Which system primarily determines indicated airspeed in most aircraft?

Which system primarily determines indicated airspeed in most aircraft?

• A. Pitot-static system
• B. Static port
• C. GPS velocity
• D. Total temperature sensor

Answer: (A)

Indicated airspeed comes from the pitot-static system, which uses two pressures: the total (impact) pressure captured by the pitot tube and the ambient static pressure from the static ports. The airspeed indicator compares these pressures with a diaphragm or similar mechanism. As you fly faster, the dynamic pressure rises, pushing the diaphragm more and increasing the IAS readout. The static pressure provides the reference, but it’s the difference between the two that drives the indication. Since IAS is defined under standard atmosphere, changes in air density with altitude don’t change the reading, even though true airspeed would vary. The static port by itself doesn’t determine speed, GPS velocity gives groundspeed instead of airspeed, and the total temperature sensor is used to help compute true airspeed, not indicate it.

Indicated airspeed comes from the pitot-static system, which uses two pressures: the total (impact) pressure captured by the pitot tube and the ambient static pressure from the static ports. The airspeed indicator compares these pressures with a diaphragm or similar mechanism. As you fly faster, the dynamic pressure rises, pushing the diaphragm more and increasing the IAS readout. The static pressure provides the reference, but it’s the difference between the two that drives the indication. Since IAS is defined under standard atmosphere, changes in air density with altitude don’t change the reading, even though true airspeed would vary.

The static port by itself doesn’t determine speed, GPS velocity gives groundspeed instead of airspeed, and the total temperature sensor is used to help compute true airspeed, not indicate it.