Gulf Air Flight Makes Emergency Landing in Bahrain

As the investigation into Air France Flight 447 drags on, we look with interest at the investigation of 28 October 2009 Jetstar Airbus A330-200 unreliable airspeed incident.

Jetstar had introduced unreliable airspeed training for cockpit crews shortly before the incident.

The Jetstar A330 was fitted with Goodrich pitot tubes instead of Thales. (Thales were the tubes on 447)

In the Jetstar event, the flight experienced a “rapid and momentary drop” in the airspeed indication, from about 250kt to 50kt and a decrease in standby airspeed. Then autopilot, autothrust and flight directors disconnected. The flight control system reverted to ‘alternate’ law.

Several times, the crew followed procedures for handling unreliable airspeed, then re-engaged autopilot and autothrust, although both automatically disconnected— until all three airspeed indicators were in agreement.

ATSB REPORT SUMMARY
Unreliable airspeed indication – 710 km south of Guam, 28 October 2009, VH-EBA, Airbus A330 202
Investigation Number:AO-2009-065

Summary
On 28 October 2009, an Airbus A330-202 (A330) aircraft, registered VH-EBA (EBA), was being operated as Jetstar flight 12 on a scheduled passenger service from Narita, Japan to Coolangatta, Australia. Soon after entering cloud at 39,000 ft, there was a brief period of disagreement between the aircraft’s three sources of airspeed information. The autopilot, autothrust and flight directors disconnected, a NAV ADR DISAGREE caution message occurred, and the flight control system reverted to alternate law, which meant that some flight envelope protections were no longer available. There was no effect on the aircraft’s flight path, and the flight crew followed the operator’s documented procedures. The airspeed disagreement was due to a temporary obstruction of the captain’s and standby pitot probes, probably due to ice crystals. A similar event occurred on the same aircraft on 15 March 2009.

The rate of unreliable airspeed events involving the make of pitot probes fitted to EBA (Goodrich 0851HL) was substantially lower than for other probes previously approved for fitment to A330/A340 aircraft. However, both of the events involving EBA occurred in environmental conditions outside those specified in the certification requirements for the pitot probes. The French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile (BEA) has recommended the European Aviation Safety Agency (EASA) to review the certification criteria for pitot probes in icing environments.

At the time of the occurrence, most of the operator’s A330 pilots had not received unreliable airspeed training. Most of these pilots had transferred from the operator’s A320 fleet, and the third-party training provider had not included the topic in its A320 endorsement training program, even though it was included in the aircraft manufacturer’s recommended program since 2004.

The operator identified the problem and included unreliable airspeed in its recurrent training program for the A320 from May 2009 and the A330 from October 2009. The training provider included the topic in its endorsement program from July 2010. The operator, training provider and the Civil Aviation Safety Authority all initiated safety action to minimise the likelihood of similar problems in the future.

General Details

Aircraft Details