Narrative:

I was working tower radar position. Aircraft X; C421; at 180 KTS and VFR; departed ZZZ and was switch to me. I radar identified him and cleared him into the bravo airspace. He was also handed off to the next controller because he wanted an altitude higher than my airspace. I told him to proceed to ZZZ1 and expect to cross runway xx east side of runway and maintain at or below 2;000 ft. He read it back and I was watching him to make sure he followed my instructions. He flew about a 2 miles and appeared to be heading on about a 090 heading; so I issued him 180 heading to get him back towards the airport; which he read back. He still was not turning; so I issue him a 220 heading that was also read back; then traffic 12 o'clock 3 mile a B737 on final for [runway] yyr. He reported the aircraft in sight and I looked out the window and had both of them in sight. The weather was 10+ [SM] and clear. At that time he reported that he must be having problems with his equipment and he is working on it. He appeared to be heading between a 090 and 130 heading. I was giving him some [time] to work things out and see what his next action was going to be so I could respond; since hadn't flown the headings I had issued. He was also no factor to any other aircraft. Then all the sudden; he turned southbound to what looked like a 180 heading; four miles after it was issued the turn. That turn took him right into a 2;400 ft MVA in our airspace that we don't own. At that point I felt it was the safest thing just to let him continue southbound below the MVA and coordinate with next controller that he was having navigational problems. I didn't want to turn him with the navigation problems that he was having or climb him because of arrivals into both ZZZ1 and ZZZ2. This is when I had the error; because on the 180 heading it flew him into the MVA and I did nothing once he was in it; but let him continue safely southbound.I recommend to look at our airspace. We are expected to work aircraft which are one transmission away from having an oe or od. One of the things I could have requested was a climb; but when TRACON is running arrivals into ZZZ2 there's a good chance they weren't going to approve it. I could have climbed him and took an od; but with arrivals into ZZZ2 I felt it wasn't the safest operation. Management's suggestion was let him continue eastbound. That was my plan; but then he just took a heading I am not sure if was the 180 or 220 and I wasn't going to turn him back into final. Yes; I could have given him a 090 heading; but who knows if he would have flown it. To prevent re-occurrence of this event; I am not required to provide overflights; so I have quit doing them. Are we providing a service to the flying community? Our hands are so tied with whole MVA issues that most controllers at ZZZ1 are not taking the risk of having an oe or od. Most of the controllers are just not working overflights anymore.

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Original NASA ASRS Text

Title: Tower Controller described an MVA infraction when a VFR overflight failed to respond to turn instructions; indicating NAV equip problems. The reporter choose the MVA error in lieu of an airspace violation.

Narrative: I was working Tower RADAR position. Aircraft X; C421; at 180 KTS and VFR; departed ZZZ and was switch to me. I RADAR identified him and cleared him into the Bravo airspace. He was also handed off to the next Controller because he wanted an altitude higher than my airspace. I told him to proceed to ZZZ1 and expect to cross Runway XX east side of runway and maintain at or below 2;000 FT. He read it back and I was watching him to make sure he followed my instructions. He flew about a 2 miles and appeared to be heading on about a 090 heading; so I issued him 180 heading to get him back towards the airport; which he read back. He still was not turning; so I issue him a 220 heading that was also read back; then traffic 12 o'clock 3 mile a B737 on final for [Runway] YYR. He reported the aircraft in sight and I looked out the window and had both of them in sight. The weather was 10+ [SM] and clear. At that time he reported that he must be having problems with his equipment and he is working on it. He appeared to be heading between a 090 and 130 heading. I was giving him some [time] to work things out and see what his next action was going to be so I could respond; since hadn't flown the headings I had issued. He was also no factor to any other aircraft. Then all the sudden; he turned southbound to what looked like a 180 heading; four miles after it was issued the turn. That turn took him right into a 2;400 FT MVA in our airspace that we don't own. At that point I felt it was the safest thing just to let him continue southbound below the MVA and coordinate with next Controller that he was having navigational problems. I didn't want to turn him with the NAV problems that he was having or climb him because of arrivals into both ZZZ1 and ZZZ2. This is when I had the error; because on the 180 heading it flew him into the MVA and I did nothing once he was in it; but let him continue safely southbound.I recommend to look at our airspace. We are expected to work aircraft which are one transmission away from having an OE or OD. One of the things I could have requested was a climb; but when TRACON is running arrivals into ZZZ2 there's a good chance they weren't going to approve it. I could have climbed him and took an OD; but with arrivals into ZZZ2 I felt it wasn't the safest operation. Management's suggestion was let him continue eastbound. That was my plan; but then he just took a heading I am not sure if was the 180 or 220 and I wasn't going to turn him back into final. Yes; I could have given him a 090 heading; but who knows if he would have flown it. To prevent re-occurrence of this event; I am not required to provide overflights; so I have quit doing them. Are we providing a service to the flying community? Our hands are so tied with whole MVA issues that most controllers at ZZZ1 are not taking the risk of having an OE or OD. Most of the controllers are just not working overflights anymore.

Data retrieved from NASA's ASRS site as of April 2012 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.