Narrative:

The fog was moving in toward the airport from the west. My student and I departed runway 29. I underestimated how close and low the fog was. My initial judgement was that if we even reached the fog during climb out, we would be able to go underneath the parts closest to the runway and depart the area. After takeoff it became apparent that the fog was much closer than I thought, and was too low to allow us to pass beneath it. So I continued our climb to get above it. We did not penetrate the clouds but we were unable to maintain VFR (1000 ft above, 2000 ft horizontal). Did I end the flight at this point? No, I continued to the practice area (which was VFR) believing that I would keep an eye on the airport and planned to return if the fog continued to cover it. When we decided to return to the airport, ATIS reported 500 ft broken. We requested a special VFR and returned to the airport without any problem. In this area, some days the fog will move in toward the airport, stop 5 mi away and never come any closer. Some days we go from VFR to IFR in less than 30 mins (this flight was 1 hour in length). I have canceled many lessons because the fog was close and 'could possibly' come in, then it never did. I think, I felt I have been overly cautious in the past, now I know I was being smart. I am not god and there is no way I can second guess what the fog is going to do. In addition, I should have discontinued the flight immediately after I realized how close the fog was. I just refused to believe it would move in so quickly. I discussed with my student all of my errors in judgement, and the fact that I will not make the same mistake again. Hopefully, my student will learn from my errors, and not my example.

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Original NASA ASRS Text

Title: INSTRUCTOR WITH STUDENT PLT DEPARTS WITH FOG MOVING INTO AREA. MUST REQUEST SVFR TO RETURN AT END OF TRAINING PERIOD.

Narrative: THE FOG WAS MOVING IN TOWARD THE ARPT FROM THE W. MY STUDENT AND I DEPARTED RWY 29. I UNDERESTIMATED HOW CLOSE AND LOW THE FOG WAS. MY INITIAL JUDGEMENT WAS THAT IF WE EVEN REACHED THE FOG DURING CLBOUT, WE WOULD BE ABLE TO GO UNDERNEATH THE PARTS CLOSEST TO THE RWY AND DEPART THE AREA. AFTER TKOF IT BECAME APPARENT THAT THE FOG WAS MUCH CLOSER THAN I THOUGHT, AND WAS TOO LOW TO ALLOW US TO PASS BENEATH IT. SO I CONTINUED OUR CLB TO GET ABOVE IT. WE DID NOT PENETRATE THE CLOUDS BUT WE WERE UNABLE TO MAINTAIN VFR (1000 FT ABOVE, 2000 FT HORIZ). DID I END THE FLT AT THIS POINT? NO, I CONTINUED TO THE PRACTICE AREA (WHICH WAS VFR) BELIEVING THAT I WOULD KEEP AN EYE ON THE ARPT AND PLANNED TO RETURN IF THE FOG CONTINUED TO COVER IT. WHEN WE DECIDED TO RETURN TO THE ARPT, ATIS RPTED 500 FT BROKEN. WE REQUESTED A SPECIAL VFR AND RETURNED TO THE ARPT WITHOUT ANY PROB. IN THIS AREA, SOME DAYS THE FOG WILL MOVE IN TOWARD THE ARPT, STOP 5 MI AWAY AND NEVER COME ANY CLOSER. SOME DAYS WE GO FROM VFR TO IFR IN LESS THAN 30 MINS (THIS FLT WAS 1 HR IN LENGTH). I HAVE CANCELED MANY LESSONS BECAUSE THE FOG WAS CLOSE AND 'COULD POSSIBLY' COME IN, THEN IT NEVER DID. I THINK, I FELT I HAVE BEEN OVERLY CAUTIOUS IN THE PAST, NOW I KNOW I WAS BEING SMART. I AM NOT GOD AND THERE IS NO WAY I CAN SECOND GUESS WHAT THE FOG IS GOING TO DO. IN ADDITION, I SHOULD HAVE DISCONTINUED THE FLT IMMEDIATELY AFTER I REALIZED HOW CLOSE THE FOG WAS. I JUST REFUSED TO BELIEVE IT WOULD MOVE IN SO QUICKLY. I DISCUSSED WITH MY STUDENT ALL OF MY ERRORS IN JUDGEMENT, AND THE FACT THAT I WILL NOT MAKE THE SAME MISTAKE AGAIN. HOPEFULLY, MY STUDENT WILL LEARN FROM MY ERRORS, AND NOT MY EXAMPLE.

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.