Narrative:

Upon reaching number 3 in line for takeoff runway 30; after an approximate 20-minute wait in line with aircraft initially numbering around 20 for departure; a runway incursion involving my aircraft occurred. Both crew members heard the tower control say something to the effect (call sign); able to make the right turn on quebec for an intersection departure zulu; 10;000 ft remaining? The pilot not flying working the radios this particular leg; and looked at me for concurrence; I nodded and verbalized 'of course'; he then acknowledged to the tower controller we could accept the intersection departure. We both heard next 'right turn on quebec; left turn on zulu; for runway 30 intersection zulu departure'. I assumed the tower controller for whatever reason; was taking us in front of the other two aircraft for departure; a seemingly logical conclusion at the time given the taxi instructions to maneuver around the two aircraft in front of us. I called for the before takeoff checklist; turned around and advised the passenger we were cleared onto the runway for departure; and proceeded to taxi as instructed via quebec and zulu for 30; to wait for further takeoff clearance. We were now conducting the challenge response before takeoff checklists and each crewmember respectively turning on appropriate switches; arming spoilers; etc. As I taxied via quebec and zulu. Upon crossing the hold short line I looked left as I always do; and saw the aircraft that was #1 moving into position on the runway now behind us. The first officer asked me as I was crossing the hold short line 'are we going to hold or go into position?' I replied; 'we were cleared onto the runway'; the first officer did not question or challenge me; or the tower controllers instructions any further; so I continued to taxi onto the runway. Once we took position for departure; and were lined up with the centerline waiting takeoff clearance; the tower controller said something to the effect 'that is not what I wanted you to do; exit the runway immediately on yankee; right on quebec; right on zulu; and hold short runway 30.' we then heard him say to the aircraft that pulled onto the runway behind us to cancel takeoff clearance. The tower controller advised us we had not been cleared onto the runway; that the aircraft behind us had been cleared for takeoff; and instructed us to take down a telephone number for possible pilot deviation. The jet on the runway was re-cleared for takeoff; we were subsequently next in sequence and cleared for takeoff. Once at a safe cruise altitude I called the tower supervisor on the cockpit satellite phone. I was very apologetic for our misunderstanding of instructions. He advised me that he listened to the tapes. The supervisor told me that the tower controller did not say 'line-up and wait or cleared for takeoff.' I acknowledged that we (crew) agree and did not hear him say either of those two phrases that the crew confusion came into play as he did not say 'hold short' either. I understand the pilot's responsibility to query ambiguous ATC instructions; that I should have stopped the aircraft and clarified what was expected of us. I told him I was sorry and certainly would never cross a hold short line again unless I specifically heard the terminology 'line up and wait' or 'cleared for takeoff.' the supervisor advised he was filing a pilot deviation.

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Original NASA ASRS Text

Title: LJ60 Captain describes the circumstances leading up to a runway incursion at IAD.

Narrative: Upon reaching number 3 in line for takeoff Runway 30; after an approximate 20-minute wait in line with aircraft initially numbering around 20 for departure; a runway incursion involving my aircraft occurred. Both crew members heard the Tower Control say something to the effect (call sign); able to make the right turn on Quebec for an intersection departure Zulu; 10;000 FT remaining? The pilot not flying working the radios this particular leg; and looked at me for concurrence; I nodded and verbalized 'of course'; he then acknowledged to the Tower Controller we could accept the intersection departure. We both heard next 'right turn on Quebec; left turn on Zulu; for Runway 30 Intersection Zulu departure'. I assumed the Tower Controller for whatever reason; was taking us in front of the other two aircraft for departure; a seemingly logical conclusion at the time given the taxi instructions to maneuver around the two aircraft in front of us. I called for the before takeoff checklist; turned around and advised the passenger we were cleared onto the runway for departure; and proceeded to taxi as instructed via Quebec and Zulu for 30; to wait for further takeoff clearance. We were now conducting the challenge response before takeoff checklists and each crewmember respectively turning on appropriate switches; arming spoilers; etc. as I taxied via Quebec and Zulu. Upon crossing the hold short line I looked left as I always do; and saw the aircraft that was #1 moving into position on the runway now behind us. The First Officer asked me as I was crossing the hold short line 'are we going to hold or go into position?' I replied; 'We were cleared onto the runway'; the First Officer did not question or challenge me; or the Tower Controllers instructions any further; so I continued to taxi onto the runway. Once we took position for departure; and were lined up with the centerline waiting takeoff clearance; the Tower Controller said something to the effect 'that is not what I wanted you to do; exit the runway immediately on Yankee; right on Quebec; right on Zulu; and Hold Short Runway 30.' We then heard him say to the aircraft that pulled onto the runway behind us to cancel takeoff clearance. The Tower Controller advised us we had not been cleared onto the runway; that the aircraft behind us had been cleared for takeoff; and instructed us to take down a telephone number for possible pilot deviation. The jet on the runway was re-cleared for takeoff; we were subsequently next in sequence and cleared for takeoff. Once at a safe cruise altitude I called the Tower Supervisor on the cockpit satellite phone. I was very apologetic for our misunderstanding of instructions. He advised me that he listened to the tapes. The Supervisor told me that the Tower Controller did not say 'line-up and wait or cleared for takeoff.' I acknowledged that we (crew) agree and did not hear him say either of those two phrases that the crew confusion came into play as he did not say 'hold short' either. I understand the pilot's responsibility to query ambiguous ATC instructions; that I should have stopped the aircraft and clarified what was expected of us. I told him I was sorry and certainly would never cross a hold short line again unless I specifically heard the terminology 'line up and wait' or 'cleared for takeoff.' The Supervisor advised he was filing a pilot deviation.

Data retrieved from NASA's ASRS site as of April 2012 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.