A Navy dipping sonar “departed” from a helicopter last week during training off the California coast, but officials on Thursday wouldn’t say if they’d found it.

The Airborne Low Frequency Sonar, or ALFS, device fell off an MH-60R Sea Hawk helicopter while Helicopter Maritime Strike Squadron 71 conducted night training on Aug. 6 near San Diego, according to Naval Air Forces spokesman Lt. Travis Callaghan.

“Until the investigation is complete, I can’t confirm if it’s been recovered or not,” Callaghan said in an email to Navy Times.

The Navy has categorized the ALFS loss as a “Class A” mishap, which is reserved for accidents involving more than $2 million in property damage.

ALFS is a vital tool in the Navy’s anti-submarine warfare kit. It’s carried by helicopters and can be lowered hundreds of feet into the ocean.

“The ALFS sonar, known as a transducer, is capable of identifying a submarine down to its name by reading its vibration signature as it moves through the water,” according to the Navy.

The ALFS accident is the seventh Class A mishap at sea since the federal fiscal year began on Oct. 1, according to Navy records.

The Navy recorded 14 similar mishaps in FY 2018.