Sct controller reported a widebody aircraft on departure procedure could not meet climb rate; result...

Narrative:

Aircraft X advised me that they might not make the inland restriction. I made the necessary point out and approval request. I instructed aircraft X to climb and maintain 140. Aircraft X departed ont and climbed 3;000 feet in approximately 5 NM; and with that rate of climb aircraft X would meet all the MVA's (minimum vectoring area) on the route. However; aircraft X then slowed the rate of climb; climbing approximately 1;000 feet over the next 5 NM. When I observed that aircraft X had reduced the rate of climb; I immediately turned the aircraft away from a higher MVA. I issued the turn and the aircraft began the turn before entering approximately 1/8 nm into the higher MVA; so I issued a low altitude alert as aircraft X entered a 060 feet MVA at 055 feet MSL. After aircraft X was above the MVA I cleared the aircraft to inland and aircraft X flew the SID without further incident. I will issue a dva (diverse vector area) until the aircraft is above the MVA.

Original NASA ASRS Text

Title: SCT Controller reported a widebody aircraft on departure procedure could not meet climb rate; resulting in entering a higher Minimum Vectoring Altitude.

Narrative: Aircraft X advised me that they might not make the inland restriction. I made the necessary point out and approval request. I instructed Aircraft X to climb and maintain 140. Aircraft X departed ONT and climbed 3;000 feet in approximately 5 NM; and with that rate of climb Aircraft X would meet all the MVA's (Minimum Vectoring Area) on the route. However; Aircraft X then slowed the rate of climb; climbing approximately 1;000 feet over the next 5 NM. When I observed that Aircraft X had reduced the rate of climb; I immediately turned the aircraft away from a higher MVA. I issued the turn and the aircraft began the turn before entering approximately 1/8 nm into the higher MVA; so I issued a low altitude alert as Aircraft X entered a 060 feet MVA at 055 feet MSL. After Aircraft X was above the MVA I cleared the aircraft to inland and Aircraft X flew the SID without further incident. I will issue a DVA (Diverse Vector Area) until the aircraft is above the MVA.

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	1556640
Time
Date	201807
Local Time Of Day	1801-2400
Place
Locale Reference	SCT.TRACON
State Reference	CA
Aircraft 1
Make Model Name	Widebody Transport
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Person 1
Function	Departure
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT

Sct controller reported a widebody aircraft on departure procedure could not meet climb rate; resulting in entering a higher minimum vectoring altitude.