US Airways Flight 1549 - Accident Investigation

Accident Investigation

Shortly after the event, Federal Aviation Administration (FAA) spokeswoman Laura Brown said that the plane may have been hit by birds. A National Transportation Safety Board (NTSB) Go Team (typically comprising specialists in fields relating to the incident), led by Senior Air Safety Investigator Robert Benzon, was dispatched to New York. The preliminary report of the incident, published on January 16, states that the aircraft went down following a bird strike. This conclusion, and the simultaneous loss of thrust in both engines, was confirmed by preliminary analysis of the cockpit voice recorder and the flight data recorder, both of which were recovered by the NTSB when the aircraft was lifted out of the river on January 18.

The next day, reports surfaced that the same airplane and same flight had experienced a similar but less severe compressor stall on January 13. During that flight, passengers were told they might have to make an emergency landing. However, the affected engine was restarted and the flight continued to Charlotte. The NTSB later reported that this engine surge had been caused by a faulty temperature sensor, which was replaced, and that the engine was undamaged by the event, which allowed the plane to return to service.

On January 21, the NTSB noted that organic debris, including a single feather, as well as evidence of soft-body damage, was found in the right engine. The left engine was recovered from the river on January 23 and, like the right engine, was missing a large portion of its housing. On initial examination the NTSB reported that while missing obvious organic matter, it too had evidence of soft body impact, and "had dents on both the spinner and inlet lip of the engine cowling. Five booster inlet guide vanes are fractured and eight outlet guide vanes are missing." Both engines were to be sent to the manufacturer's Cincinnati, Ohio, facility for teardown and examination. On January 31, the plane was moved to a secure storage facility in Kearny, New Jersey, for the remainder of the investigation. The NTSB confirmed that bird remains had been found in both engines. The bird debris was later identified, through DNA testing, as the remains of Canada Geese, the typical weights of which are well above the limits of impact for which the engines were designed.

On February 5, the FAA released audio tape recordings and transcripts of its internal and broadcast ATC communications relating to the accident. The entire exchange between Flight 1549 and air traffic control relating to the emergency lasted less than two minutes.

The A320 had been assembled by the Airbus Division of the European aerospace consortium EADS, at the Airbus headquarters manufacturing facilities in Toulouse, France; therefore, under the provisions of ICAO Annex 13, both the European Aviation Safety Agency (the European counterpart of the FAA) and the Bureau d'Enquêtes et d'Analyses pour la sécurité de l'Aviation Civile (the French counterpart of the NTSB) became active participants in the accident investigation, with technical assistance provided by Airbus Industrie and GE Aviation/Snecma as manufacturers of the airframe and engines respectively.

The NTSB ran a series of tests using Airbus simulators in France, to see if Flight 1549 could have returned safely to their choice of LGA, either runway 13 or 22, or TEB runway 19. The test pilots were fully briefed on the series of events and maneuvers. The test pilots were only able to return successfully to either airport in eight of 15 attempts. The NTSB report noted that these test conditions were unrealistic: "The immediate turn made by the pilots during the simulations did not reflect or account for real-world considerations..." A single follow-up simulation was conducted where the pilot was delayed by 35 seconds: He crashed trying to return to LGA runway 22.

Flight 1549 is the fifth take-off/departure phase accident at LaGuardia resulting in the write off of an airframe for a commercial air carrier since the field opened in 1939. Of those, it is the third involving the hull loss of a US Airways/USAir plane.

On May 4, 2010, the NTSB released a statement which credited the accident outcome to the fact that the aircraft was carrying safety equipment in excess of that mandated for the flight, and excellent cockpit resource management among the flight crew. Contributing factors were the good visibility and fast response from the various ferry operators. Captain Sullenberger's decision to ditch in the Hudson River was validated by the NTSB.

On May 28, 2010, the NTSB published its final report into the accident. It determined the probable cause of the accident to be "the ingestion of large birds into each engine, which resulted in an almost total loss of thrust in both engines".