After three incidents over three days at London Heathrow, the British security authorities urged pilots to pay special attention to the speed controls during take-off with suspected pitot jamming by insects.
The individual incidents, which occurred from June 9th to 11th, involved aircraft of different types that were parked every three to seven days at different locations within the hub.
Airspeed deviations led to crew action, says the British Civil Aviation Authority. It has not identified the operators or aircraft concerned.
“Initial feedback suggests that some form of insect infestation may have contributed to these events,” she adds, although a formal investigation is underway by the Aircraft Accident Investigation Department.
“These events may not be isolated at this airport and the timing of the blockades is unknown.”
Operators and maintenance companies are reminded to ensure compliance with specific requirements related to aircraft storage, pre-flight inspections and unreliable airspeed information.
“The crews should be made aware of this potential problem, the importance of the speed controls during take-off taxiing and the measures to be taken in the event of deviations,” said a security bulletin.
Pilots should also be aware of the unreliable speed information for their specific aircraft type in the event that the problem occurs in the air.
Investigators had previously found that insect activity was blocking the pitot probe of an Airbus A321 operated by Wizz Air UK, resulting in a denied high-speed launch in Doncaster last June. The aircraft had been stored for 12 weeks.
Warnings of possible pitot-static port contamination were issued in 2020 by the European Union’s Aviation Safety Agency – to which the CAA was still a part – after concerns about increasing unreliable airspeed or an altitude event when the aircraft were put back into service.
