Clearance misunderstanding resulting in a runway incursion in bangkok, thailand.

Attributes
ACN	571071
Time
Date	200301
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : vtbd.airport
State Reference	FO
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	ground : 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 : 145 flight time total : 11000 flight time type : 1800
ASRS Report	571071
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : ground less severe incursion : runway non adherence : published procedure
Independent Detector	other controllerb
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance

Narrative:

We were cleared to taxi to runway 21R, but as we taxied, we were told to expect runway 21L. The controller was difficult to understand. As we approached the holding point for runway 21R, we were cleared 'cross runway 21R and line up runway 21L,' which the first officer read back. There was an aircraft on final, but I believed spacing was adequate as we had not stopped at runway 21R. As we crossed the runway, the aircraft on final transmitted, 'we have an aircraft crossing the runway,' and the tower called us and said, 'you were to cross behind the aircraft on final.' the first officer replied, 'that is not what we heard or what we read back.' we lined up on runway 21L, and were cleared to takeoff. The controller, who had issued the clearance to cross the runway, had been hard to understand, and we both assumed that the first officer's readback, when unchallenged, was assurance we had understood the clearance correctly. A more prudent course of action would have been to stop the aircraft and query the controller, especially given the confusion possible due to the use of conditional clrncs in ICAO operations (ie, 'behind the landing aircraft, cross runway 21R and line up runway 21L').

Original NASA ASRS Text

Title: CLRNC MISUNDERSTANDING RESULTING IN A RWY INCURSION IN BANGKOK, THAILAND.

Narrative: WE WERE CLRED TO TAXI TO RWY 21R, BUT AS WE TAXIED, WE WERE TOLD TO EXPECT RWY 21L. THE CTLR WAS DIFFICULT TO UNDERSTAND. AS WE APCHED THE HOLDING POINT FOR RWY 21R, WE WERE CLRED 'CROSS RWY 21R AND LINE UP RWY 21L,' WHICH THE FO READ BACK. THERE WAS AN ACFT ON FINAL, BUT I BELIEVED SPACING WAS ADEQUATE AS WE HAD NOT STOPPED AT RWY 21R. AS WE CROSSED THE RWY, THE ACFT ON FINAL XMITTED, 'WE HAVE AN ACFT XING THE RWY,' AND THE TWR CALLED US AND SAID, 'YOU WERE TO CROSS BEHIND THE ACFT ON FINAL.' THE FO REPLIED, 'THAT IS NOT WHAT WE HEARD OR WHAT WE READ BACK.' WE LINED UP ON RWY 21L, AND WERE CLRED TO TKOF. THE CTLR, WHO HAD ISSUED THE CLRNC TO CROSS THE RWY, HAD BEEN HARD TO UNDERSTAND, AND WE BOTH ASSUMED THAT THE FO'S READBACK, WHEN UNCHALLENGED, WAS ASSURANCE WE HAD UNDERSTOOD THE CLRNC CORRECTLY. A MORE PRUDENT COURSE OF ACTION WOULD HAVE BEEN TO STOP THE ACFT AND QUERY THE CTLR, ESPECIALLY GIVEN THE CONFUSION POSSIBLE DUE TO THE USE OF CONDITIONAL CLRNCS IN ICAO OPS (IE, 'BEHIND THE LNDG ACFT, CROSS RWY 21R AND LINE UP RWY 21L').

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.