A B757-200's parking brake failed to set after the aircraft was stopped at the gate with the engines...

Attributes
ACN	853830
Time
Date	200909
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Night
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Component
Aircraft Component	Parking Brake
Person 1
Function	First Officer Pilot Not Flying
Person 2
Function	Pilot Flying Captain
Events
Anomaly	Aircraft Equipment Problem Critical Conflict Ground Conflict Critical Ground Event / Encounter Loss Of Aircraft Control

Narrative:

The captain set the parking brake and the parking brake light came on. I proceeded to make my arrival PA then noticed the jetbridge moving toward the L2 door in my peripheral vision. I realized that it was the plane that was moving; because halfway through my arrival PA; the plane jerked to a stop. I noticed the brakes had released. I was just finishing up my arrival PA when I felt the plane stop suddenly again. We were not moving very much but evidently it was catching the captain by surprise and he immediately pressed on the brakes to stop the movement. After the engines were off the brakes managed to stay engaged. The captain wrote up the brakes; and I will submit a report also. I will make sure from now on that the brakes remain set while I'm making my PA.

Original NASA ASRS Text

Title: A B757-200's parking brake failed to set after the aircraft was stopped at the gate with the engines running. The aircraft continued a slow taxi until the startled Captain reset the brakes.

Narrative: The Captain set the parking brake and the parking brake light came on. I proceeded to make my arrival PA then noticed the jetbridge moving toward the L2 door in my peripheral vision. I realized that it was the plane that was moving; because halfway through my arrival PA; the plane jerked to a stop. I noticed the brakes had released. I was just finishing up my arrival PA when I felt the plane stop suddenly again. We were not moving very much but evidently it was catching the Captain by surprise and he immediately pressed on the brakes to stop the movement. After the engines were off the brakes managed to stay engaged. The Captain wrote up the brakes; and I will submit a report also. I will make sure from now on that the brakes remain set while I'm making my PA.

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.

A B757-200's parking brake failed to set after the aircraft was stopped at the gate with the engines running. The aircraft continued a slow taxi until the startled captain reset the brakes.