What's the point of scrambling a fighter jet – and would one ever shoot down a passenger plane?

There is something incredibly jarring about seeing a commercial aircraft, packed to the rafters with sunseekers, flying alongside a fighter jet.

The two should comfortably go about their business, never needing to interact, so when they do it is somewhat concerning. Such alarm was felt this week when two RAF Typhoon jets were scrambled to intercept a Ryanair passenger plane after a suspected bomb hoax.

The aircraft - carrying passengers from Kaunas in Lithuania - was met by the military jets in the skies off the coast of East Anglia, before being escorted to London Stansted, one of the UK’s designated emergency airports, rather than the intended destination of Luton.

The dramatic scenario came to a peaceful conclusion and all was well - but what might the RAF jets have done had things taken a turn for the worse?

10 airports where emergency landings happen all the time

What is scrambling?

With origins dating back to the Battle of Britain, scrambling - known today in military terms as Quick Reaction Alert (QRA) - is when RAF pilots respond to an alarm and are able to take to the air in fuelled and armed fighter jets in a matter of minutes.

The RAF see it as a routine part of its defence role to protect UK airspace. Aircraft at bases around the UK, and even in the Falkland Islands, under the guidance of Air Battlespace Controllers at RAF Boulmer in Northumberland and RAF Scampton in Lincolnshire, are ready to take off in minutes.

When does it happen?

There are a number of reasons RAF jets are called upon to meet other aircraft above Britain, though it is always with the goal of protecting our airspace.

The RAF said, among other reasons, aircraft are “launched to intercept unidentified aircraft because the aircraft cannot be identified, i.e the aircraft is not talking to civilian or military Air Traffic Control, has not filed a flight plan and/or is not transmitting a recognisable secondary surveillance radar code”.

This includes light and commercial aircraft, as well as military jets of other nations. In 2015 RAF Typhoons were scrambled to meet two Russian military aircraft “disrupting” civil aviation near UK airspace.

In March a private plane from Bucharest was escorted into Birmingham Airport by RAF fighter jets after it experienced communication difficulties. The aircraft was met by two Typhoon jets scrambled from RAF Coningsby, and a Voyager aircraft, from Brize Norton.

In 2014, an RAF Typhoon jet escorted a Qatar Airways aircraft into Manchester Airport after a pilot requested assistance when a passenger on board made a bomb threat.

So, a commercial pilot can request help, or, if an aircraft fails to communicate repeatedly with Air Traffic Control or strays of course, fighter jets might be scrambled as a precaution. 

secrets of air travel

What are the fighter jets permitted to do?

In a worst case scenario, shoot down another plane. A 2015 documentary on RAF’s Quick Reaction Alerts showed a fighter jet pilot telling the pilot of a commercial jet in a training exercise that if he did not respond to repeated attempts to communicate the aircraft would be shot down.

Every scrambled jet is armed and ready if need be to fire on another aircraft. Such a decision would have to be taken at the highest political level, however.

Of course, the first job of the fighter pilot would be more sedate, and would usually be to establish contact and continue to flank the target aircraft. In a more serious situation, jets might be deployed to force an aircraft to take a certain route. London Stansted and Manchester Airport are the UK’s two designated emergency airports and the most likely target airports if the RAFs needed to lead a plane to land.

How often does it happen?

The RAF says that fighter aircraft are available at each base all day every day allowing a rapid response to any possible incident or threat, but there have only been five such scramblings this year - two against Russian military aircraft and three for other reasons.

The year with the most QRAs was 2007, when there 24 incidents that required military scrambling. Of those, 19 were for Russian aircraft. Last year the number was 12, with five for the Russians.

Last year defence secretary Michael Fallon said Russian fighter jets that were unresponsive as they approached the UK amounted to an “act of aggression”.