What eVTOL operators can learn from collision avoidance systems as airspace gets busier

Recent near misses have renewed attention on collision avoidance technology. But according to Ron Nye, President at Acron Aviation, such incidents should be seen as evidence that aviation’s safety systems are working as intended rather than failing.

He says, “Traffic Collision Avoidance System (TCAS) is designed as a final safeguard which sits in the background and coordinates with the TCAS unit of other aircraft. By the time an RA (Resolution Advisory) sounds, something earlier in the chain has already gone wrong. 

“It could be a misheard instruction or a controller juggling too much traffic.

“What these incidents tell us is that margins are getting thinner as traffic grows. The less often TCAS has to step in, the safer the system is.”

As air traffic continues to grow and air traffic control organisations face capacity pressures, collision avoidance systems provide an important independent layer of protection.

“TCAS gives every equipped aircraft an independent check that doesn’t depend on how busy the controller is. This is significant as air traffic is rising and many ATC organisations are short-staffed. Runway arrival rates are also fixed, so you cannot land more aircraft just because the demand goes up. When demand is high, aircraft end up in holding patterns and the workload lands on controllers and crew.”

What eVTOL operators can learn from TCAS

While collision avoidance systems have protected commercial aviation for decades, Nye believes the biggest lesson for emerging eVTOL operators is ensuring everyone in the airspace is working from the same picture.

He says the advanced air mobility sector has the advantage of being able to incorporate these capabilities into its operating model from day one, rather than retrofitting them later.

Why training and procedures are just as important as technology

Nye also highlights the importance of clear decision-making and training. “When TCAS was introduced, some crews weren’t sure whether to follow the RA or the controller. That confusion was a factor in the Überlingen mid-air collision over southern Germany in 2002. The rule now is simple – follow the RA. New operators should make that just as clear in their procedures and training.”

That principle becomes even more important as the industry moves towards remotely piloted and autonomous aircraft. 

“On a crewed aircraft, the pilot’s own safety is a powerful reason to follow an RA straight away. 

“Where eVTOLs fly with a remote pilot or none at all, operators can build that same reliability into the system itself, through automatic avoidance or clear remote-pilot procedures, so the right response happens consistently every time.”

Why traditional collision avoidance systems must adapt for eVTOL aircraft

As eVTOL operations become a reality, collision avoidance systems will need to account for aircraft that behave very differently from traditional airliners.

“An airliner holds its speed and heading for long stretches and collision avoidance logic was written around that. Helicopters, drones and eVTOLs can move left, right, up or down at short notice. Logic built for steady, level traffic has a harder time working out where they’ll be next. 

Regulators are already looking at the next generation of collision avoidance systems.

“The FAA has already defined a new generation of TCAS, ACAS X, with this mixed traffic in mind. It builds on the existing system, because a complete rewrite would mean retraining the whole industry. Then there are aircraft with no pilot on board. A drone can’t look out of the window, so the traffic picture has to be shared electronically between every aircraft and controller in that airspace. If everyone sees the same thing, the airspace can handle more traffic at the same level of safety. 

For Nye, one of the biggest challenges is that the success of collision avoidance systems is often invisible. 

“When these systems work, nothing happens. Two aircraft that stayed apart don’t make a story, so the public rarely hears about them.”

Instead, he argues that the industry should focus on interventions that prevent conflicts from developing in the first place.

“A better measure is how many conflicts never reach an RA, because a crew saw the traffic early and adjusted. That number is hard to count, which is part of the problem. When a near miss puts these systems in the news, I’d like the conversation to move on to earlier warnings for crews. That’s where the next safety gains will come from.”