[rentacow]

I use the following approach to quickly find and destroy a lone submarine:



Step One, MAD sensor deployed and on. Speed to high, altitude to MAD search. I will use the "C" key to quickly set a course on the map* to the point where I want to start looking for the sub. Finally I will configure all of my torpedoes in advance for the following release: CIRCLE SEARCH, set a ceiling to protect surface ships, set a max depth so the torp doesnt run into the bottom, select a search mode and appropriate speed for that mode and current conditions, etc.
* Avoid using waypoints with the helo. Give the pilot a course directly so that when you order stop and hover, the pilot will STAY hovering while you can orient the helo in step 4. Accidentally moving any waypoint will cause the pilot to resume course, potentially while the dipping sonar is deployed.

Step Two, over the initial search area(s), I'll drop a BT bouy and one or two sonobouys as needed, but I don't intend to "find" the sub with sonobouys. The purpose of these bouys is simply to determine if an area (~2 mile radius) of ocean is safe to "Stop-n-Dip" over.

Keep moving while dropping these bouys! Slow down to medium speed or even slow to make sharp turns and clear the general area while the bouys connect. Gain a few hundred feet of altitude now to ensure you stay in range of the bouy data link, and to keep the MAD sensor from catching a wave at the lower speeds. You should at least keep moving until you know there are no threats immediately near the bouys. Those bouys make splashes, and if there's one thing that a sneaky submarine captain hates more than helicopters, it's littering.

Step Three, now I have a nice safe place to go hover over and deploy my dipping sonar. This is how I intend to find the enemy sub. It's a VERY badass sensor. This baby can hear a nuke sub up to something like 20 miles away in optimal conditions. Realistically you can expect 5-8 miles reliably. It has narrowband capability for getting a positive ID.

If I don't hear the target near the initial search area(s), I will go back to step 2 and clear a new search area with bouys as needed.

Step Four, The dipping sensor will give me a passive line of bearing to the ID'd target. I will order the pilot to that course while I reel in the dip and re-establish MAD search altitude. Need to work quickly now before that bearing line gets too cold. Once the dipper is clear of the water, I'm ordering "warp drives engage" top speed.

Step Five, I'm using the camera pod to keep an eye out for surface vessels or anything which could set off the MAD in error, and wait. If there is no joy within 20 miles, go back to step 3. Try "leading the target" a bit more or less on the next pass.

When I hear "MAD! MAD! MAD!" and see nothing on the surface made of metal...
Weapons were setup in step one, so all that's left to do is click the weapon release button while flying clear of the area, maintaining at all times the warp 10 velocity from step 4. The target will be really pissed off when he hears the fish and may blow ballast, so I always want to mind the 3 mile SAM radius.

Bonus Tips:

The 3 Mile SAM radius is exceedingly important anytime you are outside the ASM missile coverage range of your fleet or home ship. During ASW all of your tactics must be mindful of this. Making a splash while hovering, or using your dipping sonar over an unknown or hostile piece of ocean is not safe.

The RA mod allows you to specify LEFT or RIGHT turning CIRCLE SEARCH pattern. You could set up at least 1 torpedo for LEFT search and 1 for RIGHT, then you can conveniently drop the one which is most appropriate for the engagement (enemy evading to the left or right).

The MAD sensor will alert on your dropped torpedo, don't get confused by this. Manually drop this contact to prevent map clutter.

Don't drop the target MAD contact, Do place a marker over it. If you get a second MAD hit on that sub later on, the contact will update automatically on the map. Then you can plot the targets motion between the points.

While hovering, you will still see SOME indicated airspeed depending on your orientation to the wind. Be mindful of this when determining if you are slow enough to deploy the dipping sonar.