How dangerous ARE bird strikes? The experts' guide to what happens when a flock hits a plane

• In 2013 the CAA had 1,535 reports of birds ending up in plane engines
• A bird-struck plane in March made an emergency landing in Beirut

By Becky Pemberton For Mailonline

Published: 05:11 EST, 15 July 2015 | Updated: 06:39 EST, 15 July 2015

Terrifying footage emerged in March this year of flames shooting out of the engine of a Lufthansa Airbus after it struck a flock of birds off the coast of Lebanon, forcing an emergency landing.

The incident is not uncommon and there were more than 1,535 reports of birds ending up in plane engines in 2013, according the Civil Aviation Authority. 

But just how dangerous are bird strikes? British Airline Pilots Association (BALPA) spokesperson Captain Steven Draper spoke to MailOnline to answer many of the most unsettling questions asked by passengers.

Bird strikes are not uncommon and there were more than 1,535 reports of birds ending up in plane engines in 2013, according the Civil Aviation Authority

Is it dangerous when a bird gets in the engine? 

'Strikes are occasionally dangerous,' author and pilot Patrick Smith wrote in Cockpit Confidential.

'This is especially true when engines are involved, as we saw in 2009 when US Airways flight 1549 glided into the Hudson River after colliding with a flock of Canada geese.'

In this incident Captain Sullenberger courageously landed an A320 in the Hudson River after the plane lost thrust in both engines following the bird strike, which occurred moments after take-off. 

'Modern turbofans are resilient, but they don't take kindly to the ingestion of foreign objects, particularly those slamming into their rotating blades at high speeds,' said Smith. 

'Birds don't clog an engine but can bend or fracture the internal blades, causing power loss.'

This scenario was seen in the Lufthansa Airbus A321 incident above Lebanon, and the plane, carrying 144 passengers, lost power in one of its two engines and was forced to turn around and make an emergency landing in Beirut. 

A collision with a flock of large Canadian Geese led to the heroic Captain Sullenberger landing an A320 in the Hudson River in 2009

The pilot of the aircraft reported a 'double bird strike' to air traffic controllers moments after taking off and said he had lost thrust in both engines

Experts said landing the Airbus on the Hudson took supreme skill

Footage from miraculous Flight 1549 landing on Hudson River

What happens when the bird hits the engine? 

Smith stated that the heavier the bird, the greater the potential for harm. 

'Flying at 250 knots - in the United States, that's the maximum allowable speed below 10,000 feet, where most birds are found - hitting an average-sized goose will subject a plane to an impact force of over 50,000 pounds. 

'Even small birds pose a threat if struck en masse. In 1960, an Eastern Airlines turboprop went down in Boston after an encounter with a flock of starlings.'

What happens to the bird?

Unsurprisingly a sad fate usually awaits any bird who find themselves about to hit the plane engine. 

BALPA Spokesperson Captain Steven Draper said: 'The energy within the engine generally means the bird will disintegrate. 

'There can, in a serious incident be extensive damage to the engine. 

'After a bird strike, or possible bird strike, the engine will be checked for evidence of bird debris, and if debris is found a series of further checks will be carried out.'

An Airbus A321 was hit by birds immediately after taking off from Beirut’s international airport en route to Frankfurt in March of this year

The plane was carrying 144 passengers when it lost power in one of its two engines and was forced to turn around and make an emergency landing in Beirut

Flames shoot out of engine after plane strikes birds mid flight

At what altitude are aircraft safe from birds?

Captain Steven Draper said: 'The vast majority of bird strike incidents take place during take-off and landing phases - so fairly near the ground, although birds have been occasionally hit at higher altitudes.'

On the whole the majority of air strikes occur below 3,000 feet above ground, although there have been incidents occurring at higher altitudes. 

This is simply due to the face that above 10,000 feet there are a reduced number of birds, but this hasn't stopped it happening at 30,000 feet and higher. 

How do engineers try to prevent it from happening?

Smith wrote that aircraft components are built to tolerate such impacts.

'You can see web videos of bird carcasses being fired from a sort of chicken-cannon to test the resistance of windshields, intakes, and so forth.

'I've personally experienced several strikes, and the result was, at worst, a minor dent or crease.'

There have been several 'bird scaring' tactics employed for discouraging birds around airports

Is there any way to reduce the number of bird strikes that occur?

Large flocking birds, such as Canada Geese have become a major problems as they pose more of a significant risk of collision. 

They often fly in dense formations and their global population is rising rapidly.

'The best idea is to keep birds and aircraft apart where possible,' said Captain Draper. 

'Measures to control their numbers in certain locations have been implemented within the USA.'

In addition to this construction of new airports away from bird migration or roosting habitats could help reduce the chance of an aircraft and bird coming together.

There have been several 'bird scaring' tactics employed for discouraging birds around airports. 

Many resort to playing distress calls and firing flares - and some have even tried controlled use of birds of prey. 

In some places disrupting breeding cycles, keeping airport grass at a length to discourage birds and ensuring buildings have anti roosting precautions in place can also help.

'There are also ways of making the aeroplane bird visible,' said Captain Draper. 

'Making sure the lights are on and flying at a speed that gives birds a chance to move out of the way and reduce bird damage if a collision occurs can help. 

'The RJ100 I flew for three years was limited to 250kts below 10,000ft in order to prevent critical damage to the wings leading edge in the event of a bird strike. 

'Windows can be constructed from multiple layers and heated, the heating process increases the strength of the lamination, therefore increasing resistance to damage from bird impact.'

It has not been proved that the spirals inside plane engines prevent birds from flying into the engine

Are the spiral marks in the centre of the engines to keep birds away? 

Although some say the spiral marks in the middle of plane engines are to ward off birds, this is not necessarily the case.  

'There is no requirement for engines to have spiral marks and primarily these are to assist ground engineers,' said Captain Draper. 

'There is some suggestion that birds might see the spinning spiral as opposed to a large black hole, but there is no firm evidence to support this.'

Are there new designs to tackle the issue?

Captain Draper said: 'Technology with the use of anti-bird lighting on aeroplanes, and avian radar to enable airports to suspend take offs and landings when in conflict with flocks of birds are being investigated.'

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