On a buoy report, the average wave period (seconds) of all waves during the 20-minute period.

Avalanche Photo Diode: A photodiode designed to take advantage of avalanche multiplication of photocurrent to provide gain. As the reverse-bias voltage approaches the break-down voltage, hole-electron pairs created by absorbed photons acquire sufficient energy to create additional hole-electron pairs when they collide with ions. Thus a multiplicati [..]

Abbreviation for avalanche photodiode. Note: apd and a.p.d. are also used.

High-speed transport. Nicknamed the 'Able-Peter-Dog', these were destroyers modified to carry a company of Marine Raiders

Afferent Pupillary Defect See Afferent Pupillary Defect

Automatic Payroll Deduction. This payment option is available for eligible TAMU employees and automatically deducts the parking permit cost from an employee's paycheck. This option is an alternative to paying the entire cost of a permit at the time of purchase. The amount deducted is dependent upon payroll details including an employee& [..]

Auto Power Down.

Aircrew Program Designee. A pilot working under an airline training program who has been given the FAA’s blessing to conduct type-rating evaluations in the aircraft for which he/she is rated.

On a buoy report, the average wave period (seconds) of all waves during the 20-minute period.

Air Passenger Duty (UK only): An excise duty charged on the carriage of passengers flying on an aircraft with an authorised take off weight of more than ten tonnes or more than twenty seats. Due when the aircraft first takes off on the passenger’s flight and is payable by the aircraft operator

Application for permit to drill

On a buoy report, the average wave period (seconds) of all waves during the 20-minute period.