Narrative:

Snow accumulation on wings after deicing but prior to takeoff with a return to the gate; and a subsequent refusal of aircraft through dispatch by the captain. During boarding; a moderate snow shower passed over as forecast. The crew took the aircraft to the B de-ice pad and was de-iced with type I fluid; then anti-iced with type iv fluid. Per the hold over timetable the crew figured on a 1 - 1 1/2 min holdover time for anti-icing. After final step of deicing; the crew waited in the B de-ice for ATC taxi instructions for 15 minutes. Holding short #1; a crew member inspected the wings from a cabin vantage point prior to takeoff. The left wing illumination light was inoperative. The crew member could see various shadows of accumulation on the right wing. Nothing could be seen on the left wing with the wing scan light inoperative. The captain elected to return to the gate for the replacement of the wing scan light; and for more fuel. The time span between final de-ice step and return to the gate was 45 minutes; and both wings and fuselage were covered in snow. The crew sent an ACARS to fix wing scan light. Maintenance sent deferral information over ACARS printer for the deferral of the left wing scan light. The captain called dispatch and refused the aircraft through the dispatcher due to the inoperative wing scan light. After refusal; maintenance replaced left wing scan light and issued a new release to the cockpit printer. The MEL does allow for deferral of wing scan lights under all conditions. The MEL further states that the wing scan light doesn't even shine over the top of the wing. However; crew member inspection of wing area after deicing was unsuccessful due to no ambient lighting and poor weather conditions in snow. After replacing wing scan light crew had airplane de-iced a second time at the B de-ice pad. This time wait at end of runway was much shorter; plus snow conditions had moderated. Crew performed a second visual inspection prior to takeoff and made a safe departure afterward. The captain suggests that a B757 aircraft be towed to a remote overnight location with no airport lighting and test the viability of wing scan lights; and the effect of darkness on observations to the top of the wings from the cabin. Then based on testing possibly amend the MEL to require wing scan lights during night and adverse conditions.

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Original NASA ASRS Text

Title: B757 Captain returns to gate to repair inoperative wing inspection light due to inability to perform pre-departure check in snow storm.

Narrative: Snow accumulation on wings after deicing but prior to takeoff with a return to the gate; and a subsequent refusal of aircraft through Dispatch by the Captain. During boarding; a moderate snow shower passed over as forecast. The crew took the aircraft to the B de-ice pad and was de-iced with Type I fluid; then anti-iced with Type IV fluid. Per the hold over timetable the crew figured on a 1 - 1 1/2 min holdover time for anti-icing. After final step of deicing; the crew waited in the B de-ice for ATC taxi instructions for 15 minutes. Holding short #1; a crew member inspected the wings from a cabin vantage point prior to takeoff. The left wing illumination light was inoperative. The crew member could see various shadows of accumulation on the right wing. Nothing could be seen on the left wing with the wing scan light inoperative. The Captain elected to return to the gate for the replacement of the wing scan light; and for more fuel. The time span between final de-ice step and return to the gate was 45 minutes; and both wings and fuselage were covered in snow. The crew sent an ACARS to fix wing scan light. Maintenance sent deferral information over ACARS printer for the deferral of the left wing scan light. The Captain called Dispatch and refused the aircraft through the Dispatcher due to the inoperative wing scan light. After refusal; maintenance replaced left wing scan light and issued a new release to the cockpit printer. The MEL does allow for deferral of wing scan lights under all conditions. The MEL further states that the wing scan light doesn't even shine over the top of the wing. However; crew member inspection of wing area after deicing was unsuccessful due to no ambient lighting and poor weather conditions in snow. After replacing wing scan light crew had airplane de-iced a second time at the B de-ice pad. This time wait at end of runway was much shorter; plus snow conditions had moderated. Crew performed a second visual inspection prior to takeoff and made a safe departure afterward. The Captain suggests that a B757 aircraft be towed to a remote overnight location with no airport lighting and test the viability of wing scan lights; and the effect of darkness on observations to the top of the wings from the cabin. Then based on testing possibly amend the MEL to require wing scan lights during night and adverse conditions.

Data retrieved from NASA's ASRS site as of May 2009 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.