At 9:14 on the morning of 12 November 2001, American Airlines Flight 587 lifted off from New York’s John F. Kennedy airport bound for Santo Domingo. Many of the 251 passengers were Dominican New Yorkers going home. About 105 seconds later the Airbus A300 hit the ground in Belle Harbor, Queens, without its tail and without its engines. All 260 people aboard and five people on the ground were killed.

It is the second-deadliest aviation accident on US soil. The popular retelling now circulating online gets the essentials right, but it overstates one key point. The tail did not fail because it was weak. It failed because it was pushed far past anything it was designed to take.

A minute and forty seconds behind a 747

Ahead of Flight 587 on runway 31L was Japan Airlines Flight 47, a Boeing 747-400. The tower cautioned the American crew about wake turbulence from the preceding heavy jet, and cleared them for takeoff at 9:13:28. The A300 left the runway at 9:14:29, about one minute and 40 seconds behind the 747. The separation met FAA rules.

Captain Edward States, 42, was handling the radio. First Officer Sten Molin, 34, was flying. As the A300 climbed out over Jamaica Bay it crossed the 747’s wake twice. The first encounter was mild. The second, a few seconds later, rocked the airliner.

Six seconds of rudder

From 9:15:52, Molin pushed the rudder pedals from one side to the other and back again in quick succession. Each reversal swung the tail through the airflow and built up sideslip, and each new input arrived while the previous one was still loading the fin. In about six seconds the side load on the vertical stabilizer rose far beyond its design limit.

At 9:15:58 the composite lugs that attach the fin to the fuselage gave way, and the whole vertical stabilizer and rudder tore off and fell into Jamaica Bay. The NTSB later calculated that the load at the moment of failure was about 203,000 pounds-force, roughly twice the 100,000 pounds-force of the fin’s design envelope. The structure had exceeded its certification requirements. It had simply been asked to carry a load that no airliner fin is built for.

Without its fin the A300 yawed violently. The sideways loads sheared both CF6 engines from the wings; they fell several blocks from the main wreckage, one damaging a petrol station. The stall warning sounded at 9:16:04. The last words on the cockpit voice recorder were an exchange between the two pilots.

The airliner came down on Beach 131st Street in Belle Harbor, destroying several houses. The recorder stopped at 9:16:14.8.

Two months and a day after 9/11

The crash came 62 days after the September 11 attacks, in a city that had not stopped grieving. Belle Harbor itself, home to many firefighters and financial workers, had already lost residents in the Twin Towers. For hours the assumption was that it had happened again.

New York’s three major airports were closed for much of the day. The Port Authority shut the bridges and tunnels between Manhattan and New Jersey, the Empire State Building and United Nations headquarters were evacuated, and Air National Guard fighters flew patrols over the region. By the afternoon, though, the NTSB was leading the investigation, and it soon became clear that there was no sign of a bomb or sabotage.

What the NTSB found

The investigation took almost three years. The NTSB adopted its final report on 26 October 2004, and its conclusion was careful. The wake encounter itself was not dangerous. Had the first officer stopped moving the rudder at any point before the fin broke, the A300 would have levelled out on its own.

The Board did not stop at the pilot. It named two contributing factors. The first was the A300-600’s rudder system: at high speed its pedals needed very little force and travel to command full available rudder, far lighter than pilots might expect, which made it easy to over-control. The second was American Airlines’ Advanced Aircraft Maneuvering Program, whose simulator training exaggerated the effect of wake turbulence and could encourage pilots to use the rudder aggressively to recover from upsets.

Airbus and American argued over where the blame lay, and the pilots’ union argued the rudder’s sensitivity amounted to a design flaw that should have been communicated. The practical lesson for the industry was unambiguous: in a large jet, rapid alternating rudder inputs can break the tail, even at speeds below the manoeuvring speed that pilots had long been told protected them.

Remembering Flight 587

A memorial in Rockaway Park, the community next to Belle Harbor, carries the names of all 265 victims. Every 12 November the names are read aloud there, and a moment of silence is held at 9:16, the time of the crash.

Sources: NTSB, Aircraft Accident Report NTSB/AAR-04/04, “In-Flight Separation of Vertical Stabilizer, American Airlines Flight 587” (2004); NTSB animations; FAA Lessons Learned, N14053; Wikipedia, “American Airlines Flight 587”.