I took my IFR checkride a couple weeks ago and unfortunately ran into issues with the GPS approach. The approach was the last one of the flight. For the previous two approaches (an ILS and a Localizer partial panel) I had the approach loaded into my airplane's KLN 94 and had the moving map up for situational awareness. When I flew the hold, I put the GPS into OBS mode as I approached the holding fix, set Nav 1 to the inbound course of the hold, and flew the hold by tracking the CDI for the inbound course. Simple enough.
The problem was when I asked for the GPS and approach vectored me out of the hold. I set up the approach in the GPS but forgot to switch back from OBS to LEG mode. I got to the IAF but of course, the GPS didn't sequence onward to the IF. At the time I had no idea why this was happening, and I asked approach if I could get vectors to try the approach again. The examiner was ok with this, but since I was still in OBS, the GPS again wouldn't sequence from the IAF to the IF. At this point I simply told the examiner I had no idea what was happending-he had my take the hood off and fly back VFR, I knew that was it.
When we got back to his office he explained that we had been in OBS, and I couldn't believe I hadn't caught it. He also wanted to do the partial panel approach again, and so I met with my instructor a few days later to fly the same localizer partial panel, followed by the hold, then the GPS for a circle to land. I was fairly confident after the checkride I wouldn't make the same mistake with OBS again.
The trouble is I did. In fact I've flown three flights with my CFI since the checkride and I've failed to take the GPS out of OBS in the hold two out of those three times. I honestly can't explain it. My instructor has told me that my flying otherwise is fine-I'm good with staying ahead of the airplane, running through checklists, briefing approaches, as well as my useage of the KLN 94. For some reason my brain has failed 3 of the 4 previous times to process the fact that I shouldn't be in OBS. On my most recent flight, tonight, we asked for the GPS while in the hold and approach asked us to proceed directly to the IAF. I felt very rushed-I set up the approach quickly in the GPS, scrolled to the IAF, Direct->Enter etc, and at that point felt pleased that I had gotten everything set up in a timely manner and was on my way to the IAF. After about 20 seconds I noticed I was still in OBS! I was pissed beyond belief (I was able to calm down quickly and keep flying the airplane) but I just don't know what I can do differently. After my checkride I add a note about OBS/LEG to my personal checklist for approach briefing. I'm finding that I can't look over every checklist item during flight, just cause of how fast everything moves, and so the last couple times I've just flat out missed that item on my checklist.
Have you (or a student of yours) ever been in a similar situation, be it in IFR or VFR, where one little thing messes up your routine every time (and it's always the same thing)? How did you cope with such a situation? What are your thoughts for how I might approach this problem?
Any thoughts/suggestions/comments would be very welcome and appreciated.