A11 controller described a descent below MVA; apparently a pilot error; the reporter noting the simi...

Narrative:

A BE20 was inbound to anc via yeska. He was told to expect runway 7R and to descend and maintain 080. He read it back. I issued traffic on a primary northbound target when I noticed that he was at 075 in a 080 MVA. I asked him to verify maintaining 080. He said correcting. I asked if he could maintain his own terrain and obstruction clearance. He said yes. I instructed him to maintain his own terrain and obstruction clearance. He asked if I still needed him at 080 and I said yes. He climbed to 080. When I said yes to his question of still needing him at 080 I didn't use his call sign. I just said yes. We have had instances where aircraft do descend below the 080 MVA. The general thought is that because we are telling to expect a runway (usually 7R or 7L) whose number is so close to the MVA number (080) that it sometimes leads to confusion for the pilots and they input 070. Some controllers won't issue both the runway assignment and the altitude in the same transmission. Others will issue 090 since it sounds more distinct and allow for a 1;000 ft buffer from MVA.

Original NASA ASRS Text

Title: A11 Controller described a descent below MVA; apparently a pilot error; the reporter noting the similarity between runway and altitude assignments may have contributed to the error.

Narrative: A BE20 was inbound to ANC via YESKA. He was told to expect Runway 7R and to descend and maintain 080. He read it back. I issued traffic on a primary northbound target when I noticed that he was at 075 in a 080 MVA. I asked him to verify maintaining 080. He said correcting. I asked if he could maintain his own terrain and obstruction clearance. He said yes. I instructed him to maintain his own terrain and obstruction clearance. He asked if I still needed him at 080 and I said yes. He climbed to 080. When I said yes to his question of still needing him at 080 I didn't use his call sign. I just said yes. We have had instances where aircraft do descend below the 080 MVA. The general thought is that because we are telling to expect a runway (usually 7R or 7L) whose number is so close to the MVA number (080) that it sometimes leads to confusion for the pilots and they input 070. Some controllers won't issue both the runway assignment and the altitude in the same transmission. Others will issue 090 since it sounds more distinct and allow for a 1;000 FT buffer from MVA.

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	986560
Time
Date	201201
Local Time Of Day	1801-2400
Place
Locale Reference	A11.TRACON
State Reference	AK
Aircraft 1
Make Model Name	Super King Air 200
Operating Under FAR Part	Part 135
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach Departure
Qualification	Air Traffic Control Developmental
Person 2
Function	Pilot Flying Captain
Experience	Flight Crew Last 90 Days 46 Flight Crew Total 4024 Flight Crew Type 822
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance

A11 controller described a descent below MVA; apparently a pilot error; the reporter noting the similarity between runway and altitude assignments may have contributed to the error.