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There have already been some posts about pitot heaters: when to turn them on/off, why not leave them on etc. I don't want to go over that.

I am an engineer, so I'd like to ask: if the flight management avionics detect an out-of-bounds disagreement from the pitot transducers, and the heaters are off, why not turn them on, in addition to whatever other warnings etc. they already perform?

An ECAM message about turning on the heaters could be made and, if the pilot explicitly wants the heaters off for some reason, s/he can instruct the computer or pull a breaker, so overriding the software.

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    $\begingroup$ Are you thinking of the recent incident in Russia, which happened almost immediately after takeoff? While speculation about causes of accidents is off topic on Aviation SE, the phase of flight at the time of the accident can make a difference as to whether automatic pitot tube heating would even have time to work, even if it would correctly detect the situation as it was developing. $\endgroup$
    – user
    Commented Feb 13, 2018 at 21:33
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    $\begingroup$ This question is at least tangentially related as is this one $\endgroup$
    – Dave
    Commented Feb 13, 2018 at 21:44
  • $\begingroup$ IIRC the reverse is true on B737: The default is on. If it is off by whatever reason a ECAM message is displayed. The crew can react to that message however they like. $\endgroup$
    – kevin
    Commented Feb 14, 2018 at 1:09

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There's much simpler and safer logic. Most modern Western transport aircraft automatically switch the pitot heaters on when in flight mode or at least one engine is running. Pilots can manually force pitot heat on, but there's no direct option to switch them off. Normal procedure is to leave it in auto.

Boeings since the 757/767 are automatic (exception: 737), and Airbus has had it automatic since at least the A300-600. ERJ is auto, not sure about the CRJ200, but the 700 is auto.

Pitot heat indication systems are already required by certification standards. 14 CFR 25.1326:

If a flight instrument pitot heating system is installed, an indication system must be provided to indicate to the flight crew when that pitot heating system is not operating. The indication system must comply with the following requirements:

(a) The indication provided must incorporate an amber light that is in clear view of a flight crewmember.

(b) The indication provided must be designed to alert the flight crew if either of the following conditions exist:

(1) The pitot heating system is switched “off”.

(2) The pitot heating system is switched “on” and any pitot tube heating element is inoperative.

EASA CS 25.1326 is basically identical.

The Antonov 148 is certified to EASA CS-25, so it must have had such a warning system.

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  • $\begingroup$ Is this EASA reg why the DA40 with the G1000 always has an annunciation on when pitot heat is off or malfunctions? $\endgroup$
    – Pugz
    Commented Feb 14, 2018 at 2:16
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    $\begingroup$ @Pugz Similar. DA40 is a normal category plane, certified under JAR/CS-23 (Part 23 for those in the US), so the relevant regulation is CS 23.1326, which also reads nearly identical. $\endgroup$
    – user71659
    Commented Feb 14, 2018 at 2:19
  • $\begingroup$ is there a similar reg for the U.S. for normal category aircraft? $\endgroup$
    – Pugz
    Commented Feb 14, 2018 at 2:24
  • $\begingroup$ @Pugz 14 CFR 23.1326. It's been harmonized (harmonised)! $\endgroup$
    – user71659
    Commented Feb 14, 2018 at 2:26
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    $\begingroup$ @Pugz Citation says Feb. 9, 1996, as part of harmonization with JAR. I don't know if it existed in a different form prior. Note that it is only required if the pitot heat is required (due to IFR or flight in icing; Part 23.1323). Also, if the aircraft was certified on an older basis, it may be exempt. $\endgroup$
    – user71659
    Commented Feb 14, 2018 at 2:33

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