ASA Aircraft Instrument Systems Practice Test 2026 – Complete All-in-One Guide for Exam Success!

The type of sensor commonly found in modern altimeters is pressure sensors with aneroid capsules. These sensors function by measuring atmospheric pressure, which decreases with altitude. The aneroid capsule is a sealed, flexible metal chamber that expands or contracts in response to changes in atmospheric pressure. As the aircraft ascends and the external pressure decreases, the capsule expands. Conversely, when the aircraft descends and the pressure increases, the capsule contracts. This movement is mechanically linked to the altimeter's pointer or electronic readout, providing an accurate indication of altitude.

Pressure sensors are highly reliable and have been widely adopted in aviation due to their straightforward design and consistent performance across various altitudes and weather conditions. Other sensor types, such as optical, radar, and magnetic sensors, do not typically serve this purpose in altimetry applications, making pressure sensors with aneroid capsules the definitive choice for measuring altitude in modern aircraft.