D10 controller reported a twin cessna pilot descended below clearance in low IFR weather.

Narrative:

On the day of the incident it was lifr [low instrument flight rules] conditions. Aircraft X had just departed runway xx from ZZZ; and had called me for his check on at about 023 ft. I told him 'radar contact; climb and maintain 040'. I then went on with my scan of my sector; and when I came back to aircraft X; I noticed his altitude was 015 [feet]; the pilot had descended on his own; I then asked if everything was ok and if he needed any assistance. The pilot informed me that he was having control issues and was having a hard time keeping his plane in level flight. I told him ZZZ was 4 or 5 miles south of him if he wanted to return; I then informed the supervisor of what was going on and coordinated with ZZZ about the situation. The pilot asked me what highway he was flying over; I informed him and ZZZ was 3 miles south/southwest of him. The pilot then informed me he lost all his instruments. I then continued to inform him of his position in relation to ZZZ. I also coordinated with ZZZ to issue the pilot a landing clearance if/when he got ZZZ in sight. Thankfully; the pilot was able to finally see ZZZ about 1.5 miles from the field; I issued a landing clearance and switched the pilot over to ZZZ tower and the pilot did land safely. While I did not issue the 'low altitude alert'; which was the reason this incident was brought up again for [report] purposes; I was so engrossed in trying to get the plane and pilot back to the ground safely I should have issued the 'low altitude alert'.

Original NASA ASRS Text

Title: D10 Controller reported a twin Cessna pilot descended below clearance in low IFR weather.

Narrative: On the day of the incident it was LIFR [Low Instrument Flight Rules] conditions. Aircraft X had just departed RWY XX from ZZZ; and had called me for his check on at about 023 ft. I told him 'Radar contact; climb and maintain 040'. I then went on with my scan of my sector; and when I came back to Aircraft X; I noticed his altitude was 015 [feet]; the pilot had descended on his own; I then asked if everything was ok and if he needed any assistance. The pilot informed me that he was having control issues and was having a hard time keeping his plane in level flight. I told him ZZZ was 4 or 5 miles south of him if he wanted to return; I then informed the Supervisor of what was going on and coordinated with ZZZ about the situation. The pilot asked me what highway he was flying over; I informed him and ZZZ was 3 miles S/SW of him. The pilot then informed me he lost all his instruments. I then continued to inform him of his position in relation to ZZZ. I also coordinated with ZZZ to issue the pilot a landing clearance if/when he got ZZZ in sight. Thankfully; the pilot was able to finally see ZZZ about 1.5 miles from the field; I issued a landing clearance and switched the pilot over to ZZZ Tower and the pilot did land safely. While I did not issue the 'low altitude alert'; which was the reason this incident was brought up again for [report] purposes; I was so engrossed in trying to get the plane and pilot back to the ground safely I should have issued the 'low altitude alert'.

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	1581106
Time
Date	201809
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	Golden Eagle 421
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
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) 3.5
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT