Narrative:

Holding for departure at bfi runway 31L intersection A10. Called tower for takeoff clearance with straight-out northwest departure. Tower responded; 'roger.' this irritated me as had been happening recently at bfi; including while I was calling in ready for takeoff at hot spot at runway 13R intersection A9. (Jo 7110.65U does not describe this terminology in this situation; there is no possible read back and a student/inexperienced pilot may mistake 'roger' for 'affirmative' and incorrectly believe they have been cleared for takeoff and proceed to commit a runway incursion. I had very recently reported this to the regional faast team and received a voicemail that they agreed that they had forwarded my mail to ATC qc.) over the next approximately 10 minutes; we waited for takeoff clearance. Eventually a heavy jet called in on ILS runway 31L at duane OM and was cleared to land. I couldn't understand why we weren't cleared for takeoff in the interim as it took a few minutes for the jet to approach and land. As I stewed about the 'roger' response and apparently being ignored for takeoff; a C172 with a student pilot reported inbound from the west and was told to 'report the reservoir' as a citation X then called in on the ILS runway 31L at duane. I could see another of what I considered an unnecessary delay to sequence in these two aircraft in front of us. I was then distracted for a couple of minutes apologizing to my students at the delay and using it as a teachable moment to discuss proper ATC procedures. I consequently lost situational awareness. I then looked over to see the cessna touch down on runway 31L and began decelerating to make the turn off at A10. At that point; I distinctly heard the tower clear my aircraft for takeoff. In my frustrated state; I immediately went lights/camera/action and taxied across the hold short line. As I did so three things happened simultaneously 1) it was clear that the landing cessna was not going to make the wide A10 turnoff without a back taxi; which was going to put me in conflict with him. 2) the citation X that I had lost situational awareness of flew over the cessna at about 100 ft; spooling up and pitching up in obvious go-around mode. 3) the tower cancelled my takeoff clearance with an apology about confusing n-numbers. I had only moved about two plane lengths past the hold short line and was able to pivot about and quickly get off the runway. This incident in retrospect was essentially about a runway conflict between the other cessna and the citation X. Nevertheless I had ended up involved making a runway incursion in a situation where I could have been involved in a rare [3-way] runway collision. I also wonder how the tower controller could have not only confused my n-number with the landing cessna's but also actually cleared me for the takeoff. In terms of human performance consideration; clearly allowing myself to get worked up over the controller's actions contributed to my loss of situational awareness; in particular forgetting that there was a citation on final. I have taught my students that they have to be vigilant like a laser beam at that taxiway-runway interface to avoid incursions and to not enter the runway unless they perfectly understand they've been cleared to do so. Yet; I ended up becoming distracted; losing track of a landing airplane and hearing my n-number but possibly not the takeoff clearance I thought I heard and subsequently committing a runway incursion. Another factor that I stress in operating at bfi is that it has a high operational tempo with a mix of traffic up to heavy jets. As a result; I teach to be ready for takeoff when calling the tower for clearance immediately turning on the landing light; setting the transponder for 'C' and then taxiing onto the runway and taking off. I point out that sitting there for even ten or fifteen seconds before taxiing onto the runway is bad form; and could disrupt traffic flow and result in a canceled takeoff clearance. In view of my experience; I'm going to now also stress a situational awareness check at the front end including carefully listening in on tower frequency for enough time to understand the traffic flow into and off your runway.

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Original NASA ASRS Text

Title: C172 Instructor pilot describes a possible runway incursion at BFI after becoming distracted due to an unnecessary delay initiated by the Tower.

Narrative: Holding for departure at BFI Runway 31L intersection A10. Called Tower for takeoff clearance with straight-out northwest departure. Tower responded; 'Roger.' This irritated me as had been happening recently at BFI; including while I was calling in ready for takeoff at hot spot at Runway 13R intersection A9. (JO 7110.65U does not describe this terminology in this situation; there is no possible read back and a student/inexperienced pilot may mistake 'Roger' for 'Affirmative' and incorrectly believe they have been cleared for takeoff and proceed to commit a runway incursion. I had very recently reported this to the regional FAAST Team and received a voicemail that they agreed that they had forwarded my mail to ATC QC.) Over the next approximately 10 minutes; we waited for takeoff clearance. Eventually a heavy jet called in on ILS Runway 31L at DUANE OM and was cleared to land. I couldn't understand why we weren't cleared for takeoff in the interim as it took a few minutes for the jet to approach and land. As I stewed about the 'Roger' response and apparently being ignored for takeoff; a C172 with a student pilot reported inbound from the west and was told to 'report the reservoir' as a Citation X then called in on the ILS Runway 31L at DUANE. I could see another of what I considered an unnecessary delay to sequence in these two aircraft in front of us. I was then distracted for a couple of minutes apologizing to my students at the delay and using it as a teachable moment to discuss proper ATC procedures. I consequently lost situational awareness. I then looked over to see the Cessna touch down on Runway 31L and began decelerating to make the turn off at A10. At that point; I distinctly heard the Tower clear my aircraft for takeoff. In my frustrated state; I immediately went lights/camera/action and taxied across the hold short line. As I did so three things happened simultaneously 1) It was clear that the landing Cessna was not going to make the wide A10 turnoff without a back taxi; which was going to put me in conflict with him. 2) The Citation X that I had lost situational awareness of flew over the Cessna at about 100 FT; spooling up and pitching up in obvious go-around mode. 3) The Tower cancelled my takeoff clearance with an apology about confusing N-numbers. I had only moved about two plane lengths past the hold short line and was able to pivot about and quickly get off the runway. This incident in retrospect was essentially about a runway conflict between the other Cessna and the Citation X. Nevertheless I had ended up involved making a runway incursion in a situation where I could have been involved in a rare [3-way] runway collision. I also wonder how the Tower Controller could have not only confused my N-number with the landing Cessna's but also actually cleared me for the takeoff. In terms of human performance consideration; clearly allowing myself to get worked up over the Controller's actions contributed to my loss of situational awareness; in particular forgetting that there was a Citation on final. I have taught my students that they have to be vigilant like a laser beam at that taxiway-runway interface to avoid incursions and to not enter the runway unless they perfectly understand they've been cleared to do so. Yet; I ended up becoming distracted; losing track of a landing airplane and hearing my N-number but possibly not the takeoff clearance I thought I heard and subsequently committing a runway incursion. Another factor that I stress in operating at BFI is that it has a high operational tempo with a mix of traffic up to heavy jets. As a result; I teach to be ready for takeoff when calling the Tower for clearance immediately turning on the landing light; setting the transponder for 'C' and then taxiing onto the runway and taking off. I point out that sitting there for even ten or fifteen seconds before taxiing onto the runway is bad form; and could disrupt traffic flow and result in a canceled takeoff clearance. In view of my experience; I'm going to now also stress a Situational Awareness check at the front end including carefully listening in on Tower frequency for enough time to understand the traffic flow into and off your runway.

Data retrieved from NASA's ASRS site as of July 2013 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.