Narrative:

Enroute from ZZZ1 to ZZZ2; we noted a scent in the cockpit similar to a forest fire smell but no smoke nor fire was visible. 1.5 hr into a 2.5 hr flight; the odor became stronger and I was abeam of ZZZ at 9;000 feet. I notified ATC I was going to divert and upon changing my GPS; noted I was 8 min out. At about 5 min out on normal descent we noted smoke coming into the cockpit area. I could not expedite my descent so I asked ZZZ for runway xx but he was going to take me to runway xy. I [advised ATC] and he gave me runway xx. I executed a normal descent but opened the vent as I decided to avoid compromising my mental ability. It did not increase nor decrease the smoke. I executed a normal landing on runway xx and noted the smoke stopped and communicated this to the tower. We opened the door; side window and vents on the ground and the smoke resumed.I immediately stopped the aircraft; turned off the engine; electric and fuel and exited the aircraft.it was determined that paper towels in the forward baggage area came to rest against the light bulb in the compartment and were smoldering. I removed them and examined the compartment; removed the cowling and examined the engine and we found absolutely no damage from the incident. We declined EMS (emergency medical services) help but they encouraged a quick check which found we were just fine. I also appreciate their assistance and professionalism.I must add the top to bottom; ATC; ZZZ tower; fire and EMS were eminently professional and helpful and I'm deeply appreciative of all their assistance. I then flew the aircraft onto my destination; 1hour away without incident.

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Original NASA ASRS Text

Title: PA-32 pilot reported aircraft encountered smoke in the cockpit inflight and diverted.

Narrative: Enroute from ZZZ1 to ZZZ2; we noted a scent in the cockpit similar to a forest fire smell but no smoke nor fire was visible. 1.5 hr into a 2.5 hr flight; the odor became stronger and I was abeam of ZZZ at 9;000 feet. I notified ATC I was going to divert and upon changing my GPS; noted I was 8 min out. At about 5 min out on normal descent we noted smoke coming into the cockpit area. I could not expedite my descent so I asked ZZZ for RWY XX but he was going to take me to RWY XY. I [advised ATC] and he gave me RWY XX. I executed a normal descent but opened the vent as I decided to avoid compromising my mental ability. It did not increase nor decrease the smoke. I executed a normal landing on RWY XX and noted the smoke stopped and communicated this to the tower. We opened the door; side window and vents on the ground and the smoke resumed.I immediately stopped the aircraft; turned off the engine; electric and fuel and exited the aircraft.It was determined that paper towels in the forward baggage area came to rest against the light bulb in the compartment and were smoldering. I removed them and examined the compartment; removed the cowling and examined the engine and we found absolutely no damage from the incident. We declined EMS (Emergency Medical Services) help but they encouraged a quick check which found we were just fine. I also appreciate their assistance and professionalism.I must add the top to bottom; ATC; ZZZ Tower; Fire and EMS were eminently professional and helpful and I'm deeply appreciative of all their assistance. I then flew the aircraft onto my destination; 1hour away without incident.

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.