The French Navy has revealed the loss of the variable-depth active sonar body from the Type F 67 anti-submarine frigate De Grasse. Part of the DSBX-1 SLASM anti-submarine sonar suite, the towed body was lost after being deployed in heavy seas during exercises in the Bay of Biscay on 24th March. SLASM was the first active very low-frequency sonar to enter service anywhere in the world. The system is primarily deployed in support of the Force Océanique Startégique, France's submarine deterrent force. An inquiry was under way into whether the De Grasse's commanding officer should have deployed the variable-depth sonar in heavy seas. The sonar body was worth EUR3 million and it was merely a component of the system fitted to the frigates ar a total cost of EUR150 million.