Both Engines Fail Over New York

Birds at 2,818 feet over New York

Two thousand eight hundred feet above New York City. The airliner has been in the air for about a minute and a half. The captain says one word: "birds".

One second later, both engines lose almost all of their thrust. From here the flight has three and a half minutes left in the air. It ends on the Hudson River. All one hundred and fifty-five people on board survive.

Flight 1549 leaves LaGuardia for Charlotte

This film is built from the investigators' own record: the National Transportation Safety Board's accident report, adopted on the fourth of May, twenty ten, and the public docket behind it. The times, heights and words come from the flight data, the radar and the cockpit voice recorder.

“birds.”

p. 169, transcript, NTSB AAR-10/03, adopted 4 May 2010

On the fifteenth of January, twenty oh nine, US Airways flight fifteen forty-nine was cleared for take-off from runway four at LaGuardia, bound for Charlotte, North Carolina. The aircraft was an Airbus A three twenty, with two CFM fifty-six engines.

On board were one hundred and fifty passengers, including a child on a lap, and five crew.

In the left seat, the captain, fifty-seven, with nearly twenty thousand flying hours, more than four and a half thousand of them on this type. In the right seat, the first officer, forty-nine, with more than fifteen thousand hours. Thirty-seven of them were on the A three twenty. He had qualified on it fifteen days earlier. It was their first trip together.

Clear and cold: ten miles of visibility, minus six degrees Celsius. The first officer was flying.

Both engines lose almost all thrust

At three twenty-seven, climbing through about two and a half thousand feet, the aircraft's path crossed a string of unidentified radar echoes. They were not on the departure controller's screen. He had set it to show only echoes that behaved like aircraft, and the investigators found that choice appropriate.

At eleven seconds past three twenty-seven, the cockpit microphone records thumps, and a shudder. The left engine falls from eighty-two per cent fan speed to thirty-five. The right falls to fifteen. The first officer: "uh oh." The captain: "both of 'em rolling back".

Ten seconds after the strike, the captain starts the auxiliary power unit, an extra source of electrical power in the tail. It was a step the crew never reached on the checklist. The investigators found it kept a main source of electrical power available, and with it the flight control protections, one of which prevents a stall.

Two seconds later: "my aircraft." The captain takes the controls. The first officer takes the checklist.

With almost no thrust, the aircraft still climbs for a few seconds, trading speed for height. Nineteen seconds after the strike it tops out at about three thousand and sixty feet.

LaGuardia, Teterboro or the Hudson

Twenty-two seconds after the strike, the captain calls departure control: "hit birds", "we're turning back towards LaGuardia". His first words did not get through. Another pilot was transmitting at the same moment.

“we're unable. we may end up in the Hudson.”

p. 174, transcript, NTSB AAR-10/03, adopted 4 May 2010

The controller turns the flight left, back toward the airport, and tells the tower to stop departures.

The first officer works from the engine dual failure checklist, three pages long. Airbus had written it for a failure above twenty thousand feet. It had not considered a checklist for a failure this low.

One early step asks for three hundred knots, the best speed for restarting the engines in flight. The first officer reads it out: "we don't have that".

Fifty-four seconds after the strike, the controller offers runway one three at LaGuardia. Five seconds later the captain answers: "we're unable. we may end up in the Hudson". The aircraft has already lost about fourteen hundred feet.

The captain later told investigators that turning back would have been an "irrevocable choice": if they fell short, there would be nowhere else to go. A direct return would also have crossed Manhattan.

About a hundred seconds after the strike, at thirteen hundred feet, he asks what lies to the right: "maybe Teterboro?" The controller offers runway one there. Thirty-five seconds after his question: "we can't do it". The captain's later words: "too far away, too low, and too slow".

Three seconds after that, at about seven hundred feet: "we're gonna be in the Hudson". The river was the one place, in his words, "long enough, smooth enough, and wide enough".

Investigators later flew the problem in simulators in Toulouse. Pilots briefed in advance, who turned for a runway the instant the thrust went, made it in eight of fifteen runs. The one run that allowed thirty-five seconds to understand the failure and decide did not make it. The board found the river gave the highest chance of survival.

No restart could bring the thrust back

All this time, the first officer had been working the restart steps: engine switches off, a wait, and on again. The engines were still turning, and still burning fuel. But in each one, birds had broken guide vanes at the front of the core, and the pieces had damaged the compressors behind them. No restart could bring the thrust back. The restart attempts took thirty to forty seconds. Nothing on the flight deck could tell the crew the engines were beyond restarting.

