General aviation pilot reported navigational confusion resulting in being off course and below charted altitudes under IFR in an area of rising terrain. The pilot climbed aggressively into rising terrain; then continued to join the approach and land.
Synopsis
General aviation pilot reported navigational confusion resulting in being off course and below charted altitudes under IFR in an area of rising terrain. The pilot climbed aggressively into rising terrain; then continued to join the approach and land.
Narrative
I requested the ILS 27 into RKS with entry at DIGNY. I was asked if I could be vectored; I agreed and entered the ILS 27 approach via vectors into my GTN 750. I was given a downwind vector and cleared direct DIGNY at or above 10;000 to joint the final approach course. I was told I could switch frequencies and I was cleared for the approach.I pulled up my flight plan to go direct. I had already entered the approach with 'vectors to final.' I was surprised that DINGY was NOT an option on my GTN 750. I remembered the fix was off my left shoulder so I dialed the heading bug to cross the final approach fix to where I thought DIGNY was located. I joined the final approach fix and reloaded the approach hoping that DIGNY would be viewable on the approach. It did not appear when I reloaded it. I noticed that my GTN had already sequenced me to EPULE or HEBUM ( I think it was HEBUM but I am not sure). Since they are fixes past DIGNY; I incorrectly assumed I had passed DIGNY (because the GTN 750 had sequenced to the next fix) so I started my decent.At this point; I was very confused because I thought I was passed DIGNY and late descending but I could tell the GS (glide slope indicator) was not available and I could not figure out why the Glide slope indicator was not available. I re-entered the approach for a second time hoping to resolve the problem.I realized I was off course and considered calling ATC but at that time; I got an altitude alert and I realized I was low. Fortunately; I could see the ground and had recently exited the clouds and knew I was not at risk for running into the ground. I started to climb but the terrain also started to rise so I had to climb aggressively to get out of trouble. Once I climbed to safety; I realized what happened and my glide slope was visible and I was able to join the approach and continue uneventfully.This occurred in a desolate area of Wyoming. Weather was complicated by intermittent layers of IMC and concern for icing although I did not encounter any icing.I am current and fly about 200 hrs annually (regularly do approaches but rarely to minimums).Until this event; I would have considered myself a good IMC pilot.In retrospect the problem was the fact that I thought I was past DIGNY and I could not figure out why everything was not making sense. I obviously was not to DIGNY and my decent was early and could have scary if I did not have my terrain alerts. I considered changing frequencies and requesting vectors but I did not understand I was off course. Rather; I thought I was having a GTN problem caused by my recent database update. At the same time I was considering switching back to Center frequency; I had to urgently climb to avoid terrain. Once I climbed to safety; I had everything figured out and decided to contact Center on the ground.I was taught to never use 'vectors to final' on an approach because of this situation. However; I firmly believed that new updates to the GTN did in fact show the fixes along the approach to avoid this situation. Clearly that is not the case. Only some of the fixes are visible.
Second reporter narrative
[Report contained no additional information.]
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.