ASW: On Station with the Orion Crew

Alright now… some of this will be a repeat of info passed along in previous articles. Just trying to keep everyone up to date.  Keep in mind that I am speaking about that which I experienced, and in generalities. There are new capabilities out there, but what I am writing is how things worked “back in the day”, as it were.

So, our intrepid P-3 Orion and crew have arrived on station. Prior to this, their briefing would have included specific data about the target they were after, known tactics employed by the adversary, water and other environmental conditions, plus a host of other communication and intelligence data and protocols.

If this was a part of an on going prosecution of a target, then our crew would be in contact with the Orion currently tracking the target. the crew leaving the op area would pass along what they had done, what the target was doing, what the latest sonobuoy pattern was and where it was located and oriented, and what channels those buoys were. Our AW’s would be monitoring the out-chopping crew’s pattern, so as to maintain a continuous data stream. The TACCO would also be anticipating where the next pattern should be put in, what the spacing should be between sonobuoys, and how the pattern should be oriented.

The first pattern is usually (but not always) made up of LOFAR buoys. these receive sound and transmit it to the aircraft for analysis.  Once contact is generated, the signal strength is analyzed and the TACCO will attempt to plot probable location of the target. Once the strongest signal is recorded, a DIFAR buoy will be dropped alongside that LOFAR buoy. DIFAR not only transmits data, but also gives a magnetic point to the sound source or target.

One the DIFAR buoy has a point, then the TACCO will, with the help of the AW’s, define the distance which they feel direct-path contact can transmit. The Orion will mark on top the position of the DIFAR buoy, and then take up a course along the line of bearing that it indicates. At the point where they believe direct-path contact should be falling off, the crew will drop another DIFAR buoy. If that buoy still points ahead, then it is an indicator that the sound transmission is part of a Convergence Zone effect, and the crew will once again move out a set distance along the line of bearing and continue to drop DIFAR buoys until one points back along that line. That, then, will indicate direct path contact.

Now things happen quickly. Two (or more) DIFAR buoys will be dropped at angles off the line of bearing from the last buoy. These will then be able to give over-lapping lines of bearing that will fix the target’s position through triangulation when they cross. All of this data is being kept on a hard-copy chart plotted by the Navigator, who is also keeping tabs on the aircraft location, etc. It is also plotted and displayed (in the P-3c and later variants) on the TACCO’s screen, the Pilot’s display screen. and a display screen set between the Sensor 1 & 2 positions, so everyone can see what’s developing.

Let me add here a couple of other informational points. The Orion has a 28 track tape recorder that used 1″ magnetic tape on 12″ diameter reels. All of the sensor, TACCO and communications data is recorded for later playback, and also ran through an array of processors at the ASW Operations Center (ASWOC) or TSC (Tactical Support Center).  In addition, the crew has multiple ICS circuits to use which can allow the Tactical Crew to converse without interfering with other stations, or to access all or part of the crew as needs be.

Alright. Once a DIFAR fix has been made, it is tracked so as to develop the course and speed of the target.  If this is a peace-time mission, then one priority is to develop acoustic intelligence about the target. Once the course and speed have been determined, our crew will go out ahead of the target and drop another buoy. The idea is for the target to pass “close aboard”  (CPA: Closest Point of Approach) and the crew can acoustically map the target, thus providing more intelligence about what systems the target is using, where in the hull they are located, etc.

If it’s wartime, then once the course and speed is determined, the TACCO will plot out a pattern of active sonobuoys (pingers, usually CASS buoys) and drop them in advance of the target. He will also drop a couple off at angles to the pattern so as to have them available if the target turns away to either side, etc.

Once the target comes into range, the Sensor Operators will activate the CASS buoys and begin to ping, keeping up a constant relay of range and direction data to the TACCO. By this time, the Orion has descended to less than 1000 feet of altitude and will enter an oval “racetrack” pattern with one long leg matching the target’s course. The Sensor 3 operator will activate the MAD system, and call out “MADMAN!” when it senses contact. A flare will be dropped at the same time to mark the position, and this will be repeated to establish the final fix of the target.

Once the Fix is in, as it were, the TACCO will call for the bomb bay doors to be opened, and request weapon release authorization.  If granted, the Orion will turn into the racetrack and, on the next “MADMAN!” call, the torpedo will be dropped, along with another smoke marker.

