Narrative:

There were two instances of concern on this flight:1. Vectors were provided from hhood to the RNAV-a approach into kttd. This plane's GPS was a recently upgraded to a garmin 650; with which I have very little practice beyond one approach in VFR conditions; and some time on a simulator. The tops were at about 3;000 feet.after being cleared for the approach and stated to maintain at or above 2;500 MSL over woodd; I continued on. The GPS was set to vectors. The GPS did not increment to the next fix; and I did not know how to increment it to the next leg. The controller stated I was on course; so I just turned to follow the course; rather than asking for missed vectors while I get the GPS sorted out. Fortunately; the ceiling was plenty high; so when I broke out about 1/4 mile off course; I was able to cancel IFR and land VFR.-the biggest learning item was that I need to become more familiar with this GPS prior to flying an approach in IFR conditions. This could have been dangerous; had the clouds been lower.2. Also; on this same flight; the haze northeast of the airport was quite severe; although it was VFR. As I was eating lunch; the haze suddenly became much darker and it went to solid IFR conditions. I called and received an IFR clearance from seattle center. Fortunately I was on flight following; so the clearance came quickly. Lessons learned: if it is at all marginal; just get an IFR clearance. Don't try to push on into questionable VFR conditions. It was amazing how fast the haze from the forest fires just slowly became more and more dense until it was too dense to see.

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Original NASA ASRS Text

Title: General aviation pilot reported difficulty with new navigation equipment while on a RNAV approach and experiencing rapidly deteriorating visibility while on a VFR flight.

Narrative: There were two instances of concern on this flight:1. Vectors were provided from HHOOD to the RNAV-A approach into KTTD. This plane's GPS was a recently upgraded to a Garmin 650; with which I have very little practice beyond one approach in VFR conditions; and some time on a simulator. The tops were at about 3;000 feet.After being cleared for the approach and stated to maintain at or above 2;500 MSL over WOODD; I continued on. The GPS was set to vectors. The GPS did not increment to the next fix; and I did not know how to increment it to the next leg. The controller stated I was on course; so I just turned to follow the course; rather than asking for missed vectors while I get the GPS sorted out. Fortunately; the ceiling was plenty high; so when I broke out about 1/4 mile off course; I was able to cancel IFR and land VFR.-The biggest learning item was that I need to become more familiar with this GPS prior to flying an approach in IFR conditions. This could have been dangerous; had the clouds been lower.2. Also; on this same flight; the haze northeast of the airport was quite severe; although it was VFR. As I was eating lunch; the haze suddenly became much darker and it went to solid IFR conditions. I called and received an IFR clearance from Seattle Center. Fortunately I was on flight following; so the clearance came quickly. Lessons learned: If it is at all marginal; just get an IFR clearance. Don't try to push on into questionable VFR conditions. It was amazing how fast the haze from the forest fires just slowly became more and more dense until it was too dense to see.

Data retrieved from NASA's ASRS site 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.