SINGAPORE - A runway incursion has been singled out as a probable cause of the fiery collision between a Japan Airlines jet and a coast guard plane at a Tokyo airport on Jan 2.

Such incidents have been on the rise in some parts of the world.

A runway incursion is the “incorrect presence” of an aircraft, vehicle or person on a runway designated for landing and take-off, as defined by the International Civil Aviation Organisation.

Between January and October 2023, the United States Federal Aviation Administration (FAA) identified 19 serious runway incursions in the country, all of which were classified as near-misses.

This is the highest number of runway incursions recorded in any given year in the US since 2016.

Citing the inexperience of airline pilots, staffing problems and outdated technology as reasons for such accidents, the FAA also said the US has about 1,000 fewer certified air traffic controllers than in 2013.

According to a 2022 safety report published by international aviation safety organisation Flight Safety Foundation, runway collisions were behind two of the 115 commercial aircraft accidents around the globe that year.

The cause of the Jan 2 collision at Tokyo’s Haneda Airport is still being investigated.

The Straits Times looks at major runway incursions that have happened in the past, and mitigating measures airports and airlines have set in motion.

Q: What are some major runway incursions that have occurred in history?

A: One notable example of an incursion is the 1977 collision between two Boeing 747 jumbo jets, operated by KLM and Pan American World Airways, on a runway at then Los Rodeos Airport (now Tenerife North-Ciudad de La Laguna Airport) in Spain. It killed 583 people – the largest number of fatalities in an aviation accident to date.

Another collision happened in 1972 when a North Central Airlines McDonnell Douglas DC-9-31 aircraft crashed into a Delta Air Lines Convair CV-880 plane on a runway at Chicago’s O’Hare International Airport, due to the failure of air traffic control. The incident killed 10 and injured 17.

Fatal runway collisions are, however, rare.

Mr Michael Daniel, managing director of consultancy Aviation Insight and a member of the International Society of Air Safety Investigators, noted that runway incursions are the third most common cause of aviation accidents, after controlled flight into terrain and uncontrolled flight into terrain.

Controlled flight into terrain refers to the unintentional flying of an aircraft into the ground, water or a mountain under the pilot’s control due to poor weather and pilot error. Meanwhile, uncontrolled flight into terrain is similar to controlled flight into terrain, except the pilot loses control because of mechanical failure or uncontrolled situations such as a fire on board, added Mr Daniel.

Q: Have runway incursions happened in Singapore?

A: Yes. From 2000 to 2023, at least 12 runway incursions have happened at Changi and Seletar airports, according to publicly available air safety investigation reports by Singapore’s Transport Safety Investigation Bureau.

Some involved ground vehicles, such as crane or maintenance vehicles, entering runways without receiving clearance from air traffic control. In other instances, some aircraft entered runways without obtaining permission.

In November 2020, a Tri-MG Intra Asia Boeing B737-300 cargo plane entered a runway at Changi Airport without air traffic clearance. Another aircraft was approaching, and the cargo plane managed to vacate the runway in time on instructions from air traffic control.

In February 2022, a Eurocopter EC135P2 helicopter from PT Ekspres Transportasi Antarbenua entered the runway at Seletar Airport before clearance was given. There was no other aircraft approaching, or on, the runway then.

Mr Daniel cited a variety of contributing factors for runway incursions. These could include lapses in communication on the part of air traffic controllers, a lack of pilot situational awareness or technical failures in airports’ runway warning systems.

Q: What are some systems in place to prevent runway incursions?

A: Autonomous runway incursion warning systems are used in many airports to automatically detect the presence of an aircraft or vehicle on an active runway and warn the flight crew or vehicle operator, according to aviation safety information repository Skybrary.

Such systems will communicate relevant runway information to aircraft via warning lights located at the runway take-off threshold and entrances, to alert pilots that it is unsafe to enter a runway or to begin taking off from the runway, noted Skybrary.

In Singapore, there are microwave barrier detectors on each side of the runway holding positions at Changi Airport to detect unauthorised entry of aircraft or vehicles into runways.

Runway holding positions are designated positions where taxiing aircraft and vehicles must stop completely and seek clearance from air traffic control before proceeding onto the runway.

These detectors will trigger an alert to air traffic control once unauthorised entry is discovered, according to airport operator Changi Airport Group’s airside driving theory handbook.

Q: Besides the use of these technologies, what other checks are done to minimise runway incursions?

A: Despite the availability of these technologies, much of the onus lies on pilots to ascertain if there are aircraft or vehicles on the runways.

A former pilot of more than 30 years for a Singapore-based airline, who spoke to ST on condition of anonymity, noted that airlines have standard operating procedures that require pilots to conduct visual checks of the runway and check “the runway shown on the navigation display”.

“We are also trained to look at the approach end of the runway to ensure there are no approaching aircraft that will affect our take-off,” he added.

At the same time, the former pilot said the airport authorities use surface movement radars to monitor aircraft movements on the runways.

Q: How can governments, airports and airlines better prevent runway incursions?

A: Mr Greg Waldron, the Singapore-based Asia managing editor of industry publication FlightGlobal, emphasised the importance of the publication of detailed and open investigation reports of aviation incidents.

“Governments have an important role to play, as they can take measures to mitigate the issues by analysing reasons behind past incidents, and to work these learnings into their workflow,” he added.

Mr Waldron said these accident reports are essential in informing governments, airports and airlines about the changes they should make to their training, operations and procedures.

Mr Daniel of Aviation Insight said Asia-Pacific aviation regulators should come together to host more safety seminars so they can learn from past accident investigations and apply the recommended mitigating measures to their operations.