SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/ifr-pitot-both-blocked

Ice blocks a pitot tube's ram opening and its drain hole. What does the airspeed indicator do in a climb?

It acts like an altimeter, reading higher in a climb.

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  1. Acts like an altimeter, reading higher as you climb ✔
  2. Reads zero no matter what you do
  3. Reads lower as you climb

Why: With both holes plugged, the pressure trapped in the pitot line stays fixed while static pressure changes. So the ASI behaves like an altimeter, rising in a climb and falling in a descent.

Huh, didn't know that: If only the ram opening is blocked and the drain hole stays open, indicated airspeed slowly drops to zero.

The dad joke
My airspeed indicator froze at zero. It says it just needs a little space.
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References

Answer: Acts like an altimeter, reading higher as you climb. With both holes plugged, the pressure trapped in the pitot line stays fixed while static pressure changes. So the ASI behaves like an altimeter, rising in a climb and falling in a descent.

  1. FAA Instrument Flying Handbook (FAA-H-8083-15B) www.faa.gov/sites/faa.gov/files/pilots/FAA-H-8083-15B.pdf
    ASI operates like an altimeter as the aircraft climbs and descends.
    Checked 2026-10-11.

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Test yourself in the game

FlyingStatic ports block at 4,000 feet. You then climb well above that. How does the airspeed indicator read?FlyingStatic ports ice over at 5,000 feet and you climb to 7,000. What does the altimeter show?FlyingYour static system is blocked. What does the vertical speed indicator show while you climb?

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