Narrative:

We taxied from the air cargo ramp at phl just prior to xb:00 on 12/fri/90. Snow had been falling since mid afternoon. WX at the time of taxi was indefininte 300' obscured, visibility 3/8 mi in snow and fog. Runway 9L was open: RVR was reported to us by ground control at RVR 3500. Runway 9R was closed with snowplows attempting to clear it. The cargo ramp had not been plowed. There was 4-6' of snow on all parts of the cargo ramp, with no markings visible. The only lights visible were two green centerline lights on taxiway 'Q' ahead of us. More importantly, we realized afterwards that there are no edge lights on the ramp. We taxied forward to where we believed we would be able to turn right onto taxiway 'Q' on our way to runway 9L. After a short taxi we saw grass sticking out of the snow about 25' ahead of us. We attempted to turn left to stay on what we believed was the ramp. However, we had already taxied off of the prepared surface but did not realize it. We were notified we were in the grass by ground personnel who came up to the aircraft and told us through intercom. The aircraft was shut down after notifying ground control. I believe this occurred because the entire ramp was obscured under snow and that no clear markings or edge lights are present on the cargo ramp. There needs to be some lighting demarking the edge of the prepared surface. Also, keeping the cargo ramp plowed would have greatly assisted in identing where the pavement ended. Plowing on the cargo ramp did not start until after our aircraft became stuck. Callback conversation with reporter revealed the following information. Reporter states there was a blizzard beginning to blow and probably should have asked for a 'follow me' truck or just stayed put. There is a kind of veh driver area and as aircraft began to taxi a truck was coming right toward aircraft. Crew moved to right to assure clearing the truck and could not determine that they were so near the edge. A day and a half later when aircraft was being moved there were centerline lights visible. The were just totally covered at the time of event.

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Original NASA ASRS Text

Title: CARGO FLT TAXIED OFF RAMP AREA COVERED WITH SNOW.

Narrative: WE TAXIED FROM THE AIR CARGO RAMP AT PHL JUST PRIOR TO XB:00 ON 12/FRI/90. SNOW HAD BEEN FALLING SINCE MID AFTERNOON. WX AT THE TIME OF TAXI WAS INDEFININTE 300' OBSCURED, VISIBILITY 3/8 MI IN SNOW AND FOG. RWY 9L WAS OPEN: RVR WAS RPTED TO US BY GND CTL AT RVR 3500. RWY 9R WAS CLOSED WITH SNOWPLOWS ATTEMPTING TO CLR IT. THE CARGO RAMP HAD NOT BEEN PLOWED. THERE WAS 4-6' OF SNOW ON ALL PARTS OF THE CARGO RAMP, WITH NO MARKINGS VISIBLE. THE ONLY LIGHTS VISIBLE WERE TWO GREEN CTRLINE LIGHTS ON TXWY 'Q' AHEAD OF US. MORE IMPORTANTLY, WE REALIZED AFTERWARDS THAT THERE ARE NO EDGE LIGHTS ON THE RAMP. WE TAXIED FORWARD TO WHERE WE BELIEVED WE WOULD BE ABLE TO TURN R ONTO TXWY 'Q' ON OUR WAY TO RWY 9L. AFTER A SHORT TAXI WE SAW GRASS STICKING OUT OF THE SNOW ABOUT 25' AHEAD OF US. WE ATTEMPTED TO TURN L TO STAY ON WHAT WE BELIEVED WAS THE RAMP. HOWEVER, WE HAD ALREADY TAXIED OFF OF THE PREPARED SURFACE BUT DID NOT REALIZE IT. WE WERE NOTIFIED WE WERE IN THE GRASS BY GND PERSONNEL WHO CAME UP TO THE ACFT AND TOLD US THROUGH INTERCOM. THE ACFT WAS SHUT DOWN AFTER NOTIFYING GND CTL. I BELIEVE THIS OCCURRED BECAUSE THE ENTIRE RAMP WAS OBSCURED UNDER SNOW AND THAT NO CLR MARKINGS OR EDGE LIGHTS ARE PRESENT ON THE CARGO RAMP. THERE NEEDS TO BE SOME LIGHTING DEMARKING THE EDGE OF THE PREPARED SURFACE. ALSO, KEEPING THE CARGO RAMP PLOWED WOULD HAVE GREATLY ASSISTED IN IDENTING WHERE THE PAVEMENT ENDED. PLOWING ON THE CARGO RAMP DID NOT START UNTIL AFTER OUR ACFT BECAME STUCK. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. RPTR STATES THERE WAS A BLIZZARD BEGINNING TO BLOW AND PROBABLY SHOULD HAVE ASKED FOR A 'FOLLOW ME' TRUCK OR JUST STAYED PUT. THERE IS A KIND OF VEH DRIVER AREA AND AS ACFT BEGAN TO TAXI A TRUCK WAS COMING R TOWARD ACFT. CREW MOVED TO R TO ASSURE CLRING THE TRUCK AND COULD NOT DETERMINE THAT THEY WERE SO NEAR THE EDGE. A DAY AND A HALF LATER WHEN ACFT WAS BEING MOVED THERE WERE CTRLINE LIGHTS VISIBLE. THE WERE JUST TOTALLY COVERED AT THE TIME OF EVENT.

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.