Aircraft taxied near runway which caused tower to cancel another aircraft's takeoff clearance.

Attributes
ACN	431350
Time
Date	199903
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : mdw.airport
State Reference	IL
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	ground : taxi
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tower : mdw.tower
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	ground : takeoff roll
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 6000 flight time type : 2500
ASRS Report	431350
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine pilot : atp pilot : cfi
Experience	flight time last 90 days : 38 flight time total : 5800 flight time type : 38
ASRS Report	431714
Events
Anomaly	non adherence : clearance
Independent Detector	other controllera other controllerb other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance controller : issued advisory flight crew : rejected takeoff
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Pushed out of gate at mdw. Started engines and called ready to taxi. Landing and departing runways 31. Taxi instructions were given to taxi: taxiway P, taxiway G short of runway 31R. I had looked at the 10-9 page and it appeared that the ramp area was taxiway Y, and I saw taxiway P to the north. As we taxied straight ahead, I saw taxiway P, which seemed to go more straight ahead rather than making a sharp right turn as it appears on the 10-9 page. From our clearance I assumed it was ok to cross all other runways and hold short of runway 31. So while I was taxiing I started to go on taxiway P straight ahead and was looking across runway 22L for a taxiway G. All about the same instant when I realized there wasn't a taxiway G across the way, I cleared left and right and saw an aircraft with its lights on and the runway 22L runway sign and started to stop. At the same time, mdw ground said 'air carrier X stop.' during this time I believe the aircraft on runway 22L had just started his takeoff roll and was told to stop by the tower. We were still on ground control and we didn't hear anything said on tower frequency. I was also surprised an aircraft was departing on runway 22L. We taxied to runway 31C and took off. I called back to mdw in-flight and talked to a supervisor and apologized for the problem and assured him we were well short of runway 22L. He said he was happy the system worked and everything was fine and he felt there was no runway incursion.

Original NASA ASRS Text

Title: ACFT TAXIED NEAR RWY WHICH CAUSED TWR TO CANCEL ANOTHER ACFT'S TKOF CLRNC.

Narrative: PUSHED OUT OF GATE AT MDW. STARTED ENGS AND CALLED READY TO TAXI. LNDG AND DEPARTING RWYS 31. TAXI INSTRUCTIONS WERE GIVEN TO TAXI: TXWY P, TXWY G SHORT OF RWY 31R. I HAD LOOKED AT THE 10-9 PAGE AND IT APPEARED THAT THE RAMP AREA WAS TXWY Y, AND I SAW TXWY P TO THE N. AS WE TAXIED STRAIGHT AHEAD, I SAW TXWY P, WHICH SEEMED TO GO MORE STRAIGHT AHEAD RATHER THAN MAKING A SHARP R TURN AS IT APPEARS ON THE 10-9 PAGE. FROM OUR CLRNC I ASSUMED IT WAS OK TO CROSS ALL OTHER RWYS AND HOLD SHORT OF RWY 31. SO WHILE I WAS TAXIING I STARTED TO GO ON TXWY P STRAIGHT AHEAD AND WAS LOOKING ACROSS RWY 22L FOR A TXWY G. ALL ABOUT THE SAME INSTANT WHEN I REALIZED THERE WASN'T A TXWY G ACROSS THE WAY, I CLRED L AND R AND SAW AN ACFT WITH ITS LIGHTS ON AND THE RWY 22L RWY SIGN AND STARTED TO STOP. AT THE SAME TIME, MDW GND SAID 'ACR X STOP.' DURING THIS TIME I BELIEVE THE ACFT ON RWY 22L HAD JUST STARTED HIS TKOF ROLL AND WAS TOLD TO STOP BY THE TWR. WE WERE STILL ON GND CTL AND WE DIDN'T HEAR ANYTHING SAID ON TWR FREQ. I WAS ALSO SURPRISED AN ACFT WAS DEPARTING ON RWY 22L. WE TAXIED TO RWY 31C AND TOOK OFF. I CALLED BACK TO MDW INFLT AND TALKED TO A SUPVR AND APOLOGIZED FOR THE PROB AND ASSURED HIM WE WERE WELL SHORT OF RWY 22L. HE SAID HE WAS HAPPY THE SYS WORKED AND EVERYTHING WAS FINE AND HE FELT THERE WAS NO RWY INCURSION.

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.