Narrative:

I had flown toward ors and climbed up through a low cloud layer to 4;000 ft and was VFR-on-top when I was cleared to cross fegba at or above 3;000; cleared for the ors RNAV (GPS)-a approach. I crossed fegba at 3;000 and turned to a heading of 343 and was on the course line when I began a descent into the airport after crossing fegba; which was reporting 600 ovc. I entered IMC conditions about 2;500 ft and continued my descent toward the FAF nakhu. I neglected to note that I was below the 2;000 ft MDA at nakhu until I was nearly over nakhu; when the GPS flashed a warning that there was terrain ahead. I believe that this happens when an obstruction in the terrain falls within less than 500 vertical ft from the aircraft and I cleared the warning to see where I was on the GPS; since the warning obliterates the navigation screen. It immediately came back on and I noted that not only was I very close to the FAF nakhu; but I was already below the 2;000 ft MDA. At this point I initiated a missed approach; though I believe I had already crossed over nakhu; narrowly missing the obstructing hill that is exactly on the course line and actually seems to be a physical location of the FAF. Once I had climbed back up into VFR-on-top conditions I was able to see the northern edge of the low clouds so I was able to cancel both the IFR clearance and the IFR flight plan and circle around and see the runway; where I landed without incident. I don't know how close we actually came to the terrain; but it had to be very close. Though we never saw it and it was only after landing that I reexamined the approach course and looked at the terrain when the clouds lifted the next day I realized how close we had come to becoming one of the crashes that lists 'controlled flight into terrain after dropping below the MDA' as the cause. I am humbled and very grateful that I am still alive to be able to submit this report. The problem arose from my lack of attention to the MDA as well as my own altitude. I was flying a non-precision approach and was in kind of an automatic 'get down to the MDA' as soon as possible in order to make sure I had the best chance of actually seeing the airport. I hadn't really paid enough attention to the approach plate and the MDA of 2;000 ft at the FAF and was flying as if fegba was the FAF; when it was actually only the IAF. It wasn't until the terrain warnings popped up on the GPS screen that I realized something was wrong with the approach and took corrective action; nearly too late by then since the altitude listed of the terrain is 1;392 ft and I was already nearly 200 ft below that. I would have plowed into the trees had I been any closer before taking corrective action. Fortunately; I had not yet put the gear down and my forward airspeed was such that a small correction in my attitude resulted in an immediate climb; though I'm not exactly sure if the terrain was ahead of me; under me or behind me when I initiated the climb. Certainly if the local altimeter setting was any different than what I had put in my altimeter I could have been either above or below the actually terrain elevation. As I examined this approach I was puzzled as to why they would put the approach path directly over this obstruction. I realize there are constraints given the actual runway heading; but this is a non-precision approach and it looks to me like the approach architects could have placed the final approach course a few degrees east to put it over water and dictated a turn once the approach end if the runway became visible. This would put the final approach course between two obstructions; one on either side; but somehow; that seems somewhat safer than putting it directly over the highest obstruction. Alternatively; they could have designed another approach from the north which lies entirely over water. I realize there are many constraints to putting in IFR approaches and I'm sure this one had any number of restrictions that forced them toput it where they did; but being unaware of the constraints under which the approach architects operate; it isn't immediately obvious to me.

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Original NASA ASRS Text

Title: A single engine pilot on the ORS RNAV GPS-A approach crossed FEGBA at 3;000 FT and began a descent but descended below 2;000 FT prior to the FAF NAKHU and not until the GPS terrain warning alerted did the pilot realize his error in time to execute a missed approach.

Narrative: I had flown toward ORS and climbed up through a low cloud layer to 4;000 FT and was VFR-ON-TOP when I was cleared to cross FEGBA at or above 3;000; cleared for the ORS RNAV (GPS)-A approach. I crossed FEGBA at 3;000 and turned to a heading of 343 and was on the course line when I began a descent into the airport after crossing FEGBA; which was reporting 600 OVC. I entered IMC conditions about 2;500 FT and continued my descent toward the FAF NAKHU. I neglected to note that I was below the 2;000 FT MDA at NAKHU until I was nearly over NAKHU; when the GPS flashed a warning that there was terrain ahead. I believe that this happens when an obstruction in the terrain falls within less than 500 vertical FT from the aircraft and I cleared the warning to see where I was on the GPS; since the warning obliterates the navigation screen. It immediately came back on and I noted that not only was I very close to the FAF NAKHU; but I was already below the 2;000 FT MDA. At this point I initiated a missed approach; though I believe I had already crossed over NAKHU; narrowly missing the obstructing hill that is exactly on the course line and actually seems to be a physical location of the FAF. Once I had climbed back up into VFR-ON-TOP conditions I was able to see the northern edge of the low clouds so I was able to cancel both the IFR clearance and the IFR flight plan and circle around and see the runway; where I landed without incident. I don't know how close we actually came to the terrain; but it had to be very close. Though we never saw it and it was only after landing that I reexamined the approach course and looked at the terrain when the clouds lifted the next day I realized how close we had come to becoming one of the crashes that lists 'controlled flight into terrain after dropping below the MDA' as the cause. I am humbled and very grateful that I am still alive to be able to submit this report. The problem arose from my lack of attention to the MDA as well as my own altitude. I was flying a non-precision approach and was in kind of an automatic 'get down to the MDA' as soon as possible in order to make sure I had the best chance of actually seeing the airport. I hadn't really paid enough attention to the approach plate and the MDA of 2;000 FT at the FAF and was flying as if FEGBA was the FAF; when it was actually only the IAF. It wasn't until the terrain warnings popped up on the GPS screen that I realized something was wrong with the approach and took corrective action; nearly too late by then since the altitude listed of the terrain is 1;392 FT and I was already nearly 200 FT below that. I would have plowed into the trees had I been any closer before taking corrective action. Fortunately; I had not yet put the gear down and my forward airspeed was such that a small correction in my attitude resulted in an immediate climb; though I'm not exactly sure if the terrain was ahead of me; under me or behind me when I initiated the climb. Certainly if the local altimeter setting was any different than what I had put in my altimeter I could have been either above or below the actually terrain elevation. As I examined this approach I was puzzled as to why they would put the approach path directly over this obstruction. I realize there are constraints given the actual runway heading; but this is a non-precision approach and it looks to me like the approach architects could have placed the final approach course a few degrees east to put it over water and dictated a turn once the approach end if the runway became visible. This would put the final approach course between two obstructions; one on either side; but somehow; that seems somewhat safer than putting it directly over the highest obstruction. Alternatively; they could have designed another approach from the north which lies entirely over water. I realize there are many constraints to putting in IFR approaches and I'm sure this one had any number of restrictions that forced them toput it where they did; but being unaware of the constraints under which the approach architects operate; it isn't immediately obvious to me.

Data retrieved from NASA's ASRS site as of July 2013 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.