Air carrier widebody transport reported to have entered runway for back track without clearance.

Attributes
ACN	93123
Time
Date	198808
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : gig
State Reference	FO
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	Widebody, Low Wing, 4 Turbojet Eng
Navigation In Use	Other
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 : 150 flight time total : 13000
ASRS Report	93123
Person 2
Affiliation	government other
Function	controller : ground
Events
Anomaly	incursion : runway other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

After start-up, first officer called ground control for taxi. Ground control very clearly in english cleared us to runway 09 via back track on runway 15. This was read back exactly by the first officer and we proceeded to taxi via runway 15 back track to runway 09. When 1/2 way down runway 15 ground control told us we had no permission to taxi. I responded yes we did via the previous transmission. The operator became confused as all communications were in portuguese not english. I feel that we understood exactly what ATC said, and that either they forgot, or there was a language/word mistake by the controller. No evasive action was necessary. One aircraft was observed holding on runway 33 prior to our entering the runway for back track.

Original NASA ASRS Text

Title: ACR WDB REPORTED TO HAVE ENTERED RWY FOR BACK TRACK WITHOUT CLRNC.

Narrative: AFTER START-UP, F/O CALLED GND CTL FOR TAXI. GND CTL VERY CLRLY IN ENGLISH CLRED US TO RWY 09 VIA BACK TRACK ON RWY 15. THIS WAS READ BACK EXACTLY BY THE F/O AND WE PROCEEDED TO TAXI VIA RWY 15 BACK TRACK TO RWY 09. WHEN 1/2 WAY DOWN RWY 15 GND CTL TOLD US WE HAD NO PERMISSION TO TAXI. I RESPONDED YES WE DID VIA THE PREVIOUS XMISSION. THE OPERATOR BECAME CONFUSED AS ALL COMS WERE IN PORTUGUESE NOT ENGLISH. I FEEL THAT WE UNDERSTOOD EXACTLY WHAT ATC SAID, AND THAT EITHER THEY FORGOT, OR THERE WAS A LANGUAGE/WORD MISTAKE BY THE CTLR. NO EVASIVE ACTION WAS NECESSARY. ONE ACFT WAS OBSERVED HOLDING ON RWY 33 PRIOR TO OUR ENTERING THE RWY FOR BACK TRACK.

Data retrieved from NASA's ASRS site as of August 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.