Sct TRACON controller reported a helicopter descended below the MVA while issuing a wildfire report.

Narrative:

Aircraft X came from joshua approach IFR south; level 8;000 ft; landing sbd. Behind it was aircraft Y at 10;000 ft for sna (approximately 5 miles). I wanted to get the aircraft Y down to 8;000 ft and on a heading to hand off to hemet sector; for the kayoh arrival. Aircraft X was landing sbd anyhow; so I stepped him down to 7;400 ft (the MVA in that area) to get him as low as possible for the approach and so I could keep aircraft Y going down above him until he flew past. I then noticed the helicopter dipped below 7;400 ft to 7;200 ft so I started watching; and as it continued down to 7;000 ft; he keyed up and started telling me the location of a fire he saw. He was giving me a lot of detail about the fire; and meanwhile his altitude kept on going down; until he finally unkeyed as he was descending thru 6;700 ft. I told him to climb back up to 7;400 ft; and then gave him the low altitude alert phraseology.2 things I have thought about: maybe an odd altitude like 7;400 ft is a confusing altitude for pilots; since normally we assign altitudes in increments of 1;000 ft.the other is I should have jumped on the altitude discrepancy as soon as I saw the aircraft dip below 7;400 ft; versus waiting and watching; and then being unable to do anything because of frequency usage.

Original NASA ASRS Text

Title: SCT TRACON Controller reported a Helicopter descended below the MVA while issuing a wildfire report.

Narrative: Aircraft X came from Joshua approach IFR south; level 8;000 ft; landing SBD. Behind it was Aircraft Y at 10;000 ft for SNA (approximately 5 miles). I wanted to get the Aircraft Y down to 8;000 ft and on a heading to hand off to Hemet sector; for the KAYOH arrival. Aircraft X was landing SBD anyhow; so I stepped him down to 7;400 ft (the MVA in that area) to get him as low as possible for the approach and so I could keep Aircraft Y going down above him until he flew past. I then noticed the helicopter dipped below 7;400 ft to 7;200 ft so I started watching; and as it continued down to 7;000 ft; he keyed up and started telling me the location of a fire he saw. He was giving me a lot of detail about the fire; and meanwhile his altitude kept on going down; until he finally unkeyed as he was descending thru 6;700 ft. I told him to climb back up to 7;400 ft; and then gave him the low altitude alert phraseology.2 things I have thought about: Maybe an odd altitude like 7;400 ft is a confusing altitude for pilots; since normally we assign altitudes in increments of 1;000 ft.The other is I should have jumped on the altitude discrepancy as soon as I saw the aircraft dip below 7;400 ft; versus waiting and watching; and then being unable to do anything because of frequency usage.

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	1525744
Time
Date	201803
Local Time Of Day	0601-1200
Place
Locale Reference	SCT.TRACON
State Reference	CA
Environment
Light	Daylight
Aircraft 1
Make Model Name	Helicopter
Flight Phase	Descent
Flight Plan	IFR
Aircraft 2
Make Model Name	TBM 700/TBM 850
Flight Phase	Descent
Route In Use	STAR KAYOH
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 15
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT