US pilots targeted by mysterious laser flashes

The FBI is investigating six incidents over the past four days in which commercial aircraft pilots were flashed by lasers while preparing to land.

The authorities said they did not know whether the incidents were the result of children playing with Christmas toys or something more sinister and organised. It has been claimed that terrorists may use such devices to try to crash an aircraft, though so far there is no evidence of such a motive in these incidents.

In one of the latest incidents, which took place on Monday, the cockpit of a Continental Airlines plane was illuminated by a green laser when about 15 miles from landing at Cleveland Hopkins International Airport in Ohio. The plane, which was flying at 10,000ft at the time, later landed safely. Robert Hawk, of the FBI, said: "We don't know if it was a prank or if someone was trying to do something illegal. We just want to know what happened and why."

On the same day, the crews of two aircraft approaching Colorado Springs reported green, pulsating lights flashing into their cockpits. The passenger plane and the cargo aircraft later landed safely.

The authorities have previously claimed that terrorists could use such lasers. In November, the FBI and the Department of Homeland Security sent an intelligence bulletin to police agencies claiming that terrorist groups have shown an interest in using the beams to try to bring down airliners. The bulletin said: "Terrorist groups overseas have expressed interest in using these devices against human sight. The US intelligence community has no specific or credible evidence that terrorists intend to use lasers to target pilots in the homeland."

The bulletin also said that lasers were not a proven method of attacking aircraft but that they could lead to a crash. "In certain circumstances, if laser weapons adversely affect the eyesight of both pilot and co-pilot during a non-instrument approach, there is a risk of airliner crash," it said.

CNN reported yesterday that government officials had said the six aircraft that had reported being illuminated by the lasers were from "all over the place [and in] kind of odd places". One of the government officials said it was not clear whether these incidents were the result of "kids who got a laser light for Christmas" or a deliberate attempt to target the aircraft.

The Federal Aviation Authority said it was possible that the eyesight of pilots could be damaged by such lasers. A report issued in June found that of 34 pilots who were targeted by lasers during simulated flights, more than 65 per cent experienced adverse visual effects, even at the lowest level of exposure. Higher levels of exposure resulted in much greater problems for them and even forced some of the pilots to abort their simulated landings.

The report said: "Illumination by a laser beam at night can distract pilots and even cause fatalities if it occurs during a critical phase in the flight."