The need for caution further heightened recently as new findings showed that pilots fail to catch sight of the flying gadgets by 70 per cent, even when they are in their airspace. And pilots almost never identify the machines if they are hovering motionless above the ground.
Operators of drones in Nigeria recently faulted regulatory restrictions by state agencies, describing it as the unnecessary bottleneck to the growth of such technology in the country.
The alleged restrictions, in the form of the lengthy registration procedure, licensing and clearance hurdles before multiple agencies, have allegedly fettered potential operators from deploying drones for commercial operations.
But a new U.S. investigation had uncovered a “real and present danger” to safety, and another reason both regulators and stakeholders must be careful.
Study co-author, Dr. Ryan Wallace, of Embry-Riddle Aeronautical University in the United States, said: “Dangerous close encounters between aircraft and drones are becoming an increasingly common problem.
“Statistics on pilot sightings of drones continue to increase year over year, and what is being reported by pilots is probably just the tip of the iceberg. The vast majority of the time, unmanned aircraft are not being seen by pilots.”
Two years ago a drone put 130 lives at risk after it nearly hit a passenger jet on its way into London Gatwick.
During experiments, 10 certificated skilled pilots did not notice a common type of quadcopter controlled by four rotors during 28 of 40 close encounters.
In other words, they saw the invading drone in about just 30 per cent of cases. And when it was not moving, the task became even harder.
A mere three out of 22 motionless machines, fewer than 14 per cent, were observed by the participants. The little successful detections happened at distances of just 213 to 2,324 feet.
Even in a best-case scenario, the maximum range would give a pilot roughly 21 seconds to avoid a collision.
Co-author, Dr. Matt Vance, an aviation expert at Oklahoma State University, said: “That might be enough time if the drone was hovering in one spot, but not nearly enough if it’s in flight, headed for the aircraft.”
He explained: “The situation is far more dangerous when both aircraft are moving. Our eyes are attuned to movement. When a drone is not moving, it becomes part of the background.”
The study published in the International Journal of Aviation, Aeronautics, and Aerospace (IJAAA), highlights the scale of the threat for the first time.
“An aircraft’s final approach for landing is an especially risky time because a drone “can catch you unaware and you have little time to react.”
Co author, Prof. Jon Loffi, also of Oklahoma State, added: “You don’t have the altitude to manoeuvre safely, and if an engine ingests a drone, which could bring the aircraft down.”
In a unique analysis, the U.S. team examined what happens as a pilot prepares to land and switches from instrument guided to visual flight. The participants were selected from a college flight training programme.
During the tests they carried out an approach to landing in a Cessna 172S while a DJI Phantom IV quadcopter drone flew a scripted series of manoeuvres along the same path. The pilots were told they may or may not encounter a drone.
In the U.S., there are currently more than 1.4 million registered drones, and likely many more unregistered ones. They continue to proliferate, Wallace said.
The number of drone users in the UK is unknown, but the Civil Aviation Authority has estimated 170,000 people will sign up to a proposed registration scheme.
Close calls between drones and commercial aircraft are on the rise. Last week a commercial crew on approach to Boston’s Logan International Airport reported a drone at about 3,500 feet – higher than U.S. Federal Aviation Administration (FAA) regulations allow. Just a week earlier after another crew spotted a drone after take-off from the same airport.
Wallace and colleagues said the FAA has made strides to secure control airspace from drone incursions. But “their efforts have been met with mixed results”.
There is currently no reliable method for tracking drone flights within the United States.
The researchers now plan to rig a drone with an electronic device that uses surveillance technology to track aircraft. They will assess whether it helps pilots pinpoint and avoid a collision.