Narrative:

Ground control issued 'wait for XXX plane, then taxi to runway 25.' I misunderstood as 'taxi onto runway 25.' how could I possibly have misinterped the instruction so badly? Here are the facts: 1) ATIS told that runway 29 was in use for approach. The day before, we had landed on that runway and saw a number of planes take off on runway 29 as well. 2) an XXX plane had taxied in on runway 25. It was the second XXX plane to do so during the past 10 mins. Given these facts, I assumed that runway 25 was used as taxiway for traffic that had landed on runway 29, and that it was also used for taxiing to runway 29. So mentally I was prepared to taxi to runway 29. This misinterpretation would not have caused a problem if I had read back the instruction. But it seemed all so clear to me that I just acknowledged the instruction and taxied onto runway 25. The controller pointed out the error and had me continue the taxiing for takeoff on runway 29. Lesson learned: even if an instruction seems absolutely clear, I must read it back to confirm that I have correctly interpreted it. This mistake occurred during a 2-WK trip where I took off and landed at a number of airports. After the incident, I made it a rule to read back every instruction. It worked extremely well. Indeed, I discovered that the controllers liked my reading back the instructions. And I had assumed that this was somewhat annoying to them since it blocked the frequency! Note: before the trip, a pilot group magazine had a long article about runway incursions. I studied all the material carefully, and worked through the booklet that was glued into the pilot magazine. This was most helpful. However, I did not follow the advice that each instruction should be read back. I just assumed that, when it was perfectly clear, a readback was not needed. As I learned on the trip, every instruction must be read back, no exception allowed.

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Original NASA ASRS Text

Title: PLT IN EXPERIMENTAL ACFT AT MSO TAXIES ONTO AN ACTIVE RWY, ALTHOUGH THE CTLR HAD INSTRUCTED THE PLT, 'TAXI TO RWY....'

Narrative: GND CTL ISSUED 'WAIT FOR XXX PLANE, THEN TAXI TO RWY 25.' I MISUNDERSTOOD AS 'TAXI ONTO RWY 25.' HOW COULD I POSSIBLY HAVE MISINTERPED THE INSTRUCTION SO BADLY? HERE ARE THE FACTS: 1) ATIS TOLD THAT RWY 29 WAS IN USE FOR APCH. THE DAY BEFORE, WE HAD LANDED ON THAT RWY AND SAW A NUMBER OF PLANES TAKE OFF ON RWY 29 AS WELL. 2) AN XXX PLANE HAD TAXIED IN ON RWY 25. IT WAS THE SECOND XXX PLANE TO DO SO DURING THE PAST 10 MINS. GIVEN THESE FACTS, I ASSUMED THAT RWY 25 WAS USED AS TXWY FOR TFC THAT HAD LANDED ON RWY 29, AND THAT IT WAS ALSO USED FOR TAXIING TO RWY 29. SO MENTALLY I WAS PREPARED TO TAXI TO RWY 29. THIS MISINTERPRETATION WOULD NOT HAVE CAUSED A PROB IF I HAD READ BACK THE INSTRUCTION. BUT IT SEEMED ALL SO CLR TO ME THAT I JUST ACKNOWLEDGED THE INSTRUCTION AND TAXIED ONTO RWY 25. THE CTLR POINTED OUT THE ERROR AND HAD ME CONTINUE THE TAXIING FOR TKOF ON RWY 29. LESSON LEARNED: EVEN IF AN INSTRUCTION SEEMS ABSOLUTELY CLR, I MUST READ IT BACK TO CONFIRM THAT I HAVE CORRECTLY INTERPED IT. THIS MISTAKE OCCURRED DURING A 2-WK TRIP WHERE I TOOK OFF AND LANDED AT A NUMBER OF ARPTS. AFTER THE INCIDENT, I MADE IT A RULE TO READ BACK EVERY INSTRUCTION. IT WORKED EXTREMELY WELL. INDEED, I DISCOVERED THAT THE CTLRS LIKED MY READING BACK THE INSTRUCTIONS. AND I HAD ASSUMED THAT THIS WAS SOMEWHAT ANNOYING TO THEM SINCE IT BLOCKED THE FREQ! NOTE: BEFORE THE TRIP, A PLT GROUP MAGAZINE HAD A LONG ARTICLE ABOUT RWY INCURSIONS. I STUDIED ALL THE MATERIAL CAREFULLY, AND WORKED THROUGH THE BOOKLET THAT WAS GLUED INTO THE PLT MAGAZINE. THIS WAS MOST HELPFUL. HOWEVER, I DID NOT FOLLOW THE ADVICE THAT EACH INSTRUCTION SHOULD BE READ BACK. I JUST ASSUMED THAT, WHEN IT WAS PERFECTLY CLR, A READBACK WAS NOT NEEDED. AS I LEARNED ON THE TRIP, EVERY INSTRUCTION MUST BE READ BACK, NO EXCEPTION ALLOWED.

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.