B767. Flight crew released the brakes after they were chocked at the gate. The aircraft rolled back ...

Attributes
ACN	622386
Time
Date	200401
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Flight Conditions	IMC
Weather Elements	Ice Snow Fog
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B767 Undifferentiated or Other Model
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 : 217 flight time total : 17500 flight time type : 3000
ASRS Report	622386
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : ground critical inflight encounter : weather other anomaly
Independent Detector	other flight crewa other other : 3
Resolutory Action	flight crew : regained aircraft control other
Supplementary
Problem Areas	Company Airport Weather
Primary Problem	Company

Narrative:

Parking was normal at gate in moderate snow with a marshaller and 2 wingmen. Got chocks-in signal. I released the brakes and we ran the parking check. A min or so later, I noticed the jetway moving. On looking more closely, it was the aircraft rolling backwards, not the jetway, which was moving. I immediately applied brakes as rapidly as possible, mindful of everyone standing up in the cabin. Looking forward, I then saw a frantic marshaller picking his flashlight/wands up out of the snow to give me a set brakes signal. He came onto the headset and said that we had rolled back about 8 ft in the snow and ice, the chocks having simply been pushed along, unable to hold the airplane on the sloping ramp. He said that just walking on the ice and snow was extremely hazardous. He was very excited, as he said that his foot was nearly run over, but I had stopped just in time. No one was injured on the ground or in the airplane. I left the brakes set before departing the aircraft. I could find nothing in our manuals giving non-standard guidance for this occurrence. Talking to my brothers who are widebody transport capts at air carrier Y and air carrier Z, I learned that their flight crews never release the brakes after parking -- it is always left to the mechanics. I believe we should consider modifying our parking procedures in ice or snow. I will never release the brakes again under such conditions.

Original NASA ASRS Text

Title: B767. FLT CREW RELEASED THE BRAKES AFTER THEY WERE CHOCKED AT THE GATE. THE ACFT ROLLED BACK 8 FT AFTER THE CHOCKS DID NOT HOLD ON AN ICY RAMP.

Narrative: PARKING WAS NORMAL AT GATE IN MODERATE SNOW WITH A MARSHALLER AND 2 WINGMEN. GOT CHOCKS-IN SIGNAL. I RELEASED THE BRAKES AND WE RAN THE PARKING CHK. A MIN OR SO LATER, I NOTICED THE JETWAY MOVING. ON LOOKING MORE CLOSELY, IT WAS THE ACFT ROLLING BACKWARDS, NOT THE JETWAY, WHICH WAS MOVING. I IMMEDIATELY APPLIED BRAKES AS RAPIDLY AS POSSIBLE, MINDFUL OF EVERYONE STANDING UP IN THE CABIN. LOOKING FORWARD, I THEN SAW A FRANTIC MARSHALLER PICKING HIS FLASHLIGHT/WANDS UP OUT OF THE SNOW TO GIVE ME A SET BRAKES SIGNAL. HE CAME ONTO THE HEADSET AND SAID THAT WE HAD ROLLED BACK ABOUT 8 FT IN THE SNOW AND ICE, THE CHOCKS HAVING SIMPLY BEEN PUSHED ALONG, UNABLE TO HOLD THE AIRPLANE ON THE SLOPING RAMP. HE SAID THAT JUST WALKING ON THE ICE AND SNOW WAS EXTREMELY HAZARDOUS. HE WAS VERY EXCITED, AS HE SAID THAT HIS FOOT WAS NEARLY RUN OVER, BUT I HAD STOPPED JUST IN TIME. NO ONE WAS INJURED ON THE GND OR IN THE AIRPLANE. I LEFT THE BRAKES SET BEFORE DEPARTING THE ACFT. I COULD FIND NOTHING IN OUR MANUALS GIVING NON-STANDARD GUIDANCE FOR THIS OCCURRENCE. TALKING TO MY BROTHERS WHO ARE WDB CAPTS AT ACR Y AND ACR Z, I LEARNED THAT THEIR FLT CREWS NEVER RELEASE THE BRAKES AFTER PARKING -- IT IS ALWAYS LEFT TO THE MECHS. I BELIEVE WE SHOULD CONSIDER MODIFYING OUR PARKING PROCS IN ICE OR SNOW. I WILL NEVER RELEASE THE BRAKES AGAIN UNDER SUCH CONDITIONS.

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

B767. Flight crew released the brakes after they were chocked at the gate. The aircraft rolled back 8 ft after the chocks did not hold on an icy ramp.