Pilots dislike the term “near-miss”.
It’s a phrase that conjures in laymen minds two planes, inches apart, averting catastrophic disaster by a matter of seconds. Perhaps one aircraft’s wing scrapes the undercarriage of another, sending sparks flying.
Enter “near miss” into a search engine and the results in the news section would have you believe that planes are regularly dodging each other in a sky filled with chaos. The reality is much drier.
“We don’t use the term near-miss,” explains Martin Rolfe, chief executive officer of NATS, in charge of air traffic control in the UK.
“We call it a loss of separation. Broadly speaking, that is when two aircraft have gotten closer together than they should have done. And that doesn’t mean it is hugely dangerous.”
Loss of separation is certainly less sexy than near-miss – but what should the separation be?
How far apart should planes fly?
The separation protocols are governed by the International Civil Aviation Organisation (ICAO) and respective national authorities, such as the UK’s Civil Aviation Authority (CAA) and the Federal Aviation Administration (FAA) in the US.
Aircraft should be kept 1,000 feet or 300 metres apart vertically. Horizontally, if aircraft are following the same path – or track – they should be 15 nautical miles apart. Under other circumstances, planes should be at least five nautical miles apart, a distance allowed to drop to three when the aircraft enters the jurisdiction of an airport’s tower controller; on final approaches into airports (within 10 nautical miles) this is allowed to drop to 2.5.
How dangerous is a loss of separation?
“You can imagine that two aircraft are landing, and the one behind is catching it up,” says Rolfe. “While that means it is legally closer than it should be, the other aircraft can land and already turn off the runway before the second plane has even begun to land.”
He explains that advances in GPS technology means that air traffic control can keep much closer tabs on aircraft – as well as allowing them to keep tabs on themselves – and that each plane is now equipped with Traffic Collision Avoidance Systems (TCAS).
TCAS allows the flightdeck to monitor the airspace around them to ensure there is no chance of a collision. Alarms sound if any other planes enter their immediate airspace.
A typical system would alert pilots to “traffic” if within 35 and 48 seconds of a collision and urge “resolution” if within 20 to 38 seconds.
“The number of serious losses of separation is incredibly small,” says Rolfe. “It is unusual in the UK’s airspace – the most serious being a Category A – and I don’t think we’ve had one in five years.
“The guys do an amazing job of keeping the planes apart here, while in other parts of the world they might be more frequent. But generally speaking the risk to flying from any kind of air traffic incident is incredibly low.
“You are at far more risk getting into your car in the morning than you are flying into UK airspace.”
For the avoidance of doubt, any pilot involved in a potential head-on collision is trained to turn right. Everyone turns right.
Have planes not always had collision avoidance software?
Having a TCAS on board was only made compulsory by law at the end of the Nineties, first in the US in 1993, followed by India in 1998, Europe, Australia and Hong Kong in 2000 and finally Argentina in 2014.
A number of incidents – be they near-miss or actual mid-air collisions – are cited as the impetus for legislating on the systems.
One of the earliest such incidents was the Grand Canyon mid-air collision in 1956, when a United Douglas DC-7 collided with a Trans World Airlines Lockheed L-1049 over the National Park, killing all 128 onboard. It was the first commercial air crash to claim more than 100 lives and led to clamour for sweeping changes in the way flights are controlled in the US. Four years later, another United Douglas collided with another TWA Lockheed over New York’s LaGuardia airport, killing 128 people on board and six on the ground.
After continued pressure for action, the Federal Aviation Act of 1958 created the Federal Aviation Agency, later renamed as the Federal Aviation Administration, to manage the skies. It still exists today.
Do near-misses still happen today?
Yes. Most recently, a “loss of separation” saw an Air Canada aircraft nearly land on a crowded taxiway.
A list compiled by Skybrary, an aviation website, shows the number of loss of separations that have happened around the world in recent years, though most are not serious.
The Aviation Herald, too, records such incidents. The last one it mentions took place near Barcelona in July last year. The website says a Vueling Airbus A320 and Blue Panorama Boeing 767 came within 100 feet verically and 1.5 nautical miles of each other.
A report in 2014 found that there were some 150 losses of separation in European airspace for every one million flights. In 2016 there were some 10.1 million flights, a new record.
Mesmerising video of the UK’s daily air traffic
What about flying in formation?
Why do the Red Arrows get away with it? They of course get special dispensation for their displays.
ICAO rules state: “Aircraft shall not be flown in formation except by pre-arrangement among the pilots-in-command of the aircraft taking part in the flight and in accordance with the conditions prescribed by the appropriate authorities.”
It adds that “an aircraft shall not be operated in such proximity to other aircraft as to create a collision hazard”.
Should I be worried?
“There are three things you should know,” says BA pilot Steve Allright. “Firstly Air Traffic Controllers around the world are carefully selected, highly trained and rigorously tested and licensed. Their job is to create a protective bubble around the aircraft which increases in size as the aircraft climbs and gets faster.
“Secondly, pilots are selected and trained to have a high level of situational awareness and are the most highly regulated professionals in any industry. Thirdly, all commercial aircraft are fitted with electronic equipment which allows them to talk to each other, which removes the human element and provides warning and guidance of any proximity to another aircraft. We practice using this equipment in the simulator.”