Abaft - Aft of; farther aft than.
Category: - Maritime

Abeam - At right angles to, or beside, the boat
Category: - Maritime

Able Bodied Seamen - A member of the deck crew who is able to perform all the duties of an experienced seamen; certificated by examination; must have three years sea service. Also called Able Seamen and A.B.
Category: - Maritime

Aboard - On or in the boat
Category: - Maritime

Above sea level - Describes an aircraft's height above the sea. It should not be confused with AGL which is the height above ground level.
Category: - Maritime

ABS - American Bureau of Shipping: A U.S.-based private classification, or standards setting society for merchant ships and other marine systems.
Category: - Maritime - Acronym

Absolute Location - A location in geographic space given with respect to a known origin and standard measurement system, such as a coordinate system.
Category: - GIS

AC - The Aircraft Commander is the Pilot in charge of the aircraft and its crew. He/she makes the final decisions (in consultation with the other crew members) on how the rescue will be carried out. The AC is not necessarily the highest ranking member of the crew, but he/she is the most qualified Pilot.
Category: - Acronym - SAR

A/C - Aircraft, both helicopters and airplanes. The term Fixed or Rotary Wing will often be used to describe the different types. (SEE Fixed Wing or Rotary Wing.)
Category: - Acronym - SAR

ACC - Area Control Centre (for airspace)
Category: - Acronym - SAR