the planes more conspicuous to birds.
A priori pas mal de boulot à prévoir sur les check list et quelques retours d'expérience intéressant sur la position des embarcations de secours (pas obligatoires pour des vols transcontinentaux : là je rêve !!!) en lien avec une attitude d'atterissage avec une grosse incidence et des dégats à l'atterissage causant des entrées d'eau arrière.
Petites modifs structurales à prévoir sur l'320 dans le secteur train avant pour éviter qu'une poutrelle (beam) ne défonce le plancher de la cabine.