Narrative:

Two company maintenance technicians were assigned to move an empty aircraft from the international terminal to the domestic terminal for an outbound flight. One mechanic had just entered aircraft as the other unplugged the jetway power in preparation for a high speed tow operation. Just as the mechanic detached the power cord; a gust of wind caused the aircraft to 'weather vane' at the gate. The aircraft pivoted on the main landing gear and the nose of the aircraft went into an uncontrolled excursion of between twenty five and forty feet. Neither mechanic was injured. The main gear and nose gear were all chocked. The main gear chocks were simply displaced by the tires. The nose gear chocks were not displaced; but had no effect on the lateral movement of the [aircraft] excursion. The aircraft was removed from revenue service and taken to a hangar for inspection. This is the third incidence in several months of company aircraft 'weather vaning' at a gate. A previous incident pulled an attached tow tractor along with the aircraft. My air carrier has a new policy of 'brakes off;' when an aircraft is in a gate. Most other air carriers do not allow brakes off at a gate. My air carrier has only recently instituted such a policy in order to facilitate a faster movement of aircraft without the necessity of a person in the cockpit. It may work fine in [some locations]; but should not be promoted in [very] windy locations. My air carrier says they have a policy of setting the brakes in high winds; but these conditions are transient and conditional; and therefore have no place as a policy when adverse weather conditions pop up at random times. Aircraft can also be 'weather vaned' by [other] aircraft [movement] at breakaway thrust. This potentially dangerous aircraft handling practice can only be resolved by consistently setting aircraft brakes at all times when an aircraft is in the gate.

Google
 

Original NASA ASRS Text

Title: A Lead Mechanic reports how company policy of requiring 'brakes-Off' on aircraft at domestic and international terminals; has contributed to multiple incidents in one month; of aircraft that 'weather-vaned' off the gates due to windy conditions. B737NG aircraft appear to be more susceptible.

Narrative: Two company maintenance technicians were assigned to move an empty aircraft from the International Terminal to the Domestic Terminal for an outbound flight. One Mechanic had just entered aircraft as the other unplugged the jetway power in preparation for a high speed tow operation. Just as the Mechanic detached the power cord; a gust of wind caused the aircraft to 'weather vane' at the gate. The aircraft pivoted on the main landing gear and the nose of the aircraft went into an uncontrolled excursion of between twenty five and forty feet. Neither Mechanic was injured. The main gear and nose gear were all chocked. The main gear chocks were simply displaced by the tires. The nose gear chocks were not displaced; but had no effect on the lateral movement of the [aircraft] excursion. The aircraft was removed from revenue service and taken to a hangar for inspection. This is the third incidence in several months of company aircraft 'weather vaning' at a gate. A previous incident pulled an attached tow tractor along with the aircraft. My Air Carrier has a new policy of 'brakes off;' when an aircraft is in a gate. Most other air carriers do not allow brakes off at a gate. My Air Carrier has only recently instituted such a policy in order to facilitate a faster movement of aircraft without the necessity of a person in the cockpit. It may work fine in [some locations]; but should not be promoted in [very] windy locations. My Air Carrier says they have a policy of setting the brakes in high winds; but these conditions are transient and conditional; and therefore have no place as a policy when adverse weather conditions pop up at random times. Aircraft can also be 'weather vaned' by [other] aircraft [movement] at breakaway thrust. This potentially dangerous aircraft handling practice can only be resolved by consistently setting aircraft brakes at all times when an aircraft is in the gate.

Data retrieved from NASA's ASRS site as of July 2013 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.