Air Canada A320 near Chicago on Sep 17th 2011, cracked windshield

Last Update: November 8, 2012 / 12:19:40 GMT/Zulu time

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Photo of Air Canada C-FGYL, Airbus A320 — Air Canada C-FGYL, Airbus A320 (Photo credit: airlines470 / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Sep 17, 2011

Classification
Incident

Cause
Cracked windshield

Airline
Air Canada

Flight number
AC-791

Departure
Toronto, Canada

Destination
Los Angeles, United States

Aircraft Registration
C-FGYL

Aircraft Type
Airbus A320

ICAO Type Designator
A320

An Air Canada Airbus A320-200, registration C-FGYL performing flight AC-791 from Toronto,ON (Canada) to Los Angeles,CA (USA) with 131 passengers and 5 crew, was enroute at FL340 about 90nm northwest of Chicago's O'Hare Airport when the first officer's windshield cracked. The crew descended the aircraft to FL230 and diverted to Chicago O'Hare for a safe landing on runway 14R about 25 minutes later.

The Canadian TSB reported the NTSB rated the occurrence a serious incident and requested the download of the black boxes. The window will undergo testing under supervision of the NTSB.

NAV Canada reported FAA staff had reported the windscreen shattered.

The NTSB reported on Sep 23rd 2011, that the aircraft sustained minor damage when the first officer's windshield cracked during cruise at FL340, no injuries occurred. The window will undergo detailed examinations, the flight data recorder information will be reviewed.

A replacement Airbus A320-200 registration C-GKOD reached Los Angeles with a delay of 5:45 hours.

On Sep 22nd 2012 the NTSB released their factual report stating that the crew had detected an 18 inch/45cm long crack on the first officer's windshield extending from the left bottom to the top right corner of the windshield that progressed into multiple multidirectional cracks obscuring the first officer's view through the windshield. The crew was unable to determine how many layers of the windshield were affected.

The NTSB report does not mention, too, which layers were affected, however reported examination of the windshield revealed " that the fracture origin was located at the center of the windshield. An area of arcing was located along the electrical bus bar at the lower edge of the windshield, near the forward corner. This location coincided with the area in which the power and sensing element wires were routed around the structural glass plies. This area of arcing was surrounded by a cloudy and degraded interlayer, which was consistent with the presence of moisture. The moisture seal was worn and the moisture seal upper edge had been repaired. Appearance of the moisture sealÂ’s forward and lower edges was consistent with a factory condition."

The NTSB reported that Airbus had released a revised a flight operation telex on May 25th 2011 informing operators about a revised cockpit operational procedure regarding cracked windshields, which now asks crew to check whether the inner ply (layer) is cracked by the use of a pen of finger nails, if the inner ply is not affected the flight can be continued without other restriction.

A new windshield design has been introduced as well reducing the probability of moisture ingress and affects onto the electrical system.

On Nov 8th 2012 the NTSB released their final report concluding the probable cause was:

The infiltration of moisture into the windshield heating layer that induced arcing in the heating system that subsequently cracked the windshield.