Understanding bird strikes and aviation safety

When are aircraft more prone to bird strikes? How is the DGCA planning to prevent such incidents?

The story so far: On June 19, a SpiceJet Boeing 737-800 on the Patna-Delhi sector (SG723) with 185 passengers was in the climbout phase (the period immediately after take-off during which the aircraft climbs to a predetermined cruising altitude) when it suffered a bird hit in its left engine. Ensuing visuals showed flame streaks. The engine was shut down and the flight returned to Patna about 20 minutes later. The same day, an Indigo Airbus A320N (6E-6394, Guwahati-Delhi) was taking off when it experienced a bird hit in the left engine. The aircraft returned to Guwahati about 15 minutes after its departure. In both incidents, some of the engine blades were damaged or had fractures. India’s civil aviation regulatory body, the Directorate General of Civil Aviation (DGCA), has ordered an inquiry. Further, in a directive to all airport operators, it has asked all airports to “review their wildlife hazard management plans” for “within and outside the airfield”. Being the monsoon season with heightened wildlife activity, this would include grass trimming, runway inspections, garbage disposal in operational areas and ensuring water drainage.

The International Civil Aviation Organization (ICAO) has been collecting bird strike data since 1965, but it was in 1979 that it requested member states to begin reporting bird strikes to aircraft into a data entry and retrieval system. The ICAO Bird Strike Information System (developed with the help of experts) has been in operation since 1980. An analysis of 62,416 verified records showed that most hits were in or near airports during the take-off and approach phases of flight. About 60% occurred at or below 30 metres or around 100 feet, according to a paper on the ICAO bird strike information system. Another paper, “Bird strikes at commercial airports explained by citizen science and weather radar data”, says that in 2017, “over 14,000 bird strikes were reported only in the United States; for that year alone, the cost was $142 million”. A third paper, “The costs of bird strikes and bird strike prevention”, by Allan J.R., says that, globally, “the annual costs of bird strikes are an estimated $1.2 billion”. Scientists from the Cornell Lab of Ornithology and partners say that information on bird movements throughout the year can help avoid aircraft damage and risk to passengers. In 2018, the Federal Aviation Administration data on civilian flights in the U.S. recorded 14,661 collisions with wildlife, which is over 40 cases a day.

A report says that in India in 2021, DGCA data has recorded over 1,400 suspected and confirmed wildlife incidents (for 20.5 lakh aircraft movements), up from nearly 840 cases in 2016 (for 22.9 lakh aircraft movements). Most of the incidents were reported from Delhi and Mumbai airports.

In India’s National Aviation Safety Plan (2018-2022), which is in line with ICAO’s Global Aviation Safety Plan, the DGCA has said that one of the key safety priorities (under the Safety Enhancement Initiatives of the Regional Aviation Safety Plan – Asia Pacific) is looking at “wildlife and bird strikes”. It says the audits suggested by the National Bird Control Committee (NBCC) are being followed. Under Safety Performance Indicators of “Number of reported bird strikes at all Indian airports per 10,000 movements”, it lists a Safety Performance Target of 4.26 for the year 2022.

A senior commander who flies the Airbus A320 aircraft told The Hindu that bird hits are a risk that flight crew have to be constantly ready for, especially during the take-off phase as the aircraft is fully loaded and fuel-laden. If a bird hit is suspected, the crew have to watch all parameters. There are the usual places where the crew knows the bird hit has occurred, i.e., the windshield, the belly and the engines. Damage to the engines can vary with twisted fan blades, blade separation and vibrations. This could result in an engine imbalance as well. Apart from this there can be damage to the wing surfaces (flaps, spoilers and slats) and the airframe too. This results in huge losses for the airline operator.

He added that there are crew standard/operating procedures laid down by the manufacturers and the airline company, followed by simulator checks. He said adherence to wildlife management rules is imperative within and around the airport and its vicinity.

Captain A. (Mohan) Ranganathan, a former airline instructor pilot and aviation safety adviser — he brought out a bird strike handout when he was part of the Bird Strike Committee in 2011 — told The Hindu that the recent bird hit incidents show that all areas surrounding an airport ought to be clear of slaughter houses and garbage dumping (factors which can attract wildlife and increase risks). Airports are also expected to have incinerators to dispose of garbage removed from aircraft. The expert said that airlines are supposed to have some standard operating procedures for bird strike prevention. He added that for pilots, it is important to have constant monitoring. After lift-off, the pilot flying should have his eyes on the instruments and the pilot not flying has to have his/her eyes outside to look out for birds. This has to be emphasised during training. Finally, he said, understanding bird behaviour is something crew and operators need to be familiar with. Close to the ground, the instinctive response of birds is to get away from the aircraft path. Bird strikes occur when pilots try to climb over them during the initial take-off phase. Birds get sucked into an engine as an aircraft engine’s field of ingestion is quite high with take-off thrust. Over 100ft, birds tend to dive to avoid an aircraft. Therefore, it is important to understand bird behaviour.