Air carrier crosses active runway believing had clearance to do so.

Attributes
ACN	172568
Time
Date	199103
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : phl
State Reference	PA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	ground other : taxi
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	ground : holding
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 120 flight time total : 10000 flight time type : 615
ASRS Report	172568
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 210 flight time total : 14500 flight time type : 2500
ASRS Report	172700
Events
Anomaly	incursion : runway non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : detected after the fact none taken : unable
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

After engines started, called for taxi clearance. Understood cleared to taxi to runway 9R. No specific routing given by ground control. Shortest route to 9R was to cross 9L at taxiway C. Just prior to crossing 9L crew noticed medium large transport in position for takeoff on runway 9L. Aircraft (medium large transport) was not moving. After runway 9L crossing complete ground control asked if we knew that we had just crossed an active runway. We answered yes and said we had been cleared to 9R. Ground control said we had been cleared to 9L and gave us further instructions to taxi to 9R, cancelled it and cleared us to runway 9L (ground control was confused as well). Cockpit crew misunderstood taxi clearance while busy completing checklists and final weight and balance calculations. Perhaps if full taxiing routing given instead of 'taxi to,' misunderstanding would have been avoided.

Original NASA ASRS Text

Title: ACR CROSSES ACTIVE RWY BELIEVING HAD CLRNC TO DO SO.

Narrative: AFTER ENGS STARTED, CALLED FOR TAXI CLRNC. UNDERSTOOD CLRED TO TAXI TO RWY 9R. NO SPECIFIC RTING GIVEN BY GND CTL. SHORTEST RTE TO 9R WAS TO CROSS 9L AT TXWY C. JUST PRIOR TO XING 9L CREW NOTICED MLG IN POS FOR TKOF ON RWY 9L. ACFT (MLG) WAS NOT MOVING. AFTER RWY 9L XING COMPLETE GND CTL ASKED IF WE KNEW THAT WE HAD JUST CROSSED AN ACTIVE RWY. WE ANSWERED YES AND SAID WE HAD BEEN CLRED TO 9R. GND CTL SAID WE HAD BEEN CLRED TO 9L AND GAVE US FURTHER INSTRUCTIONS TO TAXI TO 9R, CANCELLED IT AND CLRED US TO RWY 9L (GND CTL WAS CONFUSED AS WELL). COCKPIT CREW MISUNDERSTOOD TAXI CLRNC WHILE BUSY COMPLETING CHKLISTS AND FINAL WT AND BAL CALCULATIONS. PERHAPS IF FULL TAXIING ROUTING GIVEN INSTEAD OF 'TAXI TO,' MISUNDERSTANDING WOULD HAVE BEEN AVOIDED.

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.