Narrative:

While taxiing to hold short of active runway, PF (myself) and 2ND pilot were watching WX conditions steadily worsen although still VFR. Did runup check using standard C172 preflight sheet which was not as comprehensive as my own personal set of preflight instructions. Ground control was issuing advisories to us indicating WX conditions that appeared better than what they appeared to me. I then asked copilot (more experienced and IFR rated) to take over and do the takeoff, but he thought, and I concurred, that WX was still better than what ground control was dispensing. While my mind was still absorbed with this WX scenario, I was asked by ground control if I was still going to depart into lowering conditions and I replied that I was. He replied 'roger' and at that point I mistakenly taxied onto the active runway without being cleared to do so. I immediately realized my mistake and told tower that I was on the runway awaiting takeoff. He stated I wasn't cleared to take the active and then he did clear me to takeoff. I apologized for the transgression and took off, returning soon thereafter because I did not like the WX scenario. Being a super safety conscientious pilot, I was terribly angered at my performance and embarrassed also. Due to having more of my attention outside the plane than on the inside, thereby taking my concentration off a proper, step-by-step preflight. I did not go through each item because I was busier scanning the clouds than the preflight checklist. In the future, I will be religiously attentive to paying more attention to details as I have been taught and if this situation happens again, I will not divide my attention, thereby preventing the mental confusion I just experienced.

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Original NASA ASRS Text

Title: SMA PLT TAXIES INTO POS AND HOLD WITHOUT CLRNC.

Narrative: WHILE TAXIING TO HOLD SHORT OF ACTIVE RWY, PF (MYSELF) AND 2ND PLT WERE WATCHING WX CONDITIONS STEADILY WORSEN ALTHOUGH STILL VFR. DID RUNUP CHK USING STANDARD C172 PREFLT SHEET WHICH WAS NOT AS COMPREHENSIVE AS MY OWN PERSONAL SET OF PREFLT INSTRUCTIONS. GND CTL WAS ISSUING ADVISORIES TO US INDICATING WX CONDITIONS THAT APPEARED BETTER THAN WHAT THEY APPEARED TO ME. I THEN ASKED COPLT (MORE EXPERIENCED AND IFR RATED) TO TAKE OVER AND DO THE TKOF, BUT HE THOUGHT, AND I CONCURRED, THAT WX WAS STILL BETTER THAN WHAT GND CTL WAS DISPENSING. WHILE MY MIND WAS STILL ABSORBED WITH THIS WX SCENARIO, I WAS ASKED BY GND CTL IF I WAS STILL GOING TO DEPART INTO LOWERING CONDITIONS AND I REPLIED THAT I WAS. HE REPLIED 'ROGER' AND AT THAT POINT I MISTAKENLY TAXIED ONTO THE ACTIVE RWY WITHOUT BEING CLRED TO DO SO. I IMMEDIATELY REALIZED MY MISTAKE AND TOLD TWR THAT I WAS ON THE RWY AWAITING TKOF. HE STATED I WASN'T CLRED TO TAKE THE ACTIVE AND THEN HE DID CLR ME TO TKOF. I APOLOGIZED FOR THE TRANSGRESSION AND TOOK OFF, RETURNING SOON THEREAFTER BECAUSE I DID NOT LIKE THE WX SCENARIO. BEING A SUPER SAFETY CONSCIENTIOUS PLT, I WAS TERRIBLY ANGERED AT MY PERFORMANCE AND EMBARRASSED ALSO. DUE TO HAVING MORE OF MY ATTN OUTSIDE THE PLANE THAN ON THE INSIDE, THEREBY TAKING MY CONCENTRATION OFF A PROPER, STEP-BY-STEP PREFLT. I DID NOT GO THROUGH EACH ITEM BECAUSE I WAS BUSIER SCANNING THE CLOUDS THAN THE PREFLT CHKLIST. IN THE FUTURE, I WILL BE RELIGIOUSLY ATTENTIVE TO PAYING MORE ATTN TO DETAILS AS I HAVE BEEN TAUGHT AND IF THIS SIT HAPPENS AGAIN, I WILL NOT DIVIDE MY ATTN, THEREBY PREVENTING THE MENTAL CONFUSION I JUST EXPERIENCED.

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.