Aircraft parked at gate, brakes off per company procedure, slides back, no damage.

Attributes
ACN	100153
Time
Date	198812
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : pit
State Reference	PA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Flight Phase	ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 15000
ASRS Report	100153
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Airport
Air Traffic Incident	other

Narrative:

Aircraft slid backwards while parked at gate. The nose wheel was chocked and the brakes were released as per procedure. I was signing the aircraft log book when I heard a noise from the cabin. Looking up, I noticed movement of the jetway. Actually, the jetway wasn't moving, the aircraft was sliding rearward. The brakes were applied by both myself and the first officer. The aircraft stopped, brakes were set. The aircraft was towed back to original parking spot and the remaining passenger deplaned. Luckily, no passenger were hurt and the aircraft sustained no damage. Large credit is due to the F/a's quick reaction in stopping the passenger from deplaning. I recommend 3 corrective actions in order to avoid such future incidents: chock main gear when only one is to be chocked, have ramp chocking area cleared of ice and snow or sanded as appropriate, and leave parking brakes set until all passenger have deplaned. Callback conversation with reporter revealed the following: ramp was covered with sleet and the reporter said it was reasonable level. Nose chock had been placed tight against the nose wheel both front and back. First officer was the first to notice movement of the aircraft and set the parking brake. Company has investigated the incident and has changed the procedure to leave the parking brake on during winter months. Should solve the problem.

Original NASA ASRS Text

Title: ACFT PARKED AT GATE, BRAKES OFF PER COMPANY PROC, SLIDES BACK, NO DAMAGE.

Narrative: ACFT SLID BACKWARDS WHILE PARKED AT GATE. THE NOSE WHEEL WAS CHOCKED AND THE BRAKES WERE RELEASED AS PER PROC. I WAS SIGNING THE ACFT LOG BOOK WHEN I HEARD A NOISE FROM THE CABIN. LOOKING UP, I NOTICED MOVEMENT OF THE JETWAY. ACTUALLY, THE JETWAY WASN'T MOVING, THE ACFT WAS SLIDING REARWARD. THE BRAKES WERE APPLIED BY BOTH MYSELF AND THE F/O. THE ACFT STOPPED, BRAKES WERE SET. THE ACFT WAS TOWED BACK TO ORIGINAL PARKING SPOT AND THE REMAINING PAX DEPLANED. LUCKILY, NO PAX WERE HURT AND THE ACFT SUSTAINED NO DAMAGE. LARGE CREDIT IS DUE TO THE F/A'S QUICK REACTION IN STOPPING THE PAX FROM DEPLANING. I RECOMMEND 3 CORRECTIVE ACTIONS IN ORDER TO AVOID SUCH FUTURE INCIDENTS: CHOCK MAIN GEAR WHEN ONLY ONE IS TO BE CHOCKED, HAVE RAMP CHOCKING AREA CLRED OF ICE AND SNOW OR SANDED AS APPROPRIATE, AND LEAVE PARKING BRAKES SET UNTIL ALL PAX HAVE DEPLANED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RAMP WAS COVERED WITH SLEET AND THE RPTR SAID IT WAS REASONABLE LEVEL. NOSE CHOCK HAD BEEN PLACED TIGHT AGAINST THE NOSE WHEEL BOTH FRONT AND BACK. F/O WAS THE FIRST TO NOTICE MOVEMENT OF THE ACFT AND SET THE PARKING BRAKE. COMPANY HAS INVESTIGATED THE INCIDENT AND HAS CHANGED THE PROC TO LEAVE THE PARKING BRAKE ON DURING WINTER MONTHS. SHOULD SOLVE THE PROB.

Data retrieved from NASA's ASRS site as of August 2007 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.