An A320 rolled backwards at the gate after the parking brake apparently failed to set properly.

Attributes
ACN	870136
Time
Date	201001
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Parking Brake
Person 1
Function	Pilot Not Flying First Officer
Experience	Flight Crew Last 90 Days 250 Flight Crew Total 13000 Flight Crew Type 6200
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy

Narrative:

We arrived at gate. The captain set the parking brake and announced brakes set. While turning the APU generator on and the number 2 generator back on I noticed the aircraft appeared to be moving backwards. At the same moment I was announcing the aircraft was moving the captain stopped the movement with the toe brakes. We rolled back approximately 4 ft. We both looked at the parking brake switch and it was on. The captain reset the parking brake; checked the pressure and the brakes reset. No incident occurred from the aircraft rolling backwards. This was the first time I have seen this happen in my 6;000 plus hours on the airbus. Maintenance was advised of the problem.

Original NASA ASRS Text

Title: An A320 rolled backwards at the gate after the parking brake apparently failed to set properly.

Narrative: We arrived at gate. The Captain set the parking brake and announced brakes set. While turning the APU generator on and the number 2 generator back on I noticed the aircraft appeared to be moving backwards. At the same moment I was announcing the aircraft was moving the Captain stopped the movement with the toe brakes. We rolled back approximately 4 FT. We both looked at the parking brake switch and it was on. The Captain reset the parking brake; checked the pressure and the brakes reset. No incident occurred from the aircraft rolling backwards. This was the first time I have seen this happen in my 6;000 plus hours on the Airbus. Maintenance was advised of the problem.

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.