P50 controller vectoring an aircraft in a holding pattern reported an aircraft assigned 10;000 feet ...

Narrative:

Phx was on west flow with a high arrival rate. A large storm from the southeast was rolling in with a dust storm north of it heading towards iwa. I had two IFR inbounds that iwa tower approved to land opposite direction because the dust storm was now on a 7 mile final. My next two IFR inbounds did not want to attempt the active runway so iwa changed runways. I was making point outs to the finals sectors to go further north than usual because of the dust storm.at the time I got a handoff aircraft X was issued a 170 heading and 10000 feet. Aircraft X was on vectors in a box holding pattern waiting for pilot to say intentions. Iwa now had 1/2 mile visibility. Aircraft X didn't respond to the initial heading and altitude I issued as I moved on to another clearance for a different airplane. Aircraft X came back and asked for a southbound heading for weather. I reissued 170 heading and 10000 feet. I heard the read back and moved on. A few minutes later I realized he was at 8200 feet in the 9800 foot minimum vectoring altitude. I asked aircraft X for their current altitude and to say assigned altitude and to stop his descent. He responded with 7000 feet as his assigned altitude. After listening to the replay; the pilot was issued 10000 feet and read back 7000 feet. I then climbed him back to 10000 feet and continued holding for a few more minutes until he diverted. The low altitude alert never went off.

Original NASA ASRS Text

Title: P50 Controller vectoring an aircraft in a holding pattern reported an aircraft assigned 10;000 feet read back 7;000 feet and descended to 8;200 feet which was below the Minimum Vectoring Altitude.

Narrative: PHX was on west flow with a high arrival rate. A large storm from the southeast was rolling in with a dust storm north of it heading towards IWA. I had two IFR inbounds that IWA Tower approved to land opposite direction because the dust storm was now on a 7 mile final. My next two IFR inbounds did not want to attempt the active runway so IWA changed runways. I was making point outs to the finals sectors to go further north than usual because of the dust storm.At the time I got a handoff Aircraft X was issued a 170 heading and 10000 feet. Aircraft X was on vectors in a box holding pattern waiting for pilot to say intentions. IWA now had 1/2 mile visibility. Aircraft X didn't respond to the initial heading and altitude I issued as I moved on to another clearance for a different airplane. Aircraft X came back and asked for a southbound heading for weather. I reissued 170 heading and 10000 feet. I heard the read back and moved on. A few minutes later I realized he was at 8200 feet in the 9800 foot Minimum Vectoring Altitude. I asked Aircraft X for their current altitude and to say assigned altitude and to stop his descent. He responded with 7000 feet as his assigned altitude. After listening to the replay; the pilot was issued 10000 feet and read back 7000 feet. I then climbed him back to 10000 feet and continued holding for a few more minutes until he diverted. The Low Altitude Alert never went off.

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.

Attributes
ACN	1479610
Time
Date	201709
Local Time Of Day	1801-2400
Place
Locale Reference	IWA.Airport
State Reference	AZ
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 1
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT

P50 controller vectoring an aircraft in a holding pattern reported an aircraft assigned 10;000 feet read back 7;000 feet and descended to 8;200 feet which was below the minimum vectoring altitude.