A TACCO is the aircrew member responsible for coordinating the activities of the part of the crew

Crew

A crew is a body or a class of people who work at a common activity, generally in a structured or hierarchical organization. A location in which a crew works is called a crewyard or a workyard...

 responsible for the tactical operation of the aircraft and its systems. The TACCO may, depending on the country, be the Mission Commander of the crew.

Typically, TACCOs run the missions in P-3 Orion

P-3 Orion

The Lockheed P-3 Orion is a four-engine turboprop anti-submarine and maritime surveillance aircraft developed for the United States Navy and introduced in the 1960s. Lockheed based it on the L-188 Electra commercial airliner. The aircraft is easily recognizable by its distinctive tail stinger or...

 patrol aircraft and S-3 Viking

S-3 Viking

The Lockheed S-3 Viking is a four-seat twin-engine jet aircraft that was used by the U.S. Navy to identify, track, and destroy enemy submarines. In the late 1990s, the S-3B's mission focus shifted to surface warfare and aerial refueling. The Viking also provided electronic warfare and surface...

 aircraft. They are specially trained for antisubmarine warfare tactics, but also participate in other missions in which these aircraft are involved.

Typically, TACCOs run the missions in CH124 Sea King helicopters, P-3 Orion patrol aircraft, and S-3 Viking aircraft.