Federal authorities tried Thursday to track down an individual who shined a laser into the cockpit of a Northwest Airlines plane coming in to land at O'Hare International Airport.
The DC-9, arriving from Memphis on Wednesday evening, was a quarter-mile from touching down when the pilots reported a green or white light aimed at the cockpit from the ground, according to the Federal Aviation Administration.
The plane landed without incident and no injuries were reported, said FAA spokeswoman Elizabeth Isham Cory.
The easy availability in recent years of inexpensive pen-style lasers and pointers has led to more incidents of the intensely bright lights being shined at low-flying aircraft, officials said.
FAA research has found that some lasers could temporarily disorient or disable a pilot during critical phases of flight, such as takeoff and landing. Permanent eye damage has been reported in a few cases.
"The FBI takes these matters very seriously due to the potential impact it could have on the flight crew and passengers," said FBI spokeswoman Cynthia Yates.
FBI agents focused their search just east of O'Hare. Northwest Flight 352 was landing to the west when the laser was shined at the cockpit, officials said.
The FAA was assisting the FBI in narrowing the area from which the beam originated, officials said.
Aiming a light at a plane is considered an attempt to disable the aircraft, a federal crime punishable by up to 20 years in prison.
There have been more than 400 incidents reported since 1990 nationwide. A string of about 30 incidents was reported in late 2004 to early 2005, with seven occurring in one weekend, according to the U.S. Department of Transportation.
Homeland security officials determined that none of the incidents were connected to terrorism, although authorities have said that terrorist groups have considered using lasers to try to bring down planes.
The FAA has stepped up efforts to alert pilots to areas where lasers have been sighted. Since 2005, pilots have been required to report any laser incidents to air-traffic controllers. The information is immediately turned over to local police and the FBI, officials said.