Thursday, June 25, 2009

NTSB investigating two recent Airbus A330 'speed and altitude indication anomalies'

by B. N. Sullivan

NTSB logoThe afternoon, the U.S. National Transportation Safety Board (NTSB) issued an advisory announcing the investigation of "two recent incidents in which airspeed and altitude indications in the cockpits of Airbus A-330 aircraft may have malfunctioned."

The NTSB advisory describes the incidents as follows:
The first incident occurred May 21, 2009, when TAM Airlines flight 8091 (Brazilian registration PT-MVB) flying from Miami, Florida to Sao Paulo, Brazil, experienced a loss of primary speed and altitude information while in cruise flight. Initial reports indicate that the flight crew noted an abrupt drop in indicated outside air temperature, followed by the loss of the Air Data Reference System and disconnections of the autopilot and autothrust, along with the loss of speed and altitude information. The flight crew used backup instruments and primary data was restored in about 5 minutes. The flight landed at Sao Paulo with no further incident and there were no injuries and damage.

The Safety Board has become aware of another possibly similar incident that occurred on June 23 on a Northwest Airlines A-330 (registration unknown) flying between Hong Kong and Tokyo. The aircraft landed safely in Tokyo; no injuries or damage was reported. Data recorder information, Aircraft Condition Monitoring System messages, crew statements and weather information are being collected by NTSB investigators.

Further information on both incidents will be released when it becomes available.
For what it's worth, a chilling story about a Delta (i.e., Northwest) A330-300 incident has appeared on several aviation message boards over the past day or two. I tend to view undocumented stories on message boards with some skepticism, and as regular readers of Aircrew Buzz know, I am not inclined to report rumors. But I must admit that when today's NTSB advisory showed up in my email inbox my first response was to revisit one of the message boards where I had seen the Delta A330 story to see if my memory of what I had read was correct.

The story described a marked drop in indicated outside air temperature, the loss of airspeed and altitude information, and the sudden disengagement of the autopilot and autothrust. The failure was said to have lasted about three minutes. The details of the story (aircraft type, carrier, route, date) did indeed match those in the above NTSB advisory. The source of the message board story is purported to be a crew member from the flight in question.

Fortunately that story had a favorable outcome, as did the TAM flight mentioned in the NTSB advisory. One cannot help but wonder if indeed something similar happened to Air France Flight 447, but with a different and hugely tragic outcome.

Let's hope that the NTSB, the French BEA, and other agencies will be able to get to the bottom of these apparently similar incidents before we have another occurrence that is irrecoverable.