Narrative:

I had been instructed to hold short of runway 25 at taxiway B and was doing so. After several mins of hearing nothing and noticing another aircraft holding position on runway 25, I began to contact ground to remind them I was holding short. At that instant, I was contacted on tower frequency and told (my understanding, which turned out to be wrong) that I was to cross runway 25. As I began to cross, the controller told me to stop and then decided I should continue crossing since I was already onto runway 25. At that point, I was instructed to continue to my assigned runway and to call tower upon my return to the airport. Upon analysis and discussion with the tower the events that led to this incident were: both ground and tower were being monitored in the airplane, but the volume on the radio tuned to ground was too low to hear well and as a result, I missed a ground clearance to cross runway 25. Since I had been cleared to cross runway 25 and did not acknowledge or cross, the controller kept the runway 25 traffic in a position and hold waiting for me to clear. During this time, the controllers tried other frequencys to contact me and finally did so on tower frequency. When I heard the call on tower, I misunderstood it to be a clearance to cross runway 25, then I immediately switched the radio to ground realizing that I should be with them and not tower and acknowledged the crossing instruction. This led to more confusion as the ground controller had not previously heard the tower's transmission to me and so was not expecting any acknowledgement. I realize that this whole incident was my fault and that several mistakes were made. 1) missing the ground clearance to cross runway 25. 2) not clearly understanding the instruction given to me on the tower frequency. 3) switching back to ground too quickly after I had been contacted on the tower frequency. 4) initiating a runway crossing too hastily before I was sure of the instruction. Luckily, the controllers were on the ball and were not going to release the other aircraft until my status had been resolved. This step insured that an accident would be avoided and I am grateful for their professionalism. In the future, I will pay extra attention to where my radios are tuned and verify all instructions/clrncs.

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Original NASA ASRS Text

Title: WHILE HOLDING SHORT OF RWY 25 TO CROSS, THE PLT OF A C172 MISHEARS A XMISSION ON THE TWR FREQ AND WRONGLY BELIEVES HE IS CLRED TO CROSS.

Narrative: I HAD BEEN INSTRUCTED TO HOLD SHORT OF RWY 25 AT TXWY B AND WAS DOING SO. AFTER SEVERAL MINS OF HEARING NOTHING AND NOTICING ANOTHER ACFT HOLDING POS ON RWY 25, I BEGAN TO CONTACT GND TO REMIND THEM I WAS HOLDING SHORT. AT THAT INSTANT, I WAS CONTACTED ON TWR FREQ AND TOLD (MY UNDERSTANDING, WHICH TURNED OUT TO BE WRONG) THAT I WAS TO CROSS RWY 25. AS I BEGAN TO CROSS, THE CTLR TOLD ME TO STOP AND THEN DECIDED I SHOULD CONTINUE XING SINCE I WAS ALREADY ONTO RWY 25. AT THAT POINT, I WAS INSTRUCTED TO CONTINUE TO MY ASSIGNED RWY AND TO CALL TWR UPON MY RETURN TO THE ARPT. UPON ANALYSIS AND DISCUSSION WITH THE TWR THE EVENTS THAT LED TO THIS INCIDENT WERE: BOTH GND AND TWR WERE BEING MONITORED IN THE AIRPLANE, BUT THE VOLUME ON THE RADIO TUNED TO GND WAS TOO LOW TO HEAR WELL AND AS A RESULT, I MISSED A GND CLRNC TO CROSS RWY 25. SINCE I HAD BEEN CLRED TO CROSS RWY 25 AND DID NOT ACKNOWLEDGE OR CROSS, THE CTLR KEPT THE RWY 25 TFC IN A POS AND HOLD WAITING FOR ME TO CLR. DURING THIS TIME, THE CTLRS TRIED OTHER FREQS TO CONTACT ME AND FINALLY DID SO ON TWR FREQ. WHEN I HEARD THE CALL ON TWR, I MISUNDERSTOOD IT TO BE A CLRNC TO CROSS RWY 25, THEN I IMMEDIATELY SWITCHED THE RADIO TO GND REALIZING THAT I SHOULD BE WITH THEM AND NOT TWR AND ACKNOWLEDGED THE XING INSTRUCTION. THIS LED TO MORE CONFUSION AS THE GND CTLR HAD NOT PREVIOUSLY HEARD THE TWR'S XMISSION TO ME AND SO WAS NOT EXPECTING ANY ACKNOWLEDGEMENT. I REALIZE THAT THIS WHOLE INCIDENT WAS MY FAULT AND THAT SEVERAL MISTAKES WERE MADE. 1) MISSING THE GND CLRNC TO CROSS RWY 25. 2) NOT CLRLY UNDERSTANDING THE INSTRUCTION GIVEN TO ME ON THE TWR FREQ. 3) SWITCHING BACK TO GND TOO QUICKLY AFTER I HAD BEEN CONTACTED ON THE TWR FREQ. 4) INITIATING A RWY XING TOO HASTILY BEFORE I WAS SURE OF THE INSTRUCTION. LUCKILY, THE CTLRS WERE ON THE BALL AND WERE NOT GOING TO RELEASE THE OTHER ACFT UNTIL MY STATUS HAD BEEN RESOLVED. THIS STEP INSURED THAT AN ACCIDENT WOULD BE AVOIDED AND I AM GRATEFUL FOR THEIR PROFESSIONALISM. IN THE FUTURE, I WILL PAY EXTRA ATTN TO WHERE MY RADIOS ARE TUNED AND VERIFY ALL INSTRUCTIONS/CLRNCS.

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.