Magnetic Anomaly Detector (MAD) Sea Power
See Magnetic Anomaly Detector Naval Warfare PMC Tactical.
In Sea Power your helicopters and aircrafts are equipped with MAD devices, for example US Navy SH-2F Sea Sprite has this device. It works by you ordering the helicopter (helo) to fly at 20ft altitude. MAD will be towed behind the helicopter to avoid the helos electric charge or something like that.
In order to deploy MAD order helicopter to drop down to 20ft altitude (height), you'll find the navigation altitude/height order from bottom left corner of the GUI, as seen in below image.
Once helicopter reaches 20ft it will automatically deploy MAD device.
Then once you get lucky enough and fly directly over a submerged submarine, you will get a new contact report about the sub.
Here is another example image of Sea Sprite helicopter using MAD device.
