Excursion from taxiway.

Attributes
ACN	218894
Time
Date	199208
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ord
State Reference	IL
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	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	ground other : taxi
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 : 6800 flight time type : 750
ASRS Report	218894
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : commercial pilot : instrument
Experience	flight time last 90 days : 240 flight time total : 5200 flight time type : 3200
ASRS Report	218839
Events
Anomaly	non adherence : clearance other anomaly other anomaly other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation
Situations
ATC Facility	procedure or policy : unspecified
Airport	other physical facility

Narrative:

Taxiing for takeoff, ord-cle. While making a turn on taxiway at ord, right main gear left hard surface and sunk in mud/grass off side of taxiway. Taxi instructions from ord ground were taxi to runway 22L via stub and parallel. Further directions to international ramp later. As we taxied toward runway 22L on the parallel and were about to pass 'branch' crossover taxiway, ground control said turn left at 'branch' to international ramp. I stopped the aircraft, then began a left turn. However, with only the left engine running, the nosewheel began to skid due to the thrust from the left engine and takeoff engine thrust. These actions allowed the aircraft to roll closer to the right side of the 'branch' taxiway. This, in turn, required an even more severe turn and thus more thrust. At this point, the nose tires skidded so far that the right main tires slid off the hard surface into the mud.

Original NASA ASRS Text

Title: EXCURSION FROM TAXIWAY.

Narrative: TAXIING FOR TKOF, ORD-CLE. WHILE MAKING A TURN ON TAXIWAY AT ORD, R MAIN GEAR L HARD SURFACE AND SUNK IN MUD/GRASS OFF SIDE OF TAXIWAY. TAXI INSTRUCTIONS FROM ORD GND WERE TAXI TO RWY 22L VIA STUB AND PARALLEL. FURTHER DIRECTIONS TO INTL RAMP LATER. AS WE TAXIED TOWARD RWY 22L ON THE PARALLEL AND WERE ABOUT TO PASS 'BRANCH' CROSSOVER TAXIWAY, GND CTL SAID TURN L AT 'BRANCH' TO INTL RAMP. I STOPPED THE ACFT, THEN BEGAN A L TURN. HOWEVER, WITH ONLY THE L ENG RUNNING, THE NOSEWHEEL BEGAN TO SKID DUE TO THE THRUST FROM THE L ENG AND TKOF ENG THRUST. THESE ACTIONS ALLOWED THE ACFT TO ROLL CLOSER TO THE R SIDE OF THE 'BRANCH' TAXIWAY. THIS, IN TURN, REQUIRED AN EVEN MORE SEVERE TURN AND THUS MORE THRUST. AT THIS POINT, THE NOSE TIRES SKIDDED SO FAR THAT THE R MAIN TIRES SLID OFF THE HARD SURFACE INTO THE MUD.

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.