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Subject: Re: course, heading, track
From: Trevor Kenchington (Gadus@XXX.XXX)
Date: Thu Feb 07 2002 - 08:04:51 EST
Paul Hirose wrote:
> I think you were incorrect to contradict John LeRoy. His message was
> obviously in the context of flying. Aviators (at least in the U.S.)
> don't use the Bowditch meaning for some of those navigational words.
Perhaps you are right and if so, I owe John an apology.
I don't claim any knowledge of the navigation terminology of aviators.
However, if John was seeking to draw a distinction between that and
Bowditch-like terminology, his intention was not clear to me. [He wrote
"course was never path through the air, for instance" in response to
Nigel Gardner's "Course was path through the air or water" -- the "for
instance" implying, to me, that John was suggesting that the course is
not the path through either fluid medium. (Much more dissection of
wording and this thread will be even further lost in the intricacies of
English grammar than it is in those of navigational terms!]
> In aviation, "course" means the intended direction of flight over the
> ground.
> A heading is always a direction measured with respect
> to the longitudinal axis of the airplane, or in other words, the
> direction in which the airplane is pointed
> "TRACK - The actual flight path of an aircraft over the surface of the
> earth."
So, if I understand that correctly, U.S. aviation terminology does not
distinguish between what we surface-bound types call "heading" and
"course". Are aircraft so stable in yaw that the distinction is not needed?
Then "course" is used in the air for what would be "track" on the water,
while the aviator's "track" approximates to the surface navigator's
"course made good" -- though the latter is viewed as a straight line
from point to point, whereas the aviator's "track" appears from the
above definition to include whatever random movements about that line
the aircraft makes (small for a high-flying jet but presumably not for a
low-powered light aircraft at low altitude).
It must be tough for Navy aviators, navigating their aircraft by one
terminology while their floating runways move about following a
different one!
Trevor Kenchington
-- Trevor J. Kenchington PhD Gadus@XXX.XXX Gadus Associates, Office(902) 889-9250 R.R.#1, Musquodoboit Harbour, Fax (902) 889-9251 Nova Scotia B0J 2L0, CANADA Home (902) 889-3555Science Serving the Fisheries http://home.istar.ca/~gadus
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