B737 crew has aircraft move 12 inches upon releasing parking brake even though nosewheel was chocked...

Attributes
ACN	704214
Time
Date	200607
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sfo.airport
State Reference	CA
Altitude	agl single value : 0
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 250 flight time type : 11500
ASRS Report	704214
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	other anomaly other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Supplementary
Problem Areas	Company Airport
Primary Problem	Company

Narrative:

With chocks in place (nosewheel) when brakes released aircraft moved 12 inches. Just pure luck that the aircraft; ground equipment/personnel nor any crew/passenger were injured/damaged. The aircraft movement was stopped by the captain (even though I had my seat full back and was getting out of my seat). The checklist had been run and the jetway was not up to the aircraft (thankfully it was in the B747 position; so it was not even close to the plane). Nor had any catering trucks gotten close. And; even with all the passenger standing; it was not a big enough jolt to knock anyone down nor was anyone injured. The ramp was dry and the chock was large but made of wood (so maybe get rubber chocks like most every place else!).

Original NASA ASRS Text

Title: B737 CREW HAS ACFT MOVE 12 INCHES UPON RELEASING PARKING BRAKE EVEN THOUGH NOSEWHEEL WAS CHOCKED.

Narrative: WITH CHOCKS IN PLACE (NOSEWHEEL) WHEN BRAKES RELEASED ACFT MOVED 12 INCHES. JUST PURE LUCK THAT THE ACFT; GND EQUIP/PERSONNEL NOR ANY CREW/PAX WERE INJURED/DAMAGED. THE ACFT MOVEMENT WAS STOPPED BY THE CAPT (EVEN THOUGH I HAD MY SEAT FULL BACK AND WAS GETTING OUT OF MY SEAT). THE CHKLIST HAD BEEN RUN AND THE JETWAY WAS NOT UP TO THE ACFT (THANKFULLY IT WAS IN THE B747 POS; SO IT WAS NOT EVEN CLOSE TO THE PLANE). NOR HAD ANY CATERING TRUCKS GOTTEN CLOSE. AND; EVEN WITH ALL THE PAX STANDING; IT WAS NOT A BIG ENOUGH JOLT TO KNOCK ANYONE DOWN NOR WAS ANYONE INJURED. THE RAMP WAS DRY AND THE CHOCK WAS LARGE BUT MADE OF WOOD (SO MAYBE GET RUBBER CHOCKS LIKE MOST EVERY PLACE ELSE!).

Data retrieved from NASA's ASRS site as of January 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.