This struck me as a bit strange, 91.21 which covers electronic devices that can be used during IFR flight has some exceptions, one through three make logical sense (not really sure why portable voice recorders are in there though) but number 4, Electric Shavers, is specifically permitted by the regulation. Are that many people shaving under IFR conditions that this needed to be permitted? Is there some historical or practical reason why electric shavers are specifically named in this regulation?

§ 91.21 Portable electronic devices.

(a) Except as provided in paragraph (b) of this section, no person may operate, nor may any operator or pilot in command of an aircraft allow the operation of, any portable electronic device on any of the following U.S.-registered civil aircraft:

(1)Aircraft operated by a holder of an air carrier operating certificate or an operating certificate; or

(2) Any other aircraft while it is operated under IFR.

(b)Paragraph (a) of this section does not apply to -

(1) Portable voice recorders;

(2) Hearing aids;

(3) Heart pacemakers;

(4) Electric shavers; or

(5) Any other portable electronic device that the operator of the aircraft has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.

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    $\begingroup$ I'm willing to bet the reason is similar to why matches are allowed in carry-on baggage but you also need to strip and/or be groped at the security checkpoint. Security theatre. $\endgroup$ Commented Aug 15, 2019 at 15:02
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    $\begingroup$ I'm guessing it has to do with someone keen on grooming that used a razor in bumpy IMC because electric shavers we not permitted. $\endgroup$
    – user14897
    Commented Aug 15, 2019 at 15:12
  • $\begingroup$ The question, and the current answer, focus on the crew. Is it possible that this exception is really for the benefit of passengers? I'm imagining a businessman on a long flight who is meeting clients at the airport, taking a few minutes in the lavatory to freshen up and look his best. The other exemptions are also likely to be used by passengers. $\endgroup$ Commented Aug 16, 2019 at 14:56

1 Answer 1


This is an educated guess, based on history:

Electric razors were once well known as prone to generating elctromagnetic interference -- the ones available in the 1940s could pretty well blanket a nearby AM broadcast radio receiver.

However, in similar time frames, it was very important for oxygen masks to fit closely on the face, and beard stubble, besides being reportedly very uncomfortable, would compromise the seal (either increasing consumption from the limited store of oxygen available for high altitude flight, or risking hypoxia for the wearer). Therefore, on long flights, it wasn't at all uncommon for aircrew to shave one or more times before getting where they were going.

As noted in comments, shaving with a blade razor (even the safety razors available when this regulation has its roots) was a bit hazardous in an airplane that might, without any warning, encounter turbulence that could literally knock someone out of their seat if not belted in place. Wind-up rotary razors existed before 1950, but they were rare, relatively delicate, and expensive. Electric razors that ran on 115 V were available before 1940 and, with care, would do a good enough job to let an oxygen mask seal well (rechargeable types didn't appear until the late 1950s).

The regulation, then, is to recognize that even with the potential radio interference, an electric razor was specifically to be permitted during flight.

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    $\begingroup$ The must have expected long haul flights getting really long soon. $\endgroup$
    – Peter
    Commented Aug 15, 2019 at 18:48
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    $\begingroup$ The early commercial regs came out of military practice. B17 flights England-Germany-England ran long enough that a shave in flight wasn't a bad idea. Pressurization made this less important after the War, but once something is in the regs, it has to be shown to cause trouble to get it out. $\endgroup$
    – Zeiss Ikon
    Commented Aug 15, 2019 at 18:51
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    $\begingroup$ @Peter soon into the 1940s, like the Qantas "Double Sunrise" flight from Australia to India that took (as advertised) over 24 hours... $\endgroup$ Commented Aug 15, 2019 at 19:31
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    $\begingroup$ @Peter Some people grow stubble at 3x the rate others do. And with very stiff hairs a well. I shave a 2nd time before I go out for the night and need to look halfway presentable towards the end of the evening. If I only shave in the morning by midnight I look like most men that haven't shaved for 3 days. Funny thing is that it is mainly the stubble that grows fast. As the hairs get longer (more than about 1-2 mm) it slows down to normal hair-growth speed. $\endgroup$
    – Tonny
    Commented Aug 16, 2019 at 12:19
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    $\begingroup$ In early unpressurized aircraft, how would the crewmember be able to take their mask off long enough to shave? I can't hold my breath for that long! Did they bring the aircraft down to a lower altitude for a shave break? $\endgroup$
    – CCTO
    Commented Aug 16, 2019 at 14:20

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