B727 damaged when it jumped the nosewheel chock during an engine start pushback procedure. Brakes ha...

Attributes
ACN	364891
Time
Date	199703
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pdx
State Reference	OR
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Flight Phase	other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 15000 flight time type : 11000
ASRS Report	364891
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
ASRS Report	365018
Events
Anomaly	aircraft equipment problem : critical non adherence : published procedure other anomaly other anomaly other
Independent Detector	other flight crewa other other : unspecified
Resolutory Action	none taken : insufficient time
Consequence	other Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Flight, pdx-cvg. Aircraft ready for pushback, ground crew could not get aft airstairs to stay up and locked. Mechanic requested we open the hydraulic ground interconnect. The aft airstairs were stowed up and locked, light out on so panel. The tug driver then requested we 'open' interconnect. I replied 'you must mean close the interconnect.' he said okay that must be it. Driver had an accent and was hard for me to understand. On pushback we were cleared to start. After #1 engine started and during #2 start, so indicated we might have low system 'a' hydraulic pressure. After #2 engine started we were showing 1800 psi -- minimum was 2800 psi. We reached end of pushback and tug driver requested brakes set. I set the brakes and responded 'brakes set.' I told the driver to 'stay with me' and added 'I think we are going to have to return to the gate.' he said okay. My intention was to have him pull me back to the gate. So was talking to maintenance on radio and checking MEL and pom. We still had 1800 psi showing. I told tug driver we needed to return to gate. He replied 'okay' and added something I interpreted as 'brakes released.' I released the brakes and unknown to me tow bar had been disconnected. Nosegear jumped the chock which, it turned out, belonged to another airline and was smooth and worn. Tow bar damaged nosegear before I could reapply brakes. I did not clear tug driver to 'disconnect' and because I told him we would probably return to the gate did not expect the tow bar to be disconnected. The ground crew procedure, we learned, is to immediately begin disconnecting tow bar as soon as brakes are set. This procedure and communications between cockpit and ground are being reviewed. No one was injured and perhaps we will get a positive result from this event. Supplemental information from acn 365018: we taxied back to the gate and the flight was eventually (20 mins later) canceled.

Original NASA ASRS Text

Title: B727 DAMAGED WHEN IT JUMPED THE NOSEWHEEL CHOCK DURING AN ENG START PUSHBACK PROC. BRAKES HAD BEEN SET AND WERE PREMATURELY RELEASED WHEN THE GND CREW AND FLC GOT 'OUT OF SYNCH' WITH EACH OTHER. A DEFICIENCY IN THE ACR PROCS.

Narrative: FLT, PDX-CVG. ACFT READY FOR PUSHBACK, GND CREW COULD NOT GET AFT AIRSTAIRS TO STAY UP AND LOCKED. MECH REQUESTED WE OPEN THE HYD GND INTERCONNECT. THE AFT AIRSTAIRS WERE STOWED UP AND LOCKED, LIGHT OUT ON SO PANEL. THE TUG DRIVER THEN REQUESTED WE 'OPEN' INTERCONNECT. I REPLIED 'YOU MUST MEAN CLOSE THE INTERCONNECT.' HE SAID OKAY THAT MUST BE IT. DRIVER HAD AN ACCENT AND WAS HARD FOR ME TO UNDERSTAND. ON PUSHBACK WE WERE CLRED TO START. AFTER #1 ENG STARTED AND DURING #2 START, SO INDICATED WE MIGHT HAVE LOW SYS 'A' HYD PRESSURE. AFTER #2 ENG STARTED WE WERE SHOWING 1800 PSI -- MINIMUM WAS 2800 PSI. WE REACHED END OF PUSHBACK AND TUG DRIVER REQUESTED BRAKES SET. I SET THE BRAKES AND RESPONDED 'BRAKES SET.' I TOLD THE DRIVER TO 'STAY WITH ME' AND ADDED 'I THINK WE ARE GOING TO HAVE TO RETURN TO THE GATE.' HE SAID OKAY. MY INTENTION WAS TO HAVE HIM PULL ME BACK TO THE GATE. SO WAS TALKING TO MAINT ON RADIO AND CHKING MEL AND POM. WE STILL HAD 1800 PSI SHOWING. I TOLD TUG DRIVER WE NEEDED TO RETURN TO GATE. HE REPLIED 'OKAY' AND ADDED SOMETHING I INTERPRETED AS 'BRAKES RELEASED.' I RELEASED THE BRAKES AND UNKNOWN TO ME TOW BAR HAD BEEN DISCONNECTED. NOSEGEAR JUMPED THE CHOCK WHICH, IT TURNED OUT, BELONGED TO ANOTHER AIRLINE AND WAS SMOOTH AND WORN. TOW BAR DAMAGED NOSEGEAR BEFORE I COULD REAPPLY BRAKES. I DID NOT CLR TUG DRIVER TO 'DISCONNECT' AND BECAUSE I TOLD HIM WE WOULD PROBABLY RETURN TO THE GATE DID NOT EXPECT THE TOW BAR TO BE DISCONNECTED. THE GND CREW PROC, WE LEARNED, IS TO IMMEDIATELY BEGIN DISCONNECTING TOW BAR AS SOON AS BRAKES ARE SET. THIS PROC AND COMS BTWN COCKPIT AND GND ARE BEING REVIEWED. NO ONE WAS INJURED AND PERHAPS WE WILL GET A POSITIVE RESULT FROM THIS EVENT. SUPPLEMENTAL INFO FROM ACN 365018: WE TAXIED BACK TO THE GATE AND THE FLT WAS EVENTUALLY (20 MINS LATER) CANCELED.

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.

B727 damaged when it jumped the nosewheel chock during an engine start pushback procedure. Brakes had been set and were prematurely released when the ground crew and flight crew got 'out of synch' with each other. A deficiency in the air carrier procedures.