Distracted by Tower

Distracted by a Tower request to adjust the transponder, the Captain of a Cessna Citation with 23000 hours (1800 hours in type) crosses the active runway at Houston Hobby (KHOU) without a clearance.

We were taxiing out for takeoff and were cleared to taxi from the FBO to Runway 4 at HOU. As we approached Runway 4, Ground Control called us to ask us to turn our squawk on. I looked over and we were already squawking the proper numbers on both transponders. Rather than let the First Officer handle his job (which he was very capable of doing), I became distracted and taxied across the approach end of Runway 4 to get in line behind a commuter jet holding short of another runway, I believe Runway 35. Of course, my mind was telling me he was holding short of Runway 4 and we were going to follow him. Fortunately, there was no other traffic on the approach to Runway 4 and, therefore, no conflicts with anyone else. This is 'proof positive' that no matter how many hours/years of experience one has, if you lose your concentration for only a moment, it could certainly turn out much worse than this -- a valuable lesson learned by a very experienced pilot. Also, I might add, a very lucky one! This was discovered by Hobby Tower, they told us that we had crossed Runway 4 and to do a 180 degree turn and cleared us for takeoff from the other side. Since there was no conflict -- no harm/no foul, but it is my duty to report this because if this report were to help prevent just one conflict/accident, then it is certainly worth my time.

Report from the Aviation Safety Reporting System (ACN: 818328).