Narrative:

Sitting in the runway holding pad waiting out an indefinite departure delay; both engines shut down; APU running electrical and pneumatics. At 1hr 50 min into hold the cockpit began to have an acute odor that was likened to acetone. It was very strong and sudden onset. All three cockpit crewmembers noted the odor. Advised flight attendants to ascertain if there was any odor in cabin; to which we learned only a small odor of acetone between first and business cabin. The odor persisted at which time all cockpit crewmembers donned oxygen masks; established communications and the qrc was followed. Upon communications with ground we returned to the gate; though there were severe thunderstorms impacting the airport and the ramp was on stand down; accommodations were made for us at the gate and emergency crash fire rescue equipment was dispatched and waited for us at gate. Hazmat personnel were also at gate. Once engines were started and APU bleed use discontinued the odor immediately subsided. The crew remained on oxygen during taxi to gate for precautionary measures. Upon inspection of aircraft cargo and cabin and review of maintenance history; the aircraft was returned to service 3 hours later and we continued on to our destination.

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Original NASA ASRS Text

Title: A B777 flight crew noticed a strong acetone odor while waiting for takeoff with engines shut down and APU supplying air. They donned oxygen masks and returned to the gate.

Narrative: Sitting in the runway holding pad waiting out an indefinite departure delay; both engines shut down; APU running electrical and pneumatics. At 1hr 50 min into hold the cockpit began to have an acute odor that was likened to acetone. It was very strong and sudden onset. All three cockpit crewmembers noted the odor. Advised flight attendants to ascertain if there was any odor in cabin; to which we learned only a small odor of acetone between first and business cabin. The odor persisted at which time all cockpit crewmembers donned oxygen masks; established communications and the QRC was followed. Upon communications with Ground we returned to the gate; though there were severe thunderstorms impacting the airport and the ramp was on stand down; accommodations were made for us at the gate and emergency CFR was dispatched and waited for us at gate. HAZMAT personnel were also at gate. Once engines were started and APU bleed use discontinued the odor immediately subsided. The crew remained on oxygen during taxi to gate for precautionary measures. Upon inspection of aircraft cargo and cabin and review of maintenance history; the aircraft was returned to service 3 hours later and we continued on to our destination.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.