Why aircraft, birds don’t flock together

Uganda Airlines planes at Entebbe airport. In May 2021, a Uganda Airlines Bombardier CRJ-900 was temporarily withdrawn from service after suffering a bird strike to its left-hand engine as it took off from Entebbe to Juba. PHOTO/ FILE

What you need to know:

  • The hazard of birds to the aviation industry is a million-dollar burden. An airline can lose up to $10 million (Shs36.8b) in replacement of a single aircraft engine after destruction by birds.

It was 17 years ago that Kenya’s The Standard newspaper ran an article with a consummate headline. “Birds in flight are beautiful… but only from the ground,” it said.
From inside the cockpit of the Turkish Airlines Airbus 330 on Tuesday, the flight captain and assistant—whose identities authorities at Entebbe International Airport declined to reveal—probably saw the barn swallows but it wasn’t that fanciful sight bird watchers pay for.
The flight 606, with 281 passengers and crew on board, had just taken off from Entebbe for Istanbul, Turkey, at 7.30am when the swallows struck one of its engines.

The passerine bird weighs just about a few feathers. But when it comes to aircraft-bird collisions, size doesn’t always matter.
“There have been instances where birds the size of robins bring a plane down,” John Ostrom, who chaired the US Bird Strike Committee—formed in 1991 to analyse bird strike data and advise the aviation industry, once said.
The 1.8-tonne Airbus felt the impact of the 20g swallows and indeed had to come back down.
Collision between a bird and an aircraft in flight or on a takeoff or landing roll happens almost daily around the world.
For instance, as the Turkish airliner was flying around Kampala for nearly one-and-a-half hours to burn fuel, the crew of a Southwest Airlines Boeing 737-700 was forced to stop a climb at 4,000ft in Sacramento, California, following a bird strike.

While the THY 606 in Entebbe passed the airworthy checks after the emergency landing, the WN-1096 in Sacramento was grounded.
Including the Entebbe incident, Turkish Airlines has experienced at least a dozen bird strikes since 2018 as per Aero Inside records.
Mr Oscar Ssemawere, the chief executive of Entebbe Airways, says birds are attracted to airports.
“Many airports are located along migrating routes used by birds,” he says.
But while most bird strikes do not cause major damage or even get registered as turbulence, American airport wildlife hazard experts and scientists Richard Dolbeer, Phil Shaw and Jeff McKee, in a 2019 report, said at least 532 people have been killed and 614 military and civil aircraft destroyed since 1912.
Avisure, an international aviation risk consultancy firm that works to mitigate bird strikes, puts the fatalities from bird strikes at 342 for civilians and 193 for military.
 
Huge cost
The US Federal Aviation Administration’s website on Airport Wildlife Mitigation says bird strikes cause more than $300 million (Shs1.2 trillion) of damage each year. Between 1988 and 2017, some 263 civilian aircraft were either destroyed or damaged beyond repair due to wildlife strikes.
Sunday Monitor contacted industry regulators in the region for data on bird strike. Information available online however indicates that in Kenya, bird strike data involving Kenya Airways aircrafts at Moi International Airport in Mombasa, Jomo Kenyatta International Airport in Nairobi, and Kisumu International Airport showed 224 incidents in just two years leading up to 2001.

Nairobi had the highest number of strikes (90), followed by Kisumu (88) and Mombasa (46).
In 2002, Kenya Airways was reported to have spent KShs225 million (Shs6.7 billion) in repairs owing to bird strikes. 
The airline, which has in the last decade been enduring more financial than air turbulence, suffered bird strikes twice in 2005 at Moi airport, in August 2003 at Kisumu airport, and also coughed up KShs30 million (about Shs900 million) to repair an engine damaged by a crow in 2002. 

In Rwanda, RwandAir cancelled flights to Nairobi after a marabou stock hit one of its planes in April 2006. Then RwandAir boss Manzi Kayihura told State-run The New Times that the bird-scare was the third in six months.
In February 2010, RwandAir’s new Bombardier CRJ 200 was forced into a safe landing by birds. It would remain grounded for months.
In October 2018, RwandAir was forced to cancel its WB202 flight from Kigali to Nairobi after a bird strike.
Until last Tuesday at Entebbe, the most high-profile incident was recorded in October 2010. A KLM Airbus A330-200 departing Entebbe for Amsterdam, Netherlands, ingested a bird into the right hand engine on lift-off.
Passengers reported hearing a loud bang and must have smelt the aroma of a roasted chicken waft in the cabin as the grey crowned crane (Crested Crane) was eaten up by the CF6 engine.

The aircraft safely returned to Entebbe shortly afterwards and was grounded.
In May 2021, Uganda Airlines Bombardier CRJ-900, registration 5X-KDP, was temporarily withdrawn from service after suffering a bird strike to its left-hand engine as it took off from Entebbe to Juba.
The incident resulted in damage to the engine inlet cowl. The national carrier would incur at least $300,000 (Shs1.1 billion) on top of related costs in re-certification prior to return to service (charges on prolonged grounding of aircraft). 
In their study on the ecological effects of aviation, Irish zoologist and ecologists Tom Kelly and John Allan used the noisier Boeing 707, 727 and 737 series 200 compared to the Boeing 737 series 300-800 and the Airbus series A300 to A340 to show the repertoire of avoidance behaviour of rook birds to the different aircraft.

