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.
Synopsis
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.
Second reporter narrative
I was descending to 8;000 FT proceeding direct to ANC VOR. It was a clear day; and seemed to be low traffic for ANC. I was hand flying the approach; and had called the airport in sight around 9;000 FT. The airplane had an altitude alerted; and it illuminated at 9;000 above my preset altitude of 8;000 FT. I was told of traffic ahead on final and that I would be number two for the airport. Due to the mountains east of Anchorage; Approach keeps you high until clear of terrain. Therefore; I was using a high rate of descent; due to the close proximity of the field (approximately 16 NM). Being a single pilot operator; I had a high workload; and was anticipating a Visual Approach before reaching 8;000 FT. In the mean time; I was dialing in the ILS 7R; which I was told to expect. While doing so; I neglected to level at 8;000; and heard the altitude alerted chime at 7;700 FT. I immediately began a level off; but didn't get stopped until 7;600 MSL. Approach called to verify an altitude of 8;000 FT; to which I responded that I was correcting to. I was given a number to call Approach after landing. The rest of the flight was without incident. Retrospect; and for future flights; I will stop trying to do multiple things within one thousand feet of an assigned altitude. A mental or verbal call out within 1;000 and again at 300 FT of the altitude would have helped to prevent this deviation. It was completely unintentional; and I was correcting before Approach called me on the radio. Perhaps the anticipation of a Visual Approach also contributed to the incident. These things will be taken into consideration by me in the future; in hopes of preventing another similar occurrence.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.