Serious incident Boeing 737-522 N930UA, Wednesday 16 April 1997

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Date:	Wednesday 16 April 1997
Time:	21:10 LT
Type:	Boeing 737-522
Owner/operator:	United Airlines
Registration:	N930UA
MSN:	26655/2274
Year of manufacture:	1992
Total airframe hrs:	15042 hours
Engine model:	Cfm CFM56-3C
Fatalities:	Fatalities: 0 / Occupants: 100
Other fatalities:	0
Aircraft damage:	None
Category:	Serious incident
Location:	Rialto, CA - United States of America
Phase:	Approach
Nature:	Unknown
Departure airport:	San Fransisco, CA (SFO
Destination airport:	Ontario, CA (KONT)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The aircraft was on a standard instrument arrival when the captain, who was on the controls, noticed a green light illuminating the aircraft. It appeared to him that the light was tracking the aircraft, but as he pointed out that fact to the first officer, the light disappeared. The captain reported that although the light caused a minimal yet persistent loss of night vision, he was able to maintain control of the aircraft throughout the remainder of the flight. He told ATC that the light appeared to emanate from the western edge of the city. A medical examination by Air Force specialists revealed no permanent evidence of eye damage. Investigators were unable to locate the source of the light. There were no NOTAMs for laser light activity at the time of the incident.

Probable Cause: a laser light source of undetermined origin, directed by unknown person(s) toward the cockpit window of the aircraft, while the aircraft was on an approach to land.

Accident investigation: