A new aviation challenge: wasps

A small insect that managed to bypass Australia’s strict biosecurity regulations is now multiplying and posing a risk to aircraft safety at Brisbane Airport.

Originally from Central and South America and the Caribbean, the keyhole wasp first made its presence felt at the airport in 2013, forcing an Etihad Airways A330 to return shortly after takeoff en route to Singapore.

After the plane landed, maintenance crews discovered that the pilot’s pitot tube – the external sensor used to measure airspeed – was nearly entirely clogged with mud, as per a report from the Australian Transport Safety Bureau.

Pitot tubes are the ideal nesting spot for wasps, and in this case, the Etihad aircraft had only been on the ground for two hours before the flight was canceled.

Alan House, an ecologist from Eco Logical Australia, shared reports from Brisbane ground crew, stating that a plane could land and within just two or three minutes, a wasp might already be circling the nose of the aircraft, inspecting the probe.

House collaborated with experts from Brisbane Airport, Australian airline Qantas, and the environmental consultancy Ecosure to conduct one of the first studies examining the effect of wasps on pitot tubes. The study, commissioned by Brisbane Airport Corporation, was published this week in the open-access journal PLOS ONE.

Researchers warn that without proper management, there’s a real risk of wasps spreading to other Australian airports and even to neighboring countries with the right semi-tropical conditions for the species to thrive.

“After conducting some research, we realized this wasn’t just a minor nuisance, where you'd simply clean out the tubes and shoo away the wasps. This issue could actually cause serious accidents,” House explained.

An Essential Instrument

Pitot tubes, located at the front of airplanes, are crucial for providing vital information to the cockpit, such as the speed of air passing through. This data helps pilots monitor the plane's velocity—too slow could lead to a stall, while too fast could result in other mechanical failures.

If the pitot tubes malfunction, the plane, like the Etihad A330, will automatically switch to manual mode, requiring pilots to take control. This is what occurred with the Etihad flight, leading to its return.

While there have been no major accidents at Brisbane Airport linked to the wasps, similar incidents at other locations have been attributed to the insect.

For example, Birgenair Flight 301 crashed off the coast of the Dominican Republic in February 1996, resulting in the deaths of 189 people. The accident report noted that the 'likely cause' of the blockage in the pitot tube was 'mud and/or debris from a small insect' that had entered while the aircraft was on the ground.

In 2018, Australia’s Civil Aviation Safety Authority (CASA) issued a warning to pilots, airlines, and airports about the risks posed by wasp infestations. Blockages in pitot tubes could lead to a complete loss of airspeed and altitude readings, which the alert described as 'hazardous'.

CASA recommended that airlines cover pitot tubes while stationed at Brisbane Airport, but this is not a mandatory practice, which is why blockages continue to occur. The Brisbane Airport study reported 26 incidents between November 2013 and April 2019.

Cunning wasps

The first sightings of keyhole wasps in Australia were reported at the Port of Brisbane in 2010, although they may have arrived as early as 2006. How they got to the country is still unclear, but researchers believe they likely came by ship, according to House.

These wasps are believed to have been at Brisbane Airport since 2012. While they have not spread to other major cities in Australia, they have been spotted at Emerald Airport, a small regional hub located over 800 kilometers (500 miles) away, as per CASA.

For the study, researchers used 3D printing technology to create replica pitot tubes from various aircraft, including Boeing 737s, 747s, Airbus A330s, and smaller Dash 8 regional planes. The replicas were placed at four different spots around the airport and observed over a 39-month period.

During this time, 93 instances of fully blocked pitot tubes were recorded, with almost all of these incidents occurring during the warmer months from November to May.

According to Jackson Ring, co-author of the study and wildlife management coordinator at Brisbane Airport, most of the nests were found near the grassed areas. The wasps gather caterpillars from the grass and stuff them into the pitot tubes to feed their larvae.

To reduce wasp activity, wildlife managers are applying targeted, organic pesticides to eliminate the caterpillars. This strategy has successfully cut down wasp activity around both the international and domestic terminals by 50%, Ring reported.

Ring explained that they treat approximately 120 hectares (1.2 square kilometers) of the airfield, which helps remove the food source and make areas where planes are parked less attractive to the wasps.

Introducing natural predators, such as birds, isn’t an option due to obvious concerns. Before the wasps appeared, Ring’s focus was on preventing wildlife from approaching planes, to reduce the risk of bird strikes and other hazardous encounters.

Is it possible to completely eliminate the wasps?

The wasp is not considered an agricultural threat nor does it spread diseases to humans. Despite its unwelcome presence, there is no government initiative to eradicate it, according to House.

The wasp is a highly adaptable creature, with no shortage of places to breed.

'It can construct its own nest, reuse abandoned nests from other mud wasps, or occupy any available space,' House said. 'There are countless spots like that throughout the airport and pretty much everywhere else.'

'They’re incredibly focused,' House continued. 'All they need is a spot to nest, a caterpillar to store, an egg to lay, and then they seal it up.'

Like many airports worldwide, Brisbane Airport saw a sharp decline in traffic during the pandemic. Since July, international flights to Australia have been restricted by caps on returning travelers, and state borders have been closed to control local outbreaks. Planes remained grounded for months, with pitot tubes covered to prevent wasp infestations.

However, with the lifting of domestic border restrictions on Tuesday, air traffic will pick up again, increasing the likelihood of wasp-related issues as more planes arrive and depart.

The study reveals that keyhole wasps are also found in the southern United States, as well as several Pacific Islands, including Hawaii, Polynesia, Micronesia, and Japan.

Researchers are collaborating with airport authorities in Papua New Guinea and Fiji, where similar incidents have been reported. They’ve also sent 3D-printed probes and equipment to Honolulu for related studies.

House emphasized that researchers didn’t want to create the impression that flying out of Brisbane is unsafe. In fact, he noted, it’s likely safer now than in previous years when their understanding of the insect was more limited.

While small in size, House pointed out, the threat posed by the keyhole wasp to aviation should not be underestimated.

“Wildlife management at airports, particularly regarding birds, receives significant global attention because of their obvious risk to aviation,” House explained.

“Wasps, on the other hand, are often seen as a minor threat. The likelihood of an incident is low, but it’s still a possibility,” House added.