Pwrback off ramp. - NASA ASRS

Attributes
ACN	296220
Time
Date	199502
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : lit
State Reference	AR
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Night
Aircraft 1
Controlling Facilities	tower : sxm
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	ground other : taxi other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : private pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 120 flight time total : 13588 flight time type : 6700
ASRS Report	296220
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	other anomaly other other anomaly other
Independent Detector	other flight crewa other other : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

During pwrback, both aircraft main gear left the hard surface of the ramp area. The pwrback appeared normal until the coordinator gave the come ahead signal. Almost simultaneously with moving the thrust levers to the forward thrust position, the aircraft backed off the hard surface. The engines were subsequently shut down and the passenger deplaned through the main cabin door using portable stairs. The aircraft was then towed back to the gate where a maintenance inspection revealed no structural damage. The ramp is unlighted and this was a night pwrback. The ramp was also dry, and the only restr to visibility was the darkness. A short pwrback was all that was necessary, but the coordinator continued to power us back, probably to make the turn out easier for us. As it was a turning pwrback, the coordinator may not have anticipated a problem with the back of the ramp. Even after the main gear left the ramp, it did not appear that the coordinator was aware of a problem as he continued to give us the 'come straight ahead' signal. If the wing walker made any attempt to stop the pwrback, I did not notice it as I was fully concentrating on the coordinator's signals.

Original NASA ASRS Text

Title: PWRBACK OFF RAMP.

Narrative: DURING PWRBACK, BOTH ACFT MAIN GEAR LEFT THE HARD SURFACE OF THE RAMP AREA. THE PWRBACK APPEARED NORMAL UNTIL THE COORDINATOR GAVE THE COME AHEAD SIGNAL. ALMOST SIMULTANEOUSLY WITH MOVING THE THRUST LEVERS TO THE FORWARD THRUST POS, THE ACFT BACKED OFF THE HARD SURFACE. THE ENGS WERE SUBSEQUENTLY SHUT DOWN AND THE PAX DEPLANED THROUGH THE MAIN CABIN DOOR USING PORTABLE STAIRS. THE ACFT WAS THEN TOWED BACK TO THE GATE WHERE A MAINT INSPECTION REVEALED NO STRUCTURAL DAMAGE. THE RAMP IS UNLIGHTED AND THIS WAS A NIGHT PWRBACK. THE RAMP WAS ALSO DRY, AND THE ONLY RESTR TO VISIBILITY WAS THE DARKNESS. A SHORT PWRBACK WAS ALL THAT WAS NECESSARY, BUT THE COORDINATOR CONTINUED TO PWR US BACK, PROBABLY TO MAKE THE TURN OUT EASIER FOR US. AS IT WAS A TURNING PWRBACK, THE COORDINATOR MAY NOT HAVE ANTICIPATED A PROB WITH THE BACK OF THE RAMP. EVEN AFTER THE MAIN GEAR LEFT THE RAMP, IT DID NOT APPEAR THAT THE COORDINATOR WAS AWARE OF A PROB AS HE CONTINUED TO GIVE US THE 'COME STRAIGHT AHEAD' SIGNAL. IF THE WING WALKER MADE ANY ATTEMPT TO STOP THE PWRBACK, I DID NOT NOTICE IT AS I WAS FULLY CONCENTRATING ON THE COORDINATOR'S SIGNALS.

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.