TRACON controller described a low altitude alert when clearing an aircraft for an approach outside h...

Narrative:

Center called me and apreqed a C172 at 030 for a GPS approach into ZZZ and I approved it. When the C172 checked in at 030 I cleared them to maintain 030 until established on a segment of the approach and cleared GPS approach. The C172 was still 15 miles outside my boundary. A little later I noticed a low altitude warning on the C172 and did not know why. He was still about 10 miles outside my boundary. I am unfamiliar with the MVA in that area and I then pulled up the MVA map. It showed the MVA at 037. Since the C172 was well past the antennae; I took no action.

Original NASA ASRS Text

Title: TRACON Controller described a Low Altitude Alert when clearing an aircraft for an approach outside his airspace; the reporter not issuing a climb because the aircraft in question had already pasted to obstructing antenna.

Narrative: Center called me and APREQed a C172 at 030 for a GPS approach into ZZZ and I approved it. When the C172 checked in at 030 I cleared them to maintain 030 until established on a segment of the approach and cleared GPS approach. The C172 was still 15 miles outside my boundary. A little later I noticed a Low Altitude warning on the C172 and did not know why. He was still about 10 miles outside my boundary. I am unfamiliar with the MVA in that area and I then pulled up the MVA map. It showed the MVA at 037. Since the C172 was well past the antennae; I took no action.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1002994
Time
Date	201204
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	Approach Departure
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT

TRACON controller described a low altitude alert when clearing an aircraft for an approach outside his airspace; the reporter not issuing a climb because the aircraft in question had already pasted to obstructing antenna.