MANILA, Philippines — A bird strike — sometimes called birdstrike, avian ingestion (only if in an engine), bird hit, or BASH (for Bird Aircraft Strike Hazard)— is a collision between an airborne animal (usually a bird or bat) and a man-made vehicle, especially aircraft.

Bird strikes are a significant threat to flight safety, and have caused a number of accidents with human casualties. In January, 2009, a US Airways jet crash-landed in the Hudson River after a flock of birds apparently struck its engines, but all 155 people on board were kept safe.

Most accidents occur when the birds hits the windscreen or flies into the engines. Bird strikes happen most often during takeoff or landing, or during low-altitude flight. It sometimes happens even at high altitudes.

The CAAP Birdstrike Incident Report said that since the start of the year, there have been  16 cases of bird strikes in 11 airports — four at the new Davao International Airport alone and three at the Ninoy Aquino International Airport.

According to Director-General Ramon Gutierrez, chief of the Civil Aviation Authority of the Philippines, the CAAP installed Audio Control repellent systems (ACRS), a bird avoidance technology, in Tacloban, Bacolod, and Iloilo airports early this year. The device will also be installed in 11 other airports.

He said getting priority for this bird-avoidance technology in major alternate international airports is part of President Aquino’s open-skies policy to attract foreign airliners to operate out of provincial airports instead of concentrating in Manila.

Costing R3 million per piece, the ACRS is but one of several means by which the CAAP is trying to limit the number of collisions with airplanes, which in 2010 were recorded at more than a hundred all over the country.

Ed Costes, the chief of the Aerodrome Development and Management Service, said that aside from relying on piercing sounds emitted by the machine to discourage birds from congregating at major airports, they have also focused on the control of vegetation, such as cutting trees and bushes around airports, the usual nesting sites of birds.

The bird problem is different at every airport all over the world. There is an effort to establish newer airports in areas away from wetlands together with control of the environment around the airport. Other measures use simple traditional concepts to scare off or chase off birds.

Costes said they would like to duplicate a trend started in Singapore, where aviation authorities there constructed an area where birds could feed, nest, or breed, far away from the airport. He said this technique is being advised among provincial airport managers, where garbage dumps are located some distance away from the runway so that birds could feed without getting in the way of landing and taking-off airplanes.