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Why might flight schools prohibit you from testing pitot heat during pre-flight? I know of a school in Texas that has this policy but don’t understand why.

Here is a snippet of the C172 AFM which lists testing pitot heat for normal pre-flight procedures. The aircraft is not ice legal anyways but still seems like a good idea if you (although unlikely in the region) inadvertently enter icing conditions.

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    $\begingroup$ Why were the comments deleted?? $\endgroup$
    – John K
    Dec 9, 2021 at 16:49
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    $\begingroup$ @JohnK I have the same question. I've noted two other of my comments (in addition to one here) from two different recent questions were also deleted. I'm aware about the policy on comments and all three of my recently deleted comments were appropriate. $\endgroup$
    – 757toga
    Dec 9, 2021 at 19:06
  • $\begingroup$ ++1 to that. I found the comments supplementing the question effectively! $\endgroup$
    – TayE
    Dec 9, 2021 at 22:20
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    $\begingroup$ Comments seeking clarification, where clarification had been given (and updated into question) were no longer necessary. Comments which are pseudo answers were removed as per policy see also this meta question. Conversation is better suited to chat $\endgroup$
    – Jamiec
    Dec 11, 2021 at 9:25

1 Answer 1

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I was taught to check it (on a C152/172) before every flight but I've also heard people say that you don't need to. Some reasons I've heard people give for not checking it are:

  1. Risk of draining the battery to the point where you can't start the engine
  2. Risk of burning your hand on the pitot
  3. Risk of forgetting to remove the pitot cover and melting it onto the tube
  4. The POH doesn't include it in the preflight checks so it can't be important

Note that you can avoid most of those issues by using a checklist.

You can check what the POH says, e.g. the C172S POH includes it in the preflight but the C172M one doesn't. But even if the POH doesn't mention it, you should always check it before operating in IMC.

It would be a great question to ask the school or an instructor there, especially if the aircraft's POH does say you should check it.

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    $\begingroup$ I'd think the last paragraph is the key item. If the school is contradicting the POH, it's up to them to explain why. $\endgroup$
    – FreeMan
    Dec 9, 2021 at 17:07
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    $\begingroup$ In the 1976 C172 M model it does say that if you have an inadvertent icing encounter you should turn the pitot heat on. But, of course, if you don't check its operation prior to takeoff you can't be certain it will work. The checklist only says to check that the pitot tube is not blocked. $\endgroup$
    – 757toga
    Dec 9, 2021 at 20:34
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    $\begingroup$ @757toga, I've seen a video of crossing I think Canada to Greenland in a C210 where their pitot clogged up in VMC with fairly good visibility (I think they were above layer of clouds, but it was clear at their level). Turning on the pitot heat fixed it after a while. So clearly the pitot can pick up some ice even in what isn't otherwise considered icing conditions. $\endgroup$
    – Jan Hudec
    Dec 9, 2021 at 22:15
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    $\begingroup$ @JanHudec, I totally agree with you. Any aircraft that does not have a passive operational system that continually monitors the status of the pitot tube(s) should have a checklist requirement for a preflight check. It's a critical component (heat) and needs to be operational when needed. $\endgroup$
    – 757toga
    Dec 9, 2021 at 23:20
  • $\begingroup$ This is a fantastic, complete answer. The primary reason is to avoid accidentally running the battery down when a student forgets to turn the master and pitot heat switch off, because this grounds the airplane for hours, cancelling numerous scheduled flights. For a flight school in Texas, icing is not likely, particularly if they only do VFR Private training and no IMC. In my opinion, the checklist should read: Pitot Heat: CHECK if flying IMC (or if OAT at planned cruise altitude is below 10C/41F). It is SO easy for a CFI to train a student to never leave the master or pitot on though... $\endgroup$ Dec 10, 2021 at 21:52

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