B727-200 misinterpreted airport diagram and crossed runway 4L without clearance. No conflict.

Attributes
ACN	346371
Time
Date	199608
Day	Sat
Local Time Of Day	0601 To 1200
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
Controlling Facilities	tower : gyy
Operator	common carrier : air carrier
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Flight Phase	ground other : taxi
Flight Plan	IFR
Aircraft 2
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : commercial pilot : cfi pilot : atp pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 11800 flight time type : 5000
ASRS Report	346371
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 120 flight time total : 14000 flight time type : 5000
ASRS Report	346382
Events
Anomaly	incursion : runway non adherence : clearance
Independent Detector	other controllera 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

Narrative:

Pushed back from gate facing west. Ground control cleared us to 'runway 9L via txwys a, G, B, J.' began taxi with left turn onto taxiway a and right onto taxiway G. Looking at the airport diagram, I saw taxiway identifier B overlapping the runway 9L parallel taxiway and thought taxiway B was the parallel. Also passing in front of us from right to left was an air carrier taxiing on the parallel (taxiway H) and across runway 4L on his way to taxiway J and runway 9L. Having misinterpreted the diagram and seeing the air carrier going the same route I had mentally perceived to be correct, I followed the air carrier across runway 4L on taxiway H. Ground control did not catch the error until we were already on runway 4L. To prevent this type of mistake, I would suggest that commercial chart change their method of labeling airport diagrams by: 1) do not place a letter identifier such that it touches more than 1 taxiway, 2) for the O'hare diagram, mark taxiway B with more B's, and 3) very importantly, if a taxiway is curved, the letter identifier should be perpendicular to the curve to make taxiway identify more positive. Supplemental information from acn 346382: company and commercial key personnel are being contacted with suggestion for fix.

Original NASA ASRS Text

Title: B727-200 MISINTERPRETED ARPT DIAGRAM AND CROSSED RWY 4L WITHOUT CLRNC. NO CONFLICT.

Narrative: PUSHED BACK FROM GATE FACING W. GND CTL CLRED US TO 'RWY 9L VIA TXWYS A, G, B, J.' BEGAN TAXI WITH L TURN ONTO TXWY A AND RIGHT ONTO TXWY G. LOOKING AT THE ARPT DIAGRAM, I SAW TXWY IDENTIFIER B OVERLAPPING THE RWY 9L PARALLEL TXWY AND THOUGHT TXWY B WAS THE PARALLEL. ALSO PASSING IN FRONT OF US FROM R TO L WAS AN ACR TAXIING ON THE PARALLEL (TXWY H) AND ACROSS RWY 4L ON HIS WAY TO TXWY J AND RWY 9L. HAVING MISINTERPRETED THE DIAGRAM AND SEEING THE ACR GOING THE SAME RTE I HAD MENTALLY PERCEIVED TO BE CORRECT, I FOLLOWED THE ACR ACROSS RWY 4L ON TXWY H. GND CTL DID NOT CATCH THE ERROR UNTIL WE WERE ALREADY ON RWY 4L. TO PREVENT THIS TYPE OF MISTAKE, I WOULD SUGGEST THAT COMMERCIAL CHART CHANGE THEIR METHOD OF LABELING ARPT DIAGRAMS BY: 1) DO NOT PLACE A LETTER IDENTIFIER SUCH THAT IT TOUCHES MORE THAN 1 TXWY, 2) FOR THE O'HARE DIAGRAM, MARK TXWY B WITH MORE B'S, AND 3) VERY IMPORTANTLY, IF A TXWY IS CURVED, THE LETTER IDENTIFIER SHOULD BE PERPENDICULAR TO THE CURVE TO MAKE TXWY IDENT MORE POSITIVE. SUPPLEMENTAL INFO FROM ACN 346382: COMPANY AND COMMERCIAL KEY PERSONNEL ARE BEING CONTACTED WITH SUGGESTION FOR FIX.

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.