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Aircraft infested by insects forced Heathrow take-offs to be abandoned

Eight aircraft infested by insects caused two take-offs to be abandoned at Heathrow last summer.

Wasp and bee nests blocked speed-measuring pitot probes on six British Airways aircraft and one from Virgin Atlantic, an Air Accidents Investigation Branch (AAIB) report revealed.

A wasp was also spotted inside a probe on another BA aircraft during the same three-week period.

The temporary “surge” was due to fewer flights operating during the pandemic.

Aircraft remaining on the ground for longer periods between flights created an “attractive opportunity” for insects as pitot probes are an “ideal construction site for nests”, the AAIB report said.

 BA crews on board two of the aircraft were forced to abort take-offs while speeding down runways because the blockages caused inaccurate speed readings on cockpit displays.

 Unreliable speed indication is a “serious hazard”, investigators warned.

The high level of insect activity in 2021 could lead to a “larger number of insects emerging in the spring of 2022”, so the risk of more probe blockages “could be significant,” the AAIB warned.

“Proactive habitat management and aircraft monitoring will be required to mitigate the risk. With the move towards ‘greener’ aviation, this may become even more important in the future,” the report added.

“Insects blocking aircraft pitot/static systems is not a new hazard, but one likely exacerbated at Heathrow in 2021 due to the unusually low operational tempo resulting from the Covid-19 pandemic,” the AAIB said.

“Reduced traffic levels and human activity resulted in a surge of insect activity during the pandemic lockdowns. With less aircraft activity, including less noise and jet efflux to deter the insects, the parked aircraft made an attractive opportunity, with the pitot probes providing an ideal construction site for nests.”

The Civil Aviation Authority, Heathrow and affected airlines have taken measures to reduce the risk of the problem reoccurring, such as increasing the frequency of inspections, issuing alerts to aviation firms and using probe covers.

The AAIB report said: “Between 9 June 2021 and 19 July 2021, several aircraft suffered from abnormal pitot/static system events, two of which resulted in rejected take-offs.

“The AAIB investigation identified the cause to be the nesting activity of certain species of wasps and bees within pitot probes.

“Although Heathrow airport and the surrounding area was the focus for these occurrences, detailed information on the environmental factors is provided for the operators of airfields at other locations to take into consideration.

“Safety action has been taken by the CAA and those airline operators affected to reduce the risk of reoccurrence by introducing additional inspections and changes to the use of pitot covers.

“In addition, the airport operator is updating its environmental hazard management plan to take into account the findings of this investigation.”

A BA spokesperson said: “Safety is our highest priority and in each case the flights returned safely to stand.

“Our highly skilled pilots are trained to safely perform this type of standard procedure and practise them regularly.”

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