The tragic plane crash of a Boeing 757 in 1996 that killed 189 passengers and crew was the result of a wasp’s mud nest built in one of the aircrafts pitot probes—slender tubes used by the pilot and co-pilot to measure the outside flow speed enabling them to calculate airspeed used to safely fly the aircraft. Now, nearly 25 years later, these menacing mud nest building wasps are plaguing Brisbane Airport in Australia, so far resulting in 26 incidents between November 2013 and April 2019 in which flights had to be either delayed, rerouted, or emergency landed due to keyhole wasps building mud nests in aircrafts pitot probes. These invasive wasps are found not only in Australia, but as well in Florida, Texas, Arizona, Micronesia, Japan, and Hawai’i, making this threat important to recognize now before one of our airports is too plagued with these mud nest building wasps.
Keyhole wasps (Pachodynerus nasidens) are stinging wasps native to South and Central America and the Caribbean, only arriving in Australia recently in 2010. They were first reported in Hawai’i in 1911. Stinging wasps are a common fear—they are known to be territorial and typically aggressive to humans and other animals, especially when near their nests, and can be further dangerous when in packs. Keyhole wasps are not particularly aggressive unless provoked, and they are mostly solitary, but their most terrifying and unique aspect is their fervent mud-nesting behavior: they are extremely adaptive to new opportunities for nesting in novel environments and in increasing urban areas they have become efficient in building nests in man-made cavities such as window crevices, keyholes, electrical sockets, and most alarmingly, in aircraft pitot probes. Keyhole wasps’ native range is grasslands and swamps and when building nests have been shown to peak in the summer months, therefore, Hawai’i’s summer season kau from May to October could prove an ideal six months for these wasps and troubling for us.
The admirable efficiency of keyhole wasps in building their mud nests at Brisbane Airport is showcased by the speed and promptness in which a scouting keyhole wasp becomes aware of a newly landed aircraft in as short as three minutes of landing. Additionally, the shortest time recorded at Brisbane needed for the completion of a nest was five hours, but even an incomplete nest is cause for a flight delay, reroute, or emergency landing, making the keyhole wasps a danger even in minimal conditions. Moreover, the keyhole wasp is inventive and highly mobile, building nests at Brisbane in on-ground servicing equipment as well as pitot probes, further contributing to their troublesome infestation.
Pitot probes are arguably the most crucial outside part of an aircraft for aviation safety. Aircrafts typically have two (but can have more)—these tubes are positioned one on each side of the pilot and co-pilot, allowing them to measure the outside airspeed accurately to safely judge take-off and landing speed, as well as a safe speed range to generate lift and to remain airborne. The blocking of these important tubes disarrays the readings and measurements required by the pilots for safe aviation. According to a study conducted at Brisbane published in public-access journal PLOS ONE, keyhole wasps there reportedly built their mud nests predominately in probes with a diameter range of 5-8 mm, favoring probes greater than 2.5 mm. Authors of this study state that the costs and consequences of not understanding this keyhole wasp threat “could be catastrophic”. Therefore, with consideration of our airports in Hawai’i, it’s important we recognize and understand this threat now.
The first instinct of many when confronted with an insect infestation is to simply use pesticide, or, if you think like me, a reliable can of roach spray kept under the kitchen sink. Unfortunately, pesticides and spraying treatments are proven harmful to humans and appear to not even be enough to curb keyhole wasps at Brisbane. Keyhole wasps are not the only wasps troubling Brisbane, they have as well warred with other species of wasps that build mud nests in and around terminal buildings and structures (not nearly as adeptly as the keyhole wasps)—routine pest management beginning in 2006 has drastically reduced the number of those wasps but has not dampened the keyhole wasp numbers, so, pest management is not a successful route.
Another tactic implemented at Brisbane are interception traps: screens extended between two objects to catch or snare flying insects and trap them in a container. On paper this tactic seems like it would be successful, but since being installed in 2018 the number of mud nests built by keyhole wasps in pitot probes have not lessened, and so, this is another failed attempt by Brisbane to curb the infestation. Because interception traps show none to minimal adverse effects to wildlife or noninvasive insects in an area, this appears to be the most safest method for both the environment and humans, so perhaps if Brisbane installed many, many more of these interception traps there could be some success with the assurance of safety.
Another measurement at Brisbane taken to maneuver around mud nests is a local policy adopted by numerous aircraft carriers: to cover pitot probes upon arrival to avoid keyhole wasps building nests in their aircrafts tubes. Not all carriers do this, and when performed, unfortunately, though it seems logical, is not always perfectly executed—in July 2018, a Malaysia Airlines Airbus A330-300 took off from Brisbane without first removing the covers on all three of the aircraft’s pitot probes. The flight crew detected an airspeed anomaly on takeoff and quickly re-landed with the help of air traffic control. In this case, the standard pre-flight walk-around inspection failed to recognize the pitot probes were still covered, but thankfully the flight crew recognized an issue right away. Although worst case scenario a plane crash could have resulted, this was only a case of a poor inspection. Brisbane determines that the covering of pitot probes upon arrival is the current most successful method of controlling keyhole wasps.
Brisbane has done its best with the bad cards its been dealt, but I believe that their best will not achieve a solid, lasting solution. Instead, I believe, the best solution for Brisbane’s keyhole wasp threat is simply the advancement of technology: senseAir developed by Ophir (and partnered with NASA). This new senseAir technology confronts the problems of the conventional air data sensors (pitot probes) that are prone to failures such as blockages from mud nests built by keyhole wasps. A single sensor could replace an aircrafts pitot probes, resulting in a higher-performing aircraft and reduced maintenance costs. Therefore, I believe that pest control, interception traps, and pitot covers aren’t what will solve the keyhole wasp threat, but rather, it will be technology and the outdatedness of pitot probes. When this advanced technology reaches us in Hawai’i, it is my hope that us and aircraft carriers will gladly incorporate it into our aircrafts so we’ll need not worry further for our aviation safety.
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