American Airlines Flight 1572
An American Airlines MD-83 similar to the one involved in the incident.
|Date||November 12, 1995|
|Summary||Controlled flight into terrain|
|Site||Windsor Locks, Connecticut|
|Aircraft type||McDonnell Douglas MD-83|
American Airlines Flight 1572 was a flight from Chicago O'Hare International Airport to Bradley International Airport on November 12, 1995. The McDonnell Douglas MD-83 struck trees and an instrument landing system (ILS) antenna during landing, causing $9 million in damage to the aircraft.:1, 11
American Airlines Flight 1572 was a regularly scheduled passenger flight from O'Hare International Airport in Chicago, Illinois to Bradley International Airport in Hartford, Connecticut. On November 12, 1995, Flight 1572 was operated using a McDonnell Douglas MD-83, a twin-engine, narrow-body jet airliner (registration N566AA).:1 The aircraft was equipped with two Pratt & Whitney JT8D-219 engines.:13 The MD-83 had accumulated a total of 27,628 flight hours at the time of the accident.:13
Flight 1572 was scheduled to depart from O'Hare at 21:25 Eastern Standard Time. However, because of bad weather and delayed connecting passengers, the flight was delayed and did not depart until 23:05. While en route to Hartford, the flight crew received an ACARS printout for the weather at Hartford. It noted an altimeter setting (reference atmospheric pressure) of 29.42 inches of mercury (996 hPa), adding that pressure was falling rapidly in the area. The flight cruised uneventfully from Chicago to Hartford, other than changing from 33,000 ft (10,000 m) to 35,000 ft (11,000 m) to avoid reported turbulence.:2
While on descent into Hartford, the pilots received a weather update at 00:30 that included a warning of wind shear and severe thunderstorms at Bradley.:2-3 At 00:32, Flight 1572 was instructed by air traffic controllers to descend to 19,000 ft (5,800 m).:3 At 00:33, controllers advised Flight 1572 to descend to 11,000 ft (3,400 m) and advised the flight to use an altimeter setting of 29.40 inHg (996 hPa) for Bradley. At 00:34, the first officer checked the Automatic Terminal Information Service (ATIS) automated weather broadcast for Hartford, and noted to the captain that the most recent ATIS broadcast was about 90 minutes old. For reasons unknown, the first officer entered 29.47 inHg (998 hPa) on the altimeter causing it to read approximately 70 feet (21 m) high.:3 The captain checked the aircraft's weather radar before beginning the non-precision approach to runway 15. Seeing no convective cells on the aircraft's path, he then turned the radar off.:5
At 00:49, while Flight 1572 was beginning its final approach, the crew was advised that the control tower was closing temporarily due to severe weather buckling a window inside the cab. The tower supervisor remained behind to assist the flight. The captain noticed the autopilot was having difficulty maintaining altitude and heading in the buffeting winds. Five miles from the airport the aircraft encountered heavy rain and some turbulence. The flight continued descending to 908 ft (277 m), the minimum descent altitude (MDA) for the approach. As the crew began to look for the airport, the aircraft continued descending.
At 00:51, winds at Bradley were measured as 170° at 25 knots (13 m/s), gusting to 40 knots (21 m/s), with an altimeter setting of 29.35 inHg (994 hPa) and falling rapidly. This information was not transmitted to the Bradley control tower until 00:57 and was not made available to the flight crew before landing.:14
At 00:55, the sink rate alarm went off, followed seconds later by a loud thump as the aircraft began shearing off treetops along Peak Mountain ridge.:6 These trees were on a ridge with a ground elevation of 770 ft (230 m), and the treetops were struck at a height of 770 ft (230 m). The captain advanced the throttles to full power, but the trees had been ingested into the engines causing them to flame out and shut down. The captain immediately lowered flaps to 40° hoping it would momentarily cause the aircraft to "balloon" upwards. While not standard operating procedure, this worked to a limited extent until the aircraft clipped a tree near the end of the runway. It then impacted the runway 33 ILS antenna equipment at the approach end of runway 15 before rolling to a stop.:10
The accident resulted in one minor injury to a passenger; the other 72 passengers and all 5 crew members escaped without injury. The accident resulted in $9 million in damage to the aircraft and over $74,000 in damage to airport equipment.:11
The National Transportation Safety Board investigated the accident.
The investigation cited several causes for this accident. It faulted the Federal Aviation Administration (FAA) for designing the approach to runway 15 without taking the ridgeline into consideration. The new approach, which factors in the terrain, has increased the MDA to 1,320 ft (400 m). However it cited pilot error as the primary cause due to an incorrect altimeter setting combined with the crew's failure to level off at the MDA. The report also noted since pressure was falling rapidly, the crew should have requested a more recent altimeter setting from the tower—the ATIS broadcast is normally updated hourly or whenever weather conditions change, and the first officer had noted that the ATIS recording was over 90 minutes old.:63 While turbulence, heavy rain and wind shear affected the aircraft, the crew continued to allow it to descend while searching for the airport.
- "Aircraft Accident Report: Collision with Trees On Final Approach; American Airlines Flight 1572; McDonnell Douglas; MD-83, N566AA; East Granby, Connecticut; November 12, 1995" (PDF). National Transportation Safety Board. November 13, 1996. NTSB/AAR-96/05. Retrieved September 8, 2016.