Date: 202102
Local time of day: 1201-1800
Location: HIO.Tower, OR
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Operator: Personal
Operating under: Part 91
Mission: Personal
Flight phase: Initial Approach
Airspace: Class D HIO
Second aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Aircraft component: GPS & Other Satellite Navigation
Component problem: Malfunctioning
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Confusion; Communication Breakdown; Situational Awareness
Second reporter function: Single Pilot
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Airspace Violation All Types; Conflict NMAC
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action; Flight Crew Executed Go Around / Missed Approach
Contributing factors: Aircraft; ATC Equipment / Nav Facility / Buildings; Human Factors; Software and Automation
Primary problem: Aircraft

Narrative: Aircraft X entered the airspace for 4 miles south of HIO at 020 heading eastbound. I used the ADS-B function on the radar display to determine the call sign. It appeared as if Aircraft X was going to join the pattern at ZZZ; a nearby airport. Aircraft X exited the airspace and was not in conflict with any aircraft. No attempt at communication was made. Aircraft X turned north and re-entered the airspace at 2100 ft.; 4 miles southeast of HIO. Aircraft X then made a right turn and joined a 5 mile final at 1800 ft. Aircraft X broke off of final and flew north; then suddenly rejoined a 3 mile final. This was the first attempt at communication with Aircraft X. I attempted communications and Ground Control attempted communications on their frequency; 121.5; and the practice area frequency.  Aircraft Y was in right traffic for the right side runway and Aircraft X looked like he was joining final for the same runway I changed Aircraft Y to the left runway and issued a full stop landing clearance until Aircraft X was safely on the ground. Aircraft X overflew the right runway and began circling in the north portion of the airspace. Aircraft X was given the green light gun signal multiple times but never landed. In total; 6 different aircraft had their flight paths adjusted to avoid Aircraft X. Aircraft Y called ready for departure; IFR on a SID. I called Approach and requested a 5 minute release to attempt to avoid Aircraft X's erratic flight paths. Aircraft X was on a left downwind heading for the opposite direction runway and had been circling for approximately 15 minutes. I cleared Aircraft Y for takeoff assuming that Aircraft X would continue their right turns and not be a factor for Aircraft Y. Aircraft X suddenly turned a left base and descended just at Aircraft Y was lifting off. I issued a traffic alert for Aircraft Y; who reported the traffic in sight and maneuvered to avoid Aircraft X. It appeared that the closest proximity was 200 ft. lateral and 0 ft. vertical. Aircraft X overflew the runway at 500 ft. and made a left turn northbound. Aircraft Y rejoined the SID and was shipped to Departure Control. Ground Control received a phone call from ZZZ1 Tower; who has been in contact with Aircraft X since he entered HIO airspace. Ground Control advised that Aircraft X is cleared to land on any runway. Aircraft X intercepted a left base for an intersecting runway but flew through final. Aircraft X transitioned outside of the airspace at 1000 ft. Aircraft X was tagged up as 'VIOLTR' and Approach advised that Aircraft X landed at ZZZ1.The backup radios in the Tower are difficult to use. Having a newer; digital; handheld version similar to the ones that pilots use might make it easier to establish communications with a lost pilot. A shout line connected to the other nearby towers might also help.


Second narrative: As the pilot in command; I departed in my airplane on a VFR cross country flight to ZZZ1. The aircraft has an installed GNS 430W GPS and GTX-330ES transponder providing ADSB capability. The route of flight followed a basically southerly course direction; with route guidance provided by the G430W direct to my destination. Approximately 15 to 20 miles from my destination; I announced my intention to land. The GPS map course indicated that I was closing in on what was indicated to be my destination; and I made preparations to land; with a call to Tower; indicating my intentions. Having received no response; I maneuvered the aircraft west of the airport in an attempt to gain some time for working out the communication problem. Eventually; I received a broken communication that provided clearance to land. I set up my approach and noticed that the runway markings did not match up to what I expected and did not land. I found out later that I was at a nearby airport however; and this did not correspond to my Garmin 430W readout. Given the communications issues I was having; I contacted my son with my cell phone; who was on the ground having traveled there independently. He contacted the Tower; indicating there was a problem with my flight. The Air Traffic Controller on duty; at that time; was able to locate my aircraft almost immediately and provided vectors. Communications between my aircraft [and ATC] improved as I flew closer to the airport. I made a safe; uneventful landing.To summarize; it is apparent that there were significant issues with medium to long range communications and erroneous GPS information that directly caused concerns with this flight. There was nothing obvious indicating that there was equipment failure on board my aircraft; at that time or subsequently. The return trip was perfectly normal; with support from ATC flight following the entire way; later that evening.The real concern comes down to bad GPS tracking data; which placed me in the wrong airport airspace unintentionally; whereas; I had reason to believe; based on erroneous information; that I was receiving correct information pursuant to an airport arrival at my intended destination There have been published reports of military GPS interruptions for testing and training purposes in the area that are known to have impacted civilian aircraft. Perhaps such jamming activities disrupted my GPS on board; thus would have provided inaccurate location guidance to my Garmin 430W.


Synopsis: Pilot and a Tower Controller reported the pilot flew to the wrong airport. The pilot reported the error was likely due to the pilot's GPS giving false indications or being jammed.