EASA has issued the following Safety Information Bulletin to all commercial operators to raise awareness of possible unreliable airspeed indications related to pitot static systems due to the Air France Crash:
Background:
During the recent accident of an A330 into the Atlantic Ocean on 01 June 2009, and without prejudging the final outcome of the investigation, a discrepancy between the different measured airspeeds was reported. There have been a number of occurrences of unreliable airspeed indications or misleading air data information. The root cause of this may be due to, but is not limited to, inappropriate maintenance, contamination by small objects or materials on the ground or in the air, extreme environmental conditions producing icing outside the certification envelope of the probes or large amount of water ingestion.
Description:
The primary purpose of the pitot-static system is to provide the flight crew with airspeed information, required to safely control the aircraft. As noted above, the origins of potential pitot-static system malfunctions are numerous and cannot be totally excluded in the operational context. The Aircraft Flight Manuals and/or Flight Crew Operating Manuals include procedures for unreliable airspeed indication (Air data system misleading information) and these should be well known by flight crews. Correct application of these procedures by flight crews may be crucial for assuring the safety of the aircraft when such Pitot-static malfunctions occur.
Recommendations:
Operators should ensure that flight crews have proper knowledge and proficiency: – To detect and to identify unreliable airspeed indication. – To apply immediate and conservative actions for ensuring short term safe flight control, in accordance with the manufacturer procedures developed for the specific aircraft; the use of memory items should be considered. – To apply procedures for the safe continuation of a flight with unreliable airspeed indication up to a safe landing. Familiarization of flight crews with unreliable airspeed indication procedures should be provided through adequate training. Flight crew knowledge and proficiency should be checked on a regular basis.
