PCA (plural PCAs)
- (aviation) Abbreviation of propulsion controlled aircraft (system/unit), an aircraft with a control system with two or more engines arrayed abreast, allowing descent, ascent, turns by adjusting the throttle control to the engines (sometimes used attributively).
- (statistics) Abbreviation of principal components analysis.
- (medicine) Abbreviation of patient-controlled analgesia; palliator.
- (aviation): PIO (pilot-induced oscillation)