Waspish problems at Heathrow
David Learmount 27th Jan 2022 Learmount.com
Apparently insect life at London Heathrow airport has vigorously regenerated during the pandemic lockdowns. This has forced the UK Air Accident Investigation Branch (AAIB) to embrace a new science: entomology.
Over about 6 weeks in June and July 2021 two jet crews at Heathrow had to reject take-offs because of unreliable airspeed readings, and several more had to taxi back to their stand because their aircraft’s air data inertial reference unit (ADIRU) had detected anomalies in data from pitot/static sensors. Aircraft involved included Airbus A320 and A330 series, and Boeing 777 and 787 series.
The main reason, of course, is insects (mainly wasps, it seems) nesting in pitot tubes. This is not a new phenomenon, but the summer 2021 burst of particularly intense insect activity raises numerous questions beyond the obvious flight safety ones. As the AAIB puts it: “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. ”
In the old days they’d just have sprayed the place with DDT.
The question is, what prompted this “infestation”? The AAIB explains that it appears to be the result of “reduced traffic levels and human activity resulting in a surge of insect breeding 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 agency points out that the Heathrow area is an air pollution hot spot not only because of air traffic, but heavy local motorway and urban road traffic also. All of these pollution contributory factors, however, were considerably reduced during the lockdown periods of 2020 and 2021.
Perhaps in 2022, as the pandemic threat recedes and air movements increase, aviation itself will chase the insects away? The AAIB’s recently gained entomological expertise has led it to believe this will not be so – or certainly not this year: “The high level of insect activity in 2021 could lead to a larger number of insects emerging in the spring of 2022. Therefore, even though traffic levels and aircraft utilisation are expected to increase in 2022, the seasonal risk of insects blocking pitot probes could be significant.”
An additional factor encouraging insects to make their nests in aircraft has been simple opportunity: the larger numbers of aircraft parked for longer periods. Pilots and operators of light aircraft operating out of sleepy country airfields have long known that their pre-flight walk-rounds must include inspection of any crevices or hideaways. Even birds have been discovered nesting in engine bays, having found their way in via the cooling air intakes.
Despite the fact that most pilots have suffered a pandemic-induced loss of flying practice, none of this rash of insect-caused unreliable airspeed incidents at Heathrow has led to an accident. To ensure this remains true, the AAIB has recommended an “enhanced use of pitot covers or additional pre-flight inspections.” The airlines and their crews were already doing that!
This issue remains current as far as the AAIB is concerned. It is working with the Natural History Museum to identify the precise wasp species involved in aircraft infestations, their over-winter domiciles, spring nesting, mating and larvae-hatching patterns.
When they have learned all this, they then have to decide what to do about the phenomenon.
Presumably without resorting to blanket pesticide use.