Definition
A category of aircraft instruments that measure air pressure -- either from the surrounding atmosphere, from inside the engine, or from various aircraft systems -- and display that information to the pilot. This group includes pitot-static instruments (altimeter, airspeed indicator, vertical speed indicator), engine pressure gauges (manifold pressure, oil pressure, fuel pressure), and other pressure-driven indicators used to monitor aircraft performance and system health.
Plain English
Instruments in the cockpit that work by measuring pressure. Some measure outside air pressure to tell the pilot things like altitude and speed. Others measure pressure inside the engine or systems to show whether everything is running correctly.
Context Anchor
Seen in instrument flying when studying the altimeter, airspeed indicator, vertical speed indicator, and the pitot-static system that feeds them.
Derivation
From the Latin pressura, meaning 'a pressing.' The term simply names the common method these instruments share -- they all 'read' something by sensing how hard a fluid (air, oil, fuel) is pressing on a sensor.
Why Pilots Care
Accurate pressure indications are required for determining airspeed, altitude, vertical speed, and engine health, directly affecting flight safety and performance decisions.
Grounding Statement
As the airplane climbs, descends, or speeds up, the air pressures reaching the instruments change, and the instruments turn those pressure changes into readings the pilot can use.
Intuition Check
Do not read “pressure indicating systems” as any system that shows pressure, such as oil pressure or fuel pressure. In this instrument-flying context, it means the air-pressure systems used for flight instruments like altitude, airspeed, and vertical speed.
Example Sentence 1
During the preflight briefing, the instructor explained that the altimeter, airspeed indicator, and manifold pressure gauge are all part of the aircraft's pressure indicating systems.
Example Sentence 2
A blockage in the static line caused the pressure indicating systems to give erroneous altitude and airspeed information.