A center controller reported they observed an aircraft that descended below the assigned altitude an...

Attributes
ACN	1747607
Time
Date	202006
Local Time Of Day	1801-2400
Place
Locale Reference	ZLC.ARTCC
State Reference	UT
Environment
Light	Daylight
Aircraft 1
Make Model Name	Small Transport
Operating Under FAR Part	Part 91
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) 9.0
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT

Narrative:

Aircraft X was enroute. I thought I issued a descent to 11000 feet. They were passing through a 11000 MVA (minimum vectoring altitude) area. I saw aircraft X descend to 10800 feet; then 10600 feet. I asked if aircraft X was maintaining 11000 feet. Aircraft X answered that they had been cleared to 10000 feet. I issued them 11000 feet and to expect lower in one minute. Aircraft X stopped their descent but did not appear to climb back up. Aircraft X remained at 10600 feet for approximately 5 miles in the 11000 foot MVA area. Listen carefully for readbacks; especially if the aircraft has a scratchy radio.

Original NASA ASRS Text

Title: A Center Controller reported they observed an aircraft that descended below the assigned altitude and below the Minimum Vectoring Altitude did not climb back to the assigned altitude when instructed.

Narrative: Aircraft X was enroute. I thought I issued a descent to 11000 feet. They were passing through a 11000 MVA (Minimum Vectoring Altitude) area. I saw Aircraft X descend to 10800 feet; then 10600 feet. I asked if Aircraft X was maintaining 11000 feet. Aircraft X answered that they had been cleared to 10000 feet. I issued them 11000 feet and to expect lower in one minute. Aircraft X stopped their descent but did not appear to climb back up. Aircraft X remained at 10600 feet for approximately 5 miles in the 11000 foot MVA area. Listen carefully for readbacks; especially if the aircraft has a scratchy radio.

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.

A center controller reported they observed an aircraft that descended below the assigned altitude and below the minimum vectoring altitude did not climb back to the assigned altitude when instructed.