A Los Angeles bound Boeing 757 that took off from New York JFK airport diverted to Dulles International airport on the evening of 16 May after experiencing a cockpit fire in cruise at 36,000ft (10,973m) early in the flight.
A source familiar with the incident tells ATI and Flightglobal that pilots of United Flight 27, with 105 passengers and seven crew, noted the faint smell of smoke before hearing a "sizzle" and seeing flames coming from a phenolic block that holds wires that carry power to the windshield heaters. After donning oxygen masks, the crew extinguished the fire with a halon fire extinguisher, declared an emergency and diverted to Dulles.
Inbound to Dulles at approximately 500ft altitude on the final approach to Runway 19L, the Boeing 757's left front windshield apparently shattered with a "boom", according to a report from the crew. Despite the disruption, the pilots landed the aircraft without incident as fire and rescue crews looked on. There were no reported injuries.
United Airlines could not immediately be reached for comment.
The source tells ATI the windscreen on the aircraft, N510UA, has been replaced but airline officials continue to inspect the aircraft's electrical system to determine why the circuit breaker for the heater system did not deactivate the circuit.
The same aircraft was involved in a smoke event on 15 May when it diverted in Las Vegas. Upon investigation however, United determined the problem in that incident had originated from the forward galleys and replaced two ovens.
It's not clear if the problem is linked to several airworthiness directives aimed at wiring on the heaters. The FAA has recently proposed fining Northwest Airlines for operating Boeing 757 aircraft without performing windshield wiring inspections required by a 1990 airworthiness directive linked to undersized wires that could catch fire. Northwest and Delta Air Line merged in 2008.