Rounding up and down heading readings
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Rounding up and down heading readings
Hi,
When asked by ATC e.g "whatīs your present heading", I usually round up or down the figure e.g if itīs hdg 142, I would say hdg 140; likewiese hdg 143 would be rounded up to hdg 145. Furthermore, I never heard pilots or ATC stating a heading other than with a -0 or -5 at the end.
I am wondering, however, why doesnīt ATC need the exact heading or to put it another way, why rounding up or down to the nearest -5 or -0 is tolerated? What do you see on your radar screen?
Cheers
Cecco
When asked by ATC e.g "whatīs your present heading", I usually round up or down the figure e.g if itīs hdg 142, I would say hdg 140; likewiese hdg 143 would be rounded up to hdg 145. Furthermore, I never heard pilots or ATC stating a heading other than with a -0 or -5 at the end.
I am wondering, however, why doesnīt ATC need the exact heading or to put it another way, why rounding up or down to the nearest -5 or -0 is tolerated? What do you see on your radar screen?
Cheers
Cecco
When Atc ask for a present heading we'd probably usually prefer the exact heading. 2 instances where I'd usually ask what heading you're flying before vectoring are when I need to put someone on a parallel track or when I want to get the idea of what the wind is doing before I start vectoring.
A couple of degrees either way in both cases probably isn't a big issue, just depending in how specific you want to be.. Especially with parallel tracking, if you're heading 142 but say heading 140 and there's another aircraft 6 miles and converging and I give them heading 140 to parallell there might still be a bit of converging.
Atc generally give headings in 5s or 0s because that is about as specific as we need to be for sequencing. It's easier to say, easier to remember for the pilots, easier to read back correctly. Only time we'd really need to be more specific is if vectoring someone around a star/Sid
A couple of degrees either way in both cases probably isn't a big issue, just depending in how specific you want to be.. Especially with parallel tracking, if you're heading 142 but say heading 140 and there's another aircraft 6 miles and converging and I give them heading 140 to parallell there might still be a bit of converging.
Atc generally give headings in 5s or 0s because that is about as specific as we need to be for sequencing. It's easier to say, easier to remember for the pilots, easier to read back correctly. Only time we'd really need to be more specific is if vectoring someone around a star/Sid
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We don't give headings other than 0 or 5 because it's less difficult to have a misunderstanding with only two possibilities.
At my centre we see the downlinked Mode S heading so we know what it should be after an instruction to turn 10 degrees.
This also means that anyone rounding up or down gets "caught". Rounding bugs me. If I wanted the aircraft on a particular heading I would have said. If I want the aircraft to turn 5 degrees left then I want it 5 degrees left.
At my centre we see the downlinked Mode S heading so we know what it should be after an instruction to turn 10 degrees.
This also means that anyone rounding up or down gets "caught". Rounding bugs me. If I wanted the aircraft on a particular heading I would have said. If I want the aircraft to turn 5 degrees left then I want it 5 degrees left.
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I have a feeling that it is more to do with historical reasons. When hand flying an aircraft it is (was) easier to fly headings in multiples of five. Nothing to do with piloting skills, but more to do with how the compass is marked (the 5th and 10th degree tended to have a thicker marking than the individual degrees). Especially relevant if flying on standby instruments.
Having said that, in the military where (I assume) there is more practice and currency in manual flying than on civvy street, then the use of intermediate headings, especially on a PAR, was given. Even then though, for changes of one degree it used to be the norm that you would be told to turn left 3 degrees, then turn right 2 degrees, to get a one degree left adjustment.
Re above regarding reciprocal headings for separation... if you're worried that a one or two degree anomaly is going to give you convergence on aircraft 6 miles apart head to head, then you are cutting it a bit fine with your separation anyways and I'd suggest that on radar no one is that good at judging distances...
Nowadays, you can tell a pilot to fly a heading of 141 degrees and he turns the knob to that heading...
Having said that, in the military where (I assume) there is more practice and currency in manual flying than on civvy street, then the use of intermediate headings, especially on a PAR, was given. Even then though, for changes of one degree it used to be the norm that you would be told to turn left 3 degrees, then turn right 2 degrees, to get a one degree left adjustment.
Re above regarding reciprocal headings for separation... if you're worried that a one or two degree anomaly is going to give you convergence on aircraft 6 miles apart head to head, then you are cutting it a bit fine with your separation anyways and I'd suggest that on radar no one is that good at judging distances...
Nowadays, you can tell a pilot to fly a heading of 141 degrees and he turns the knob to that heading...
Last edited by anotherthing; 14th Sep 2013 at 07:19.
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If I'm on a heading of 133 and told to turn e.g ten degrees to the right, I will turn on heading 143. However, when asked by the next sector what heading I am on, I would tell him hdg 145. It's not that I turn by 12 degrees to reach a -5 or -0 but the figure I forward.
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Personally as a UK approach radar controller, when I ask you to report heading or to turn by a certain amount of degrees and then report the heading, I would be happy for you to adjust the heading to the nearest 5 degrees and report that.
e.g.
You are flying on the STAR, heading is 353. I ask you to turn right 10 degrees and report the heading. I would be happy for you to both turn to and report a heading of 005.
e.g.
You are flying on the STAR, heading is 353. I ask you to turn right 10 degrees and report the heading. I would be happy for you to both turn to and report a heading of 005.
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Anotherthing:
I will fully agree with you on this, however not too sure that the newbies now working with iFacts that have never used any other method would consider this a problem.......
Re above regarding reciprocal headings for separation... if you're worried that a one or two degree anomaly is going to give you convergence on aircraft 6 miles apart head to head, then you are cutting it a bit fine with your separation anyways and I'd suggest that on radar no one is that good at judging distances...
I have recently stopped informing ATC of the new heading when given an instruction to turn a number of degrees, on the basis that they can see it on the Mode S readout and I don't see the point in clogging the airwaves. Fair enough?
But I would never round up or down a specific heading instruction. In the majority of situations it might not matter, but occasionally it might and anyway I'm lazy - lying would involve having to reach up and change the heading bug on the MCP!
But I would never round up or down a specific heading instruction. In the majority of situations it might not matter, but occasionally it might and anyway I'm lazy - lying would involve having to reach up and change the heading bug on the MCP!
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Originally Posted by Mikehotel152
I have recently stopped informing ATC of the new heading when given an instruction to turn a number of degrees, on the basis that they can see it on the Mode S readout and I don't see the point in clogging the airwaves. Fair enough?
When they want it they specifically ask for it: " turn right ten degrees - report that heading."
These memes get picked up and recycled but it don't make them right.
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If a pilot is asked for a heading, giving it exactly or to the nearest five degrees will make little difference.
Personally, with Mode S available, I normally never ask for it. I can either just ask you to turn a number of degrees (and won't ask you to report new heading as I can see what it is if I need to), or I can do the maths and turn you on to a specific heading. Cuts down RT and superfluous info.
If you don't have Mode S or are out of cover of a Mode S radar, I would ask you to report your existing or new heading but only if I need to know it.
Personally, with Mode S available, I normally never ask for it. I can either just ask you to turn a number of degrees (and won't ask you to report new heading as I can see what it is if I need to), or I can do the maths and turn you on to a specific heading. Cuts down RT and superfluous info.
If you don't have Mode S or are out of cover of a Mode S radar, I would ask you to report your existing or new heading but only if I need to know it.
