When flying over Indian skies, it's a bird, it's a plane, it's a bane

Birds and sundry animals pose a permanent safety hazard at Indian airports built near densely populated areas

On June 19, a SpiceJet plane carrying 191 people that had just taken off from the Patna airport had sparks and smoke coming out of one of its engines below the left wing. Captain Monica Khanna took the plane back to Patna airport. An inspection after landing showed a bird had gone inside Engine 1 and damaged three of its fan blades. Khanna’s feat and photo spread far and wide on social media.

The same day, an IndiGo plane returned to the Guwahati airport soon after take-off because of a suspected bird hit. Six days later, last Sunday, a helicopter carrying Uttar Pradesh Chief Minister Yogi Adityanath made an emergency landing in Varanasi after, well, a bird hit. All of a sudden, bird hits on aircraft began to fly as a topic of discussion and curiosity.

Bird hits are not uncommon in Indian skies; in 2021, aeroplanes suffered an average of four bird hits a day. And birds alone are not to blame. Last year, a pack of 25-30 golden jackals were reported to be roaming around the runway at the Chipi airport in Sindhudurg, Maharashtra. There have been reports of sundry other animals — among them cows, dogs, nilgai (blue bull) and even dead foxes — turning up at airports.

This is no surprise, given that many of India’s airports are situated close to densely populated areas and have open drains or garbage dumps in the vicinity. The Patna airport, which has an open abattoir close to it, has a group of employees dedicated to driving birds away. Last year, airport officials in Ahmedabad made an employee dress and pose as a bear to keep monkeys away.

But bird hits are no monkey business. Planes reporting bird hits are given priority to land at airports and the engines are immediately taken off for inspection. Repairing them is a costly affair. Boeing, the aircraft manufacturer, says an engine, usually priced around $10 million, can incur repair costs of $1.6 million after being hit by a bird or other debris. Just replacing a set of fan blades can cost $25,000. Damage to critical components that are beyond repair mean new engines must be purchased.

Yet, the process of identifying and dealing with a bird hit relies a lot on natural human abilities and observations — say, spotting smoke or sparks, or getting the smell of burning flesh — rather than a system based on technology or instruments. In fact, such hits can often go unnoticed. But, when one does get noticed, split-second decisions have to be taken to ensure the safety of everyone on board.

“The first thing you notice is a flock of birds around the plane. Then there is thud and you realise one or more has been ingested by the engine. Usually, there is no abnormal engine activity and we continue the flight. But sometimes an unusual engine vibration is palpable. Large birds (such as seagulls and geese) cause more damage to the blades and may even start an engine fire,” said a pilot with a private airline.

The United States aviation regulator, the Federal Aviation Administration, highlights in its periodic training that “most bird encounters do not affect the safe outcome of a flight. In more than half of the bird ingestions into engines, the flight crew is not even aware that the ingestion took place”.

At times, only when the bird hit is unusually big, pilots see an engine surge: its compressor, which funnels in high-pressure air, stalls as the ingested object disrupts the airflow to burn fuel. This is reflected in deviations on instruments, such as the engine pressure ratio (EPR) and the exhaust gas temperature panels. The EPR indicates the thrust produced by the engine and unusual readings point to a loss of power that calls for action by the pilots to stabilise the aircraft.

The Directorate General of Civil Aviation (DGCA), India’s aviation regulator, has put bird or animal strike reporting guidelines in place. But it has acknowledged that such events are an integral hazard of aviation and need to be dealt with accordingly. In 2018, it issued an advisory that sometimes the best course of action is inaction.

“Before considering the use of an active method to disperse or deter wildlife on the aerodrome, consideration should be given to the fact that doing nothing may in some cases be a better choice than chasing birds away and losing control,” said the advisory.

Analysts say it was the SpiceJet incident in 2014, when the plane hit a blue bull on the runway, which roused the regulator. “Before that, the DGCA was pretty lax about wildlife threats at aerodromes. According to the DGCA, they are doing better at preventing bird hits than the targets they have set for themselves. But it is also about all the hits that are going unreported,” said Captain Amit Singh of Safety Matters Foundation.

The DGCA also advises increasing human presence at aerodromes, noise-making devices and use of flare guns to ward off birds. And, when all else fails, you can always get someone to dress up as a bear.

Hit show

• In 2021, aeroplanes suffered an average of four bird hits a day
• Sundry other animals — cows, dogs, nilgai (blue bull), even dead foxes — also pose a threat
• Boeing says a $10-million engine can incur repair costs of $1.6 million after being hit by a bird or other debris
• The process of identifying and dealing with a bird hit relies mostly on natural human observations rather than technology
• US Federal Aviation Administration says most bird encounters do not affect the safe outcome of a flight
• DGCA has bird or animal strike reporting guidelines in place
• In 2018, it issued an advisory that sometimes the best course of action is inaction
• DGCA also advises increasing human presence at aerodromes, noise-making devices and use of flare guns to ward off birds