At this point, the AW’s will continue to monitor the active as well as passive buoys. They will call out “Torpedo Active” as the screws spool up to speed, and continue to pass target data such as maneuvering, depth changes, etc, to the TACCO. They should also be able to tell aurally when the torpedo has acquired the target, and pass that along as well. Lastly, they will declare when the torpedo detonates, and continue to monitor their systems for further data, such as the target surviving and maneuvering, or for sounds of the target breaking up, etc.

Afterward, it’s all a matter of gathering up all the data, getting your noted in order for the post-flight debrief, and preparing to head back home.

That’s how a typical ASW mission would play out. There are other types of missions, and I’ll talk about those in later articles.

P-3 At Sunset


10 Responses to “ASW: On Station with the Orion Crew”

  1. 1 Byron
    April 3, 2010 at 11:46

    Tim, I’m an old Harpoon player from the way back when. I’ve done so many skunk searches it isn’t funny. Believe it or not, I got pretty good using aviation ASW assets to find that damn sub. Harpoon allows you to do exactly what you talked about. A sensor report will tell me the direction and possible range to the contact. Once I get that, I box him, localize, MAD him, and drop. My only complaint ever was the dinky little MK 46 torps. If you ever found an Oscar, you better have a buddy with more weapons because that damn Oscar was a tough SOB to kill.

    • April 3, 2010 at 14:12


      It’s a great game, but we never had many players up here in our gaming club. Most wanted to play Ironclads (Civil war Naval rules by Yaquinto) or “Wooden Ships & Iron Men”. There’s still some guys who play Fletcher Pratt’s rules for WWI & WWII.

  2. 3 SCOTT the BADGER
    April 3, 2010 at 12:49

    The directional resolution is good enough on the buoys that you can even get a good idea what part of the sub the noises are coming from? WOW! That IS impressive! Do you have to be dropping the bouys quite close to achieve those kind of results, or will a couple of miles still give good results?

    Could your PATRON feed information to COMSUBLANT, in a timely enough fashion, that a LOS ANGELES, or a STURGEON could be vectored in to tail the BEARBOAT, and gather even more info on the sub, and the way it’s skipper handled him? ( I have always thought it interesting that to English speakers, all ships are female, to French and Russian speakers, all ships are male, and I have read that to German speakers, merchies are famale, and warships are male. )

    Please keep the interesting stories coming.

    • 4 Byron
      April 3, 2010 at 13:44

      Be better to whistle up a helo or another P-3 to box the skunk in…

    • April 3, 2010 at 14:10


      The P-3c and later variants all have Data Link Communications Systems that allow for encrypted data transfer between a number of players. It was developed as part of the Aegis system, and allows real-time display of any assets’ data on the screens of any other unit. Thus, the P-3 can transmit it’s data to an Aegis destroyer or cruiser, or an SSN (provided he sticks a mast up to get the data), etc.
      Normally, basic contact data is sent encrypted to a number of players up the chain so that they have an idea of what’s going on. Additionally, there is an encrypted secure voice line that the Pilot or Mission Commander can use to call another player and discuss any issues, etc. It literally is a red phone, the old style handset with a coiled red cable.

    • April 3, 2010 at 14:18

      Regarding acoustic mapping… It’s fairly easy to tell where certain noises are located in the hull. You need to get a buoy fairly close (within 100 yards or so) closer is better. As the contact passes the buoy, the various noise-producing systems will display themselves as various frequencies and harmonics of those frequencies. You will know the contact’s hull length, as well as it’s course and speed, so you mathematically figure out it’s distance from the buoy, and then, by seeing how long and at what intensity a sound manifests itself, you can locate it to a certain area of the hull.
      You’d be amazed at the amount of data you can generate from sounds.

      • 7 Byron
        April 3, 2010 at 22:52

        And the one you really wanted to hear is the thousand trash cans rolling down the hill that meant a sub was no longer a threat. Thank God we never got to that point, and thank the Navy that the Sov’s knew what they were facing.

  3. 8 xbradtc
    April 3, 2010 at 23:27

    Excellent post. In the future, could you give a little more description of the TACCO and his role/station/etc?

    Byron, what iteration of Harp do you play?

    • April 4, 2010 at 01:02

      My pleasure. Thanks for the kind words. I’ll have a post up on the TACCO, and other officer positions, and how the crew has changed over the years.

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