Two minutes after the strike, the captain speaks to the cabin: "this is the Captain brace for impact". Ninety-two seconds remain.

Fifteen alerts on the way down the river

The aircraft is over the river now, heading south between New Jersey and Manhattan. The warning system calls "too low, terrain", and then "pull up", again and again. Fifteen alerts in eighty-five seconds.

“got any ideas?”

p. 184, transcript, NTSB AAR-10/03, adopted 4 May 2010

At about two hundred and seventy feet the flaps go to position two. The first officer asks, "you want more?" The captain: "no lets stay at two". The checklist's water landing page called for position three. The crew never reached that page. The board found the choice of two reasonable.

Twenty-two seconds before touchdown, the captain asks: "got any ideas?" The first officer: "actually not".

In the last two hundred feet, the speed sits fifteen to nineteen knots below the speed that keeps a set margin above the stall. In the last two seconds the captain pulls the sidestick fully back. The protection system will not let the wing stall, and it limits how far the nose comes up.

At three thirty and forty-three seconds, the aircraft touches the Hudson, near the ferry terminal at Weehawken, New Jersey. One hundred and twenty-five knots, nose up nine and a half degrees. Three and a half minutes after the birds. The board calls it a ditching: a landing on water that the crew chose, with the aircraft under control.

The ditching, 3 1/2 minutes after the birds

When the A three twenty was certified for landing on water, the certification assumed a descent of three and a half feet a second, with engine power available. Flight fifteen forty-nine came down at twelve and a half.

The impact broke the lower rear of the fuselage, and the river came in at the back.

Out through the front doors and onto the wings

Fifteen seconds after touchdown, the left overwing exits were open. The front doors followed, twenty-three and twenty-eight seconds after. Water was coming in at the back, so the rear slides could not be used. The flight attendants sent people forward, to the front doors and the wings.

This aircraft happened to carry equipment for flights far out over water, though this route did not need it. About sixty-four people used its two front slides as rafts.

The river was five degrees Celsius. The air was below freezing. The captain and first officer checked that no one was left in the cabin, then stepped onto the front left raft.

The first ferry arrived about four minutes after touchdown. Seven ferries, a fire department boat and two Coast Guard boats took people off the wings and rafts. The last boat with the last passengers left twenty-four minutes after touchdown. Five people were seriously hurt: one flight attendant and four passengers. No one died.

Every usable DNA sample was Canada goose

Investigators sent feathers and tissue from the engines and the airframe to the Smithsonian Institution's feather identification laboratory. Every sample with usable DNA matched one species: the Canada goose.

“the decision-making of the flight crewmembers and their crew resource management during the accident sequence;”

p. 123, NTSB AAR-10/03, adopted 4 May 2010

There were male and female geese in the left engine, and only male remains in the right. Each engine took in at least two birds of about eight pounds.

Chemical tests found the feathers resembled geese that migrate, and differed from the geese that live around New York all year.

The engine's certification tests used a single four pound bird, and volleys of birds weighing one and a half pounds. The board found these geese well beyond those standards, in size and in number.

Of the large airliners destroyed by bird strikes since nineteen sixty, ninety-three per cent were hit below about five hundred feet, near an airport. This one was at almost three thousand feet. The board concluded that a bird strike does not need to be typical to be hazardous.

The probable cause, in the board's words

The board's finding of probable cause, in its own words: "the ingestion of large birds into each engine, which resulted in an almost total loss of thrust in both engines and the subsequent ditching on the Hudson River." "Contributing to the fuselage damage and resulting unavailability of the aft slide rafts were one, the Federal Aviation Administration's approval of ditching certification without determining whether pilots could attain the ditching parameters without engine thrust, two, the lack of industry flight crew training and guidance on ditching techniques, and three, the captain's resulting difficulty maintaining his intended airspeed on final approach due to the task saturation resulting from the emergency situation."

With its report, the board made thirty-four new safety recommendations. Among them: a checklist for a dual engine failure at low altitude, and training for one. Technology that tells pilots whether an engine can still run. And proof that pilots can meet an aircraft's figures for a water landing with no engine power, without exceptional skill or strength.

The board named four things that contributed to survival: the crew's decisions and teamwork, the rafts this aircraft happened to carry, the cabin crew's evacuation, and rescuers close at hand. It also wrote that the success mostly came from fortunate circumstances: good visibility, calm water, a very experienced crew, and boats nearby.

Lift-off to the river: about five minutes. The strike to the river: three and a half minutes, from three thousand feet.

All one hundred and fifty-five people on board lived. Source: National Transportation Safety Board.