In general aviation, it's almost ubiquitous that pilots yell "clear" or "clear prop" before engaging the starter. Are there any regulatory requirements to take this action either in the form of 14 CFR or maybe in the Airman Certification Standards?


3 Answers 3


Like @mongo, I am not aware of a regulation and don’t recall seeing anything about it in the AIM. However, the Airplane Flying Handbook (FAA-H-8083-3B) says this about engine start:

Prior to engine start, the pilot must ensure that the ramp area surrounding the airplane is clear of persons, equipment, and other hazards from coming into contact with the airplane or the propeller. Also, an awareness of what is behind the airplane prior to engine start is standard practice. A propeller or other engine thrust can produce substantial velocities, result in damage to property, and injure those on the ground. The hazard of debris being blown into persons or property must be mitigated by the pilot. At all times before engine start, the anti-collision lights should be turned on. For night operations, the position (navigation) lights should also be on. Finally, just prior to starter engagement, the pilot should always call “CLEAR” out of the side window and wait for a response from anyone who may be nearby before engaging the starter.

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    $\begingroup$ Note the difference between "must" and "should". $\endgroup$
    – user
    May 22, 2017 at 7:35
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    $\begingroup$ @MichaelKjörling: There's an RFC for that! Note that the RFC is software-related, not aviation related, and the FAA or other aviation regulatory bodies may have different definitions. $\endgroup$
    – dotancohen
    May 22, 2017 at 10:39
  • $\begingroup$ @dotancohen Yes, RFC 2119 is normatively cited by almost every RFC following it that even attempts to be normative. Of course, as you say, it's not really aviation-related. Still, I think the difference between the terms even in the quoted snippet is worth calling out. $\endgroup$
    – user
    May 22, 2017 at 10:46
  • $\begingroup$ Must, should, and shall is a mess. Don't use should or shall. One of the most ignored guidelines in the Federal government. plainlanguage.gov/howto/guidelines/bigdoc/writeMust.cfm $\endgroup$ May 22, 2017 at 14:51
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    $\begingroup$ "And wait" is important. I've seen pilots turn the key almost simultaneously with yelling "clear." Probably the same people who, when driving, turn on their blinker only after they start changing lanes. $\endgroup$ May 22, 2017 at 16:44

To my knowledge it is not a regulatory requirement. Assuring that there are no people or objects near the propellers is a regulatory matter.

Good practice is to call out, and then clear the area visually. Leave enough time for the line boy to get out from under the plane who you didn't notice clearing the chocks. (grin)

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    $\begingroup$ Said otherwise: The requirement is to ensure there are no people or objects around, yelling "Clear" is the usual method to meet the requirement. $\endgroup$
    – mins
    May 22, 2017 at 4:52
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    $\begingroup$ Eyes are your best tool. In larger turboprops I have flown, yelling clear is not done. On a noisy ramp, few might hear it. (Of course a turbo prop does not immediately start turning at idle RPM, so getting out of the way might be easier.) Some aircraft are pressurized, and having an open window might be a little more difficult. The best method is to have a ground observer to assist and indicate that the engine(s) are clear for starting. $\endgroup$
    – mongo
    May 22, 2017 at 5:19

There’s no regulation for yelling that out, save, I suppose that one could cite a flight crewmember under §91.13 guidelines for careless and reckless operation, if they attempted to start an aircraft engine with personnel nearby without giving proper warning to alert bystanders of the hazard. It is operating the aircraft in a careless or reckless manner that would endanger the life or property of another.

Many aircrews do not yell that out during commercial operations, but, in general, these are occurring on sterile ramps with trained personnel nearby. You are, in these situations, still responsible to be cognizant of the whereabouts of ground personnel and refrain from starting up or moving if they are near the aircraft.

That being said, if you are acting as PIC, you are directly responsible for, and the final authority on, the operation of that aircraft (§91.3). Should someone be injured or killed by a propstrike from an aircraft you are acting as PIC of during startup or taxi, and it’s determined that the cause of the accident is a result of your gross negligence, you could potentially be charged with criminal vehicular homicide and definitely face the prospect of a civil tort for wrongful death.


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