Chinanews, Beijing, June 22 – Recently, some pigeons have flown over the Capital Airport and hit planes constantly. Fortunately, no accidents have been caused to the planes so far.Every day, more than 100 pigeons are found flying above the Capital Airport. The pigeons may cause many planes to delay their flights. Sometimes, they can even damage the plane and kill passengers on board. The administrative staff in the Capital Airport fear that these pigeons may, one day, inflict some casualties. They urge that the authorities issue some laws to prohibit pigeons from flying near the Capital Airport, an official at the Capital Airport told this reporter.Most of these pigeons are raised by local residents who live near the airport. Every day, they will let their pigeons fly for a while for exercise. The Capital Airport has thus become an ideal place for pigeons to practice flying.As birds tend to fly a lot between March and October, this has become a busiest time for airport workers. They have taken many measures in order to scare away these intruders. The measures include firing cannons, setting up some iron grids near the runways.In addition to these measures, the Capital Airport workers have purchased advanced devices that are used to keep away birds. The devices can send out sounds similar to hawks' or big birds' to keep away those small birds. The workers at the Capital Airport will fire cannon balls once every 30 minutes. Some workers will patrol around the airport to see if there are birds hovering near the runways. Once they find some “intruders”, the workers will fire cannon balls to drive them away.