“The results showed that significantly fewer rooks responded to the A300 to A340 than to the B737-200, a distinctly noisier aircraft. This suggests that noise may be an important cue for rooks,” they concluded.
But Mr Ssemawere says that cannot be, stressing that all aircraft suffer bird strikes.
“A bird strike is a bird strike,” added Captain Stephen Wegoye, a retired pilot who has flown almost all Uganda’s presidents.
“It does not choose which type of aircraft it is. It is like an accident. It doesn’t matter what type of vehicle one is driving. If it is to happen, it will happen.”
 
What happens during a bird strike?

The first powered flight by the Wright Brothers occurred in December 1903. On September 7, 1905, the first reported bird strike, as recorded by Oliver Wright in his diary, occurred when his aircraft hit a bird as he flew over a cornfield in Ohio, US.
As birds fly at lower altitudes, most plane collisions with them occur during a takeoff, initial ascent approach, or landing.
Bird strikes mostly damage the forward-facing areas of the aircraft (the windscreen, nose cone, and engines). Bird strikes to the nose cone rarely lead to an emergency.
And while windscreen damage can be more serious, as a shattered windscreen can mean loss of cabin pressure, and would usually necessitate a diversion to a nearby airport, the biggest risk to flight safety is when a bird gets caught in the engine of an aircraft.
This can cause the engine to fail. As most airplanes are capable of flying on one engine, this would normally mean a safe landing at the nearest airport with little or no fuss at all.

However, there are rare occurrences where birds have been ingested by both engines, causing a dual engine failure. There is a classic example. On January 15, 2009, an Airbus A320 en route to Charlotte from New York City’s LaGuardia Airport flew into a flock of birds shortly after takeoff. The bird strikes affected both engines.
With no power and no suitable airport for an emergency landing, pilots Chesley Sullenberger and Jeffrey Skiles decided to glide the aircraft into the Hudson River where all 155 people on board, including five crew members, were rescued by boats.
Only a handful of people were injured in the “Miracle on the Hudson” flight—considered the most successful ditching in aviation history. The incident was later made into the 2016 film, “Sully” (co-starring Tom Hanks as Sullenberger).
 
Sweeping airports

The hazard of birds to the aviation industry is a million-dollar burden even for airports with no bird habitats around it. An airline can lose up to $10 million in replacement of a single aircraft engine after destruction by birds.
“The operator picks the bill since I doubt there would be many insurers willing to cover [such] damage. Once they take reasonable control measures, airports adopt a policy akin to parking at your own risk,” says Mr Michael Wakabi, a veteran aviation journalist.
While advances in aeronautic engineering have seen modern engines developed with fan blades that repulse birds, most efforts are geared at controlling the animals from the airport.
Entebbe was gazetted as a wildlife sanctuary in 1951 and that renders it a battleground for the two birds.

“Uganda is endowed with over 1,060 different bird species. Twice a year, Entebbe receives visiting species as it is a migratory path of birds from Europe,” says Mr Vianney Luggya, the spokesperson of the Uganda Civil Aviation Authority (UCAA).
Some of the bird species at Entebbe include the black kite, barn swallow, crested cranes, egret, gulls and terns.
Like many airports, Entebbe has a bird hazard control unit charged with engaging in running battles with the birds before an aircraft takes off or lands. The unit has a team of 27 staff headed by a zoologist.
“They have over the years done a tremendous job to keep bird strike incidents at the bare minimum,” Mr Luggya says.

The Bird Hazard Control Unit has to monitor wildlife attractants such as water ponds and sweep the runways before landings or takeoffs.
“The dispersal involves use of pyrotechnics bird scare pistols with bird scare cartridges not meant to kill but scare away, foot patrolling which provides the best dispersal method using catapults and clappers, use of laser bird repellent system, and distress calls,” Mr Luggya says.
While a bird can force an Airbus to back off the airspace, there are no records to suggest that any of the feathered animals ever survive a collision in the skies. And this has attracted quite some teeth-grinding from ecologists.
For fliers, bird strikes rarely mean more than a turbulence that triggers emergency landing after takeoff or an extra-guided landing. But they can scare from the airspace.


Bird strikes
Bird strikes mostly damage the forward-facing areas of the aircraft (the windscreen, nose cone, and engines). Bird strikes to the nose cone rarely lead to an emergency.
And while windscreen damage can be more serious, as a shattered windscreen can mean loss of cabin pressure, and would usually necessitate a diversion to a nearby airport, the biggest risk to flight safety is when a bird gets caught in the engine of an aircraft.
This can cause the engine to fail. As most airplanes are capable of flying on one engine, this would normally mean a safe landing at the nearest airport with little or no fuss at all.
However, there are rare occurrences where birds have been ingested by both engines, causing a dual engine failure. 
 

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