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ZLC center controller reported they observed an aircraft descend below the assigned altitude and below the minimum vectoring altitude.
| Attributes | |
| ACN | 1748658 |
| Time | |
| Date | 202007 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZLC.ARTCC |
| State Reference | UT |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Route In Use | Direct |
| Flight Plan | IFR |
| Person 1 | |
| Function | Enroute |
| Qualification | Air Traffic Control Fully Certified |
| Experience | Air Traffic Control Time Certified In Pos 1 (yrs) 8 |
| Events | |
| Anomaly | ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT |
Narrative:
I cleared aircraft X to 11;000 feet which was the lowest I could clear them. I accidentally said 10;000 feet; but corrected myself and listed to be sure the pilot readback 11;000 feet. They reported weather and that she expected a visual approach and asked for a fix on the RNAV approach to set up for it. I didn't know the fix; but since 11;000 feet was the highest terrain in the area; I told them they could start heading toward the fix while I found it. They turned direct and began descending below 11;000 feet. I first noticed it at 10;500 feet. I asked them to say altitude. They reported 10;500 feet descending to I think 7;200 feet. The fix in question has an altitude of 7;200 feet if you are cleared for the RNAV approach. I gave them a low altitude alert; informed them that they were cleared only to 11;000 feet and told them to climb immediately to 11;000 feet. They said they were starting the climb; but had the field in sight and wanted to cancel IFR. I accepted the cancellation.this was pilot error. Perhaps I should have pursued a pilot deviation.
Original NASA ASRS Text
Title: ZLC Center Controller reported they observed an aircraft descend below the assigned altitude and below the Minimum Vectoring Altitude.
Narrative: I cleared Aircraft X to 11;000 feet which was the lowest I could clear them. I accidentally said 10;000 feet; but corrected myself and listed to be sure the pilot readback 11;000 feet. They reported weather and that she expected a visual approach and asked for a fix on the RNAV approach to set up for it. I didn't know the fix; but since 11;000 feet was the highest terrain in the area; I told them they could start heading toward the fix while I found it. They turned direct and began descending below 11;000 feet. I first noticed it at 10;500 feet. I asked them to say altitude. They reported 10;500 feet descending to I think 7;200 feet. The fix in question has an altitude of 7;200 feet if you are cleared for the RNAV approach. I gave them a low altitude alert; informed them that they were cleared only to 11;000 feet and told them to climb immediately to 11;000 feet. They said they were starting the climb; but had the field in sight and wanted to cancel IFR. I accepted the cancellation.This was pilot error. Perhaps I should have pursued a pilot deviation.
Data retrieved from NASA's ASRS site 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.