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I am a private pilot from Argentina studying to become a commercial pilot. In one of the books I was given to study, published by the Chilean air force, the there's a claim (in Spanish, page 36) that aircraft weight influences the installation error in a pitot-static system.

To me, this is counter-intuitive as I would think the weight of the aircraft should have no effect on the airflow around the pressure sensors outside the aircraft (pitot tube and static port). The only possible way I would think aircraft weight would have an effect on installation error, is if this weight implies a change in shape which in turn affects airflow, but I'm not sure this is the case.

I was able to track that statement back to where it was (probably) taken from, which is on this old website from FIU (partially funded by NASA), but no further, and I wasn't able to find any other source whatsoever mentioning weight as a factor.

If it's not mentioned anywhere else, it's probably not that important, but I want to know if I should adjust my mental model on the physics sorrounding how these measurements are made.

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At a given speed, the lighter aircraft will have a lower Angle of Attack than the heavier one, so at an actual 200 knots (and level flight), the indicated airspeed will have more effects from the AoA (i.e. the pitot tube not aligned directly into the relative wind) with the heavier aircraft.

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  • $\begingroup$ So it's not weight per se causing the measurement difference, but its influence on the AoA... so it's more of an indirect effect. That makes more sense, thanks. $\endgroup$ Dec 18, 2023 at 12:23

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