Narrative:

I was working two satellite positions combined due to low volume caused by adverse weather in the area. Aircraft X was inbound to ZZZ from the east through my sector. I vectored aircraft X for his descent and assigned lower altitudes commensurate with the high terrain MVA's northeast of ZZZ. I also pointed the aircraft out to the departure sectors so I could work the aircraft into their areas. As I was doing this for aircraft X; I was also releasing and vectoring two IFR departures from ZZZ1; one arriving at ZZZ2; and the other arriving at ZZZ3. All three of these aircraft required extra coordination with other positions; especially the ZZZ4 arrival for which I needed to coordinate with the arrival coordinator position and then vector for in-trail spacing behind an air carrier. The YYY arrival needed precise vectoring through a narrow channel of airspace over ZZZ4 to get to the next sector; this required a lot of focus to not encroach the finals airspace. I was also getting an updated visibility report from the ZZZ controller to ensure that aircraft X would be able to execute a visual approach from the east. It was during this time that I assigned aircraft X 6;300 ft and didn't hear his read back of 6;000 ft. When I noticed his altitude reaching 6;000 ft he was well clear of the terrain and depicted obstruction but inside the 6;300 ft MVA. Based on my knowledge of the area as a pilot; the aircraft was never in danger and was well clear of the obstruction. I simply missed a read back doing something I rarely do which is assigning an unusual altitude based on an MVA. Due to the rain and clouds in the area; I felt the need to get the pilot below the weather to help him find the airport. I would recommend that certified professional controllers (cpcs) use altitude assignments of thousands of feet and refrain from assigning an unusual altitude based on an MVA unless absolutely necessary. This will reduce the chance of a pilot reading back an altitude incorrectly and the cpcs chance of missing it.

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Original NASA ASRS Text

Title: TRACON Controller described a below MVA event when missing an incorrect read back by the pilot; the Controller suggesting his issuance of 6;300 FT was the confusing factor.

Narrative: I was working two satellite positions combined due to low volume caused by adverse weather in the area. Aircraft X was inbound to ZZZ from the east through my sector. I vectored Aircraft X for his descent and assigned lower altitudes commensurate with the high terrain MVA's northeast of ZZZ. I also pointed the aircraft out to the departure sectors so I could work the aircraft into their areas. As I was doing this for Aircraft X; I was also releasing and vectoring two IFR departures from ZZZ1; one arriving at ZZZ2; and the other arriving at ZZZ3. All three of these aircraft required extra coordination with other positions; especially the ZZZ4 arrival for which I needed to coordinate with the Arrival Coordinator Position and then vector for in-trail spacing behind an air carrier. The YYY arrival needed precise vectoring through a narrow channel of airspace over ZZZ4 to get to the next sector; this required a lot of focus to not encroach the finals airspace. I was also getting an updated visibility report from the ZZZ Controller to ensure that Aircraft X would be able to execute a visual approach from the east. It was during this time that I assigned Aircraft X 6;300 FT and didn't hear his read back of 6;000 FT. When I noticed his altitude reaching 6;000 FT he was well clear of the terrain and depicted obstruction but inside the 6;300 FT MVA. Based on my knowledge of the area as a pilot; the aircraft was never in danger and was well clear of the obstruction. I simply missed a read back doing something I rarely do which is assigning an unusual altitude based on an MVA. Due to the rain and clouds in the area; I felt the need to get the pilot below the weather to help him find the airport. I would recommend that Certified Professional Controllers (CPCs) use altitude assignments of thousands of feet and refrain from assigning an unusual altitude based on an MVA unless absolutely necessary. This will reduce the chance of a pilot reading back an altitude incorrectly and the CPCs chance of missing it.

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.