A B737 flight crew crossed a runway without clearance at yum. Reported non standard signage taxiway ...

Attributes
ACN	444400
Time
Date	199907
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : yum.airport
State Reference	AZ
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	ground : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : private pilot : atp pilot : instrument
Experience	flight time last 90 days : 240 flight time total : 4600 flight time type : 1000
ASRS Report	444400
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	incursion : runway non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance none taken : detected after the fact
Supplementary
Problem Areas	Flight Crew Human Performance Airport
Primary Problem	Airport
Air Traffic Incident	Pilot Deviation

Narrative:

We received taxi clearance from the commuter air terminal eastbound on 'present taxiway to runway 21L, cross the extended centerline of runway 21R.' (airfield diagram depicted taxiway A1 proceeding to and crossing runway 21L and runway 21R not intersecting A1.) we both mistook the overrun of runway 21L ahead as part of taxiway A1 and thus the extended centerline of runway 21R. Our first clue that we had entered the runway 21L overrun was when ground stated 'turn there if able, otherwise continue across runway 21L.' the airfield diagram clearly indicated the threshold of runway 21R stopping short of taxiway A1, but was not so obvious at ground level. Also, since the terminal was not clearly idented on the diagram, we mistook our position on taxiway A1 as being further away from runway 21L than we were. Compounding signage at taxiway A1/runway 21L was nonstandard. The airfield diagram and/or signage are difficult to interpretation.

Original NASA ASRS Text

Title: A B737 FLC CROSSED A RWY WITHOUT CLRNC AT YUM. RPTED NON STANDARD SIGNAGE TXWY A1 AND RWY 27L.

Narrative: WE RECEIVED TAXI CLRNC FROM THE COMMUTER AIR TERMINAL EBOUND ON 'PRESENT TXWY TO RWY 21L, CROSS THE EXTENDED CTRLINE OF RWY 21R.' (AIRFIELD DIAGRAM DEPICTED TXWY A1 PROCEEDING TO AND XING RWY 21L AND RWY 21R NOT INTERSECTING A1.) WE BOTH MISTOOK THE OVERRUN OF RWY 21L AHEAD AS PART OF TXWY A1 AND THUS THE EXTENDED CTRLINE OF RWY 21R. OUR FIRST CLUE THAT WE HAD ENTERED THE RWY 21L OVERRUN WAS WHEN GND STATED 'TURN THERE IF ABLE, OTHERWISE CONTINUE ACROSS RWY 21L.' THE AIRFIELD DIAGRAM CLRLY INDICATED THE THRESHOLD OF RWY 21R STOPPING SHORT OF TXWY A1, BUT WAS NOT SO OBVIOUS AT GND LEVEL. ALSO, SINCE THE TERMINAL WAS NOT CLRLY IDENTED ON THE DIAGRAM, WE MISTOOK OUR POS ON TXWY A1 AS BEING FURTHER AWAY FROM RWY 21L THAN WE WERE. COMPOUNDING SIGNAGE AT TXWY A1/RWY 21L WAS NONSTANDARD. THE AIRFIELD DIAGRAM AND/OR SIGNAGE ARE DIFFICULT TO INTERP.

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.

A B737 flight crew crossed a runway without clearance at yum. Reported non standard signage taxiway A1 and runway 27L.