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I am studying a text entitled Unmanned Aircraft Systems. How can we simplify the instruction in quotes so that it is more understandable and can be understood by a nontechnical. Please note I am not seeking to know all technical jargon of routing aircraft, rather to get what a pilot is told with this instruction to do.

Ideally, the communication process includes three parts: the initial call, readback, and hearback. For example, an ATCO would issue an instruction “American 755, turn right, heading 320.” Pilots onboard the aircraft would respond, or readback the message “Right, heading 320, American 755.”

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It is quite simple if you look into the answer linked by Steve V. to understand what the headings are. Here is a simple example: aircraft flies at 290. Controller instructs right turn to 320. The image below shows how should the aircraft turn. Heading is on top and on the orange "bug". (Needle shows track but you can safely ignore it for this example).

Short turn

But here is a subtle case: if the aircraft flies on a heading of let's say 030 and the crew is instructed to turn right heading 320, then they should perform a 290 degrees turn to the right to meet heading 320.

Long turn

This might not be obvious at first sight as it seems awkward, but it's critical in air traffic control.

Notes for the images: Compass is set to show "head up" ie the current heading of the aircraft on top and not "north up". Also the compass rose for brevity does not depict degrees but tens of degrees. So "15" stands for 150 degrees. Images source: own work.

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  • $\begingroup$ Yeah it is confusing, I cannot match it with trigonometric circle or a simple watch. I might need to do some study on Wikipedia about this. $\endgroup$ – codezombie Sep 20 '15 at 22:37
  • $\begingroup$ @JasonStack May I ask what is confusing? Bear in mind that in trigonometric circle, angle increases counterclockwise while in a compass heading increases clockwise. $\endgroup$ – Stelios Adamantidis Sep 20 '15 at 22:41
  • $\begingroup$ Ok, how many degrees are there in the circle in total and why doesn't 0 start from a position corresponding to North (clock 0)? $\endgroup$ – codezombie Sep 20 '15 at 22:43
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    $\begingroup$ @JasonStack 360 degrees and 0 is not on top because compass is set to "head up" not "north up". Actually I will incorporate that last part in the answer. $\endgroup$ – Stelios Adamantidis Sep 20 '15 at 22:45
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    $\begingroup$ @JasonStack - in both illustrations, look for the 0: that's pointing North. There are 360 degrees in the circle, but the compass shows only the first two digits. So 27 is 270 degrees from North, i.e., West. The compass is showing the plane's heading at the top. The first one, for example, shows a plane whose heading is 290 degrees: that's the 290 at the top of the circle. Doing it that way makes it easier to picture what's going on, once you've gotten used to it. $\endgroup$ – Pete Becker Sep 21 '15 at 13:17
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American 755, turn right, heading 320.

Aviation phraseology is direct, specific, and concise. The three items here:

  • The controller is instructing the aircraft identified as American 755
  • to make a right turn
  • such that they maintain a heading (direction) of 320 degrees (5 degrees north of north-west).

Though you may not be interested right now, at some level you might have to get technical, as communication involves defining terms :)

In case you are interested, for references and further reading see this page from the FAA. Especially of note:

  • Pilot/Controller Glossary - contains definitions for radio communications.
  • Aeronautical Information Manual - contains instructions for pilots.
  • JO 7110.65 - (more technical) the handbook for controllers. Everything they say should be in there.
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  • $\begingroup$ It is worth noting that heading means a direction the aircraft is to point (along the aircraft longitudinal axis) relative to the magnetic compass as opposed to: a "true" heading relative to geographical north; a direction the aircraft is to track; or a course to be flown. The differences are important and may not be obvious to those not in the know. $\endgroup$ – J Walters Mar 24 '17 at 16:49
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The basic answer is that the controller is instructing American 755 to turn right in order to point the airplane a direction which is 320 degrees clockwise from due north (basically northwest)

For the specifics of what a "heading" is, see this excellent answer (with pictures!).

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'American' is the callsign of American Airlines and '755' is the flight number.Here the plane is being intructed by the Air Traffic Control to make a right turn until they are pointing towards the 320 degrees mark on their heading indicator or the compass.

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    $\begingroup$ It doesn't add to the already numerous answers, is it? $\endgroup$ – mins Mar 24 '17 at 17:36

protected by Ralph J Mar 24 '17 at 16:54

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