By all definitions that my team and I have found, fly-by and short-turn (with respect to military unmanned air vehicle waypoint based flight) mean the same thing. Briefly, this allows the pilot to fly within a capture distance of the waypoint but is not required to fly directly over or through it. In other words, the pilot can start turning before the waypoint is reached.

Current Definition: A short turn will be performed at the turn location. A short turn indicates that the vehicle may begin its turn prior to reaching the waypoint and fly-by it instead of through or over it.

Is there any nuanced difference between these two states so that I might further clarify this in my definition?

  • 2
    $\begingroup$ Is this related to RNAV? RNAV defines two waypoint types: Fly-Over and Fly-By. I've never heard the term short-turn. In fact, googling "short turn" waypoint gives this question as first result. $\endgroup$
    – DeltaLima
    Jan 13 '15 at 19:29
  • $\begingroup$ @DeltaLima Perhaps, but this relates to military aviation, especially with respect to unmanned aerial vehicles. $\endgroup$
    – Chris
    Jan 13 '15 at 19:32
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    $\begingroup$ Please edit the question to define context. This way it's rather ambiguous. $\endgroup$
    – Jan Hudec
    Jan 13 '15 at 19:35
  • $\begingroup$ What do you mean by the current definition? Is that your definition, or is that a definition you have from some reference. $\endgroup$
    – DeltaLima
    Jan 13 '15 at 19:40
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    $\begingroup$ I would drop the term short turn and only use Fly-By and Fly-Over in combination with fix or waypoint. A fly-by waypoint means that the pilot (or autoflight system) will anticipate the turn and therefore starts the turn before reaching the waypoint. When using a fly-over waypoint, the turn will not start before the aircraft has flown directly over the waypoint. $\endgroup$
    – DeltaLima
    Jan 13 '15 at 19:49

The context of your question is a bit unclear, but assuming that you're asking about navigation waypoints in the US then you're probably referring to these terms as defined in the FAA's Pilot/Controller Glossary:

FLY-BY WAYPOINT- A fly-by waypoint requires the use of turn anticipation to avoid overshoot of the next flight segment.

FLY-OVER WAYPOINT- A fly-over waypoint precludes any turn until the waypoint is overflown and is followed by an intercept maneuver of the next flight segment.

As per the comments, I have never heard of a "short turn" waypoint and it isn't in the P/CG.

  • $\begingroup$ Maybe add something about the role of lead-in radials on DME arcs? $\endgroup$
    – rbp
    Jan 14 '15 at 0:09
  • $\begingroup$ @rbp I could but it doesn't seem directly relevant here: the question as I understand it is about the terminology of waypoints rather than the concept or purpose of leading a turn in general $\endgroup$
    – Pondlife
    Jan 14 '15 at 13:59
  • $\begingroup$ Check out the LOMMA waypoint. It's a flyby because of the lead-in radial. terps.com/ifrr/may96.pdf $\endgroup$
    – rbp
    Jan 14 '15 at 21:27

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