THE Civil Aviation Safety Authority has warned pilots to be on alert for locust swarms in north-west Victoria, western New South Wales and South Australia in coming weeks.
In a national notice to pilots issued at the weekend, CASA said locusts could block engine intakes and cause overheating and rough running. It said that if locusts blocked ''pitot'' tubes, the accuracy of instrument readings could be disrupted, posing a substantial threat to safety.
While locusts are likely to be a bigger threat to planes on, or soon after, landing and take-off, CASA said locusts fly at up to 3000 feet and in swarms of up to 50 million, and could disrupt some cruising planes.
Pilots were told that locusts could disguise ground features and reduce visibility as they smashed into windscreens. Locust swarms could also attract hungry birds, increasing the risk of bird strikes.
The expected locust swarms are likely to mean more aircraft activity because planes will be used for surveillance and spraying.
In a media statement released yesterday, CASA said high-density hatchings of locusts had already occurred in the three states and urged pilots to stay informed.
Spokesman Peter Gibson said the bulletin to pilots could be the first time CASA had issued a warning about locusts. He said the warnings were particularly relevant to city-based pilots who might fly into inland areas hit by locusts.
Figures released by the Victorian Department of Primary Industries show 543 reports of locusts since July, including 327 in the Mallee this month.
''There's varying degrees of activity at the sites,'' said Noel Grant, incident manager of the regional locust management centre at Mildura. At a site in Red Cliffs, near Mildura, locusts were estimated at about 2500 per square metre, he said.
Chris Adriaansen, director of the Australian Plague Locust Commission, said aerial spraying of locusts was likely to start in NSW tomorrow.
Mr Adriaansen said authorities would get a better idea of how extensive locust numbers would be in northern Victoria and the NSW Riverina in two or three weeks' time.