American Airlines Flight 1572
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An American Airlines MD-83 similar to the one involved in the incident.
|Date||November 12, 1995|
|Site||Windsor Locks, Connecticut|
|Aircraft type||McDonnell Douglas MD-83|
American Airlines Flight 1572, registration N566AA, was a McDonnell Douglas MD-83 flying from Chicago O'Hare that was damaged while landing short of the runway at Hartford's Bradley International Airport on November 12, 1995.
American Airlines Flight 1572 was en route from Chicago O'Hare to Hartford's Bradley International Airport on November 12, 1995. The flight departed O'Hare over 90 minutes late due to bad weather and delayed connecting passengers. En route the flight received an ACARS printout for the weather at Hartford. It noted an altimeter setting (atmospheric pressure) of 29.42 inches of mercury (996 hPa), adding that pressure was falling rapidly in the area. Before making their final approach the pilots were further advised of a wind shear warning and severe thunderstorms for Hartford. Winds were now out of 170° at 29 knots (15 m/s) gusting to 39 knots (20 m/s). The First Officer checked the Automatic Terminal Information Service (ATIS) automated weather broadcast for Hartford which reported an altimeter setting of 29.40 inHg (996 hPa). For reasons unknown he entered this as 29.47 inHg (998 hPa) on the altimeter causing it to read approximately 70 feet (21 m) high. The Captain checked the weather radar before beginning the non-precision approach to runway 15. It showed no convective cells on the aircraft's path and he turned it off. As Flight 1572 began 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. This was likely 838 ft (255 m) due to the incorrect altimeter setting. As the crew began to look for the airport the aircraft continued descending.
At some point during the descent, the sink rate alarm went off immediately followed by a loud thump as the aircraft began shearing off treetops along Peak Mountain ridge. It was later estimated the plane was at 770 ft (230 m) elevation at this point. 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 it 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 with only one minor passenger injury.
The National Transportation Safety Board (NTSB) 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. While turbulence, heavy rain and wind shear affected the aircraft, the crew continued to allow it to descend while searching for the airport.
- American Airlines Flight 1572 incident summary. Aviation-safety.net.
- NTSB report p.15
- NTSB report p.63
- Aircraft Accident Report: Collision with Trees On Final Approach; American Airlines Flight 1572; McDonnell Douglas; MD-83, N566AA; East Granby, Connecticut; November 12, 1995 U.S. National Transportation Safety Board