own navigation definition
Why do it if it's not fun?
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Can I throw some more fuel on the fire, please?
I'm an instructor. Although my aircraft are fitted with GPS, I frequently won't allow my students to use it (because the test requires them to be able to navigate without it). In this case, the easiest way of navigating to a point, where the point is defined as a radial/distance from a VOR/DME, is to intercept the radial, then track the radial until arriving at the correct distance.
What I teach my students (and I've always believed to be correct) is this:
- If instructed to go "Direct" to a point, then, if I'm letting you use GPS, use the "Direct To" button. If I'm not letting you use GPS, then use your situational awareness to have a best guess at a sensible heading to go direct to that point. As you get closer, you can assess whether the radial and the DME distance are going to reach their targets together (i.e. if you're on track), and adjust the heading if necessary. If you're really not sure, ask the controller for a QDM to the point you're going to.
- If told "own navigation" to a point (without the word "direct), then you can follow any sensible route to that point, and this will normally (especially if I'm not letting you use GPS) involve intercepting the correct radial from the VOR, then following that radial until reaching the DME distance.
After reading this thread, I (still) think this is correct, but since the comments are geared to airliners which can always go Direct To, perhaps someone could confirm this?
FFF
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I'm an instructor. Although my aircraft are fitted with GPS, I frequently won't allow my students to use it (because the test requires them to be able to navigate without it). In this case, the easiest way of navigating to a point, where the point is defined as a radial/distance from a VOR/DME, is to intercept the radial, then track the radial until arriving at the correct distance.
What I teach my students (and I've always believed to be correct) is this:
- If instructed to go "Direct" to a point, then, if I'm letting you use GPS, use the "Direct To" button. If I'm not letting you use GPS, then use your situational awareness to have a best guess at a sensible heading to go direct to that point. As you get closer, you can assess whether the radial and the DME distance are going to reach their targets together (i.e. if you're on track), and adjust the heading if necessary. If you're really not sure, ask the controller for a QDM to the point you're going to.
- If told "own navigation" to a point (without the word "direct), then you can follow any sensible route to that point, and this will normally (especially if I'm not letting you use GPS) involve intercepting the correct radial from the VOR, then following that radial until reaching the DME distance.
After reading this thread, I (still) think this is correct, but since the comments are geared to airliners which can always go Direct To, perhaps someone could confirm this?
FFF
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Tin Pusher,
Direct is quite simple, your right on that. But as Spitoon has already pointed out, by virtue of the fact that this thread continues, its context can confuse when not used in isolation... Hence my earlier question:
Why bother preceeding the instruction 'direct' with '...own nav...'? There MAY be a contradiction. If direct is as simple as you and I and the rest of the aviation world agree, why complicate it by using it in conjuction with own nav when the two may not go hand in hand and the phrase is clearly confusing pilots. If you want the pilot to navigate to a point, instruct them so. If you want them to go direct somewhere, instruct them so.
As FlyingforFun has just pointed out, OWN NAV MAY not take the a/c DIRECT to said point.
Defining each word individually may not solve the confusion associated with this issue.
CR
Direct is quite simple, your right on that. But as Spitoon has already pointed out, by virtue of the fact that this thread continues, its context can confuse when not used in isolation... Hence my earlier question:
Why bother preceeding the instruction 'direct' with '...own nav...'? There MAY be a contradiction. If direct is as simple as you and I and the rest of the aviation world agree, why complicate it by using it in conjuction with own nav when the two may not go hand in hand and the phrase is clearly confusing pilots. If you want the pilot to navigate to a point, instruct them so. If you want them to go direct somewhere, instruct them so.
As FlyingforFun has just pointed out, OWN NAV MAY not take the a/c DIRECT to said point.
Defining each word individually may not solve the confusion associated with this issue.
CR
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fourthreethree may be jaw agape because others have the temerity to have a different interpretation of a bit of phraseology/procedure
Which is why I am amazed to see how people in my profession believe its fine for a pilot to fly however he pleases when he has been given a clearance direct to a navigation point. I had a scenario several years back when a pilot under this impression decided to turn to give his passengers a nice view of the coastline, and turned into an exersize area occupied by around twelve F-16's simulating air to air combat quite close to the airway. This is NOT ok!!!!
I am not disputing the intention of the initial post, the best way to get an answer to a question is to ask it. But the thread seems to have got lost in the definition of "own navigation" rather than the use of the word "direct".
"XYZ123 resume own navigation direct ABC" after XYZ123 was locked on a radar heading is a clearance, to deviate from that clearance requires approval from ATC.
TinPusher.....spot on.
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Originally Posted by 433
...the thread seems to have got lost in the definition of "own navigation" rather than the use of the word "direct".
As long as the word 'direct' is used I agree the pilot should follow the shortest line to the fix - nowadays sometimes we need to think great circle which raises some other issues, but essentially direct means straight line to wherever is specified.
But 'own nav', without specifying direct or a particular point, means different things to different people and some of the interpretations are surprising...and interesting. I doubt that we will see an internationally agreed meaning for 'own nav' in specific situations any time soon. So, for me, the really interesting part about this thread is just how important it is to use unambiguous clearances - i.e. to state direct and to where when I mean direct and to be very wary of clearing an aircraft on own nav if I'm not going to be able to keep a careful eye on it (=very rarely!).
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Further to my previous, quote from tp;
'It's very simple really, DIRECT XXX is just that. Own Nav is a standard intercept of track to XXX',
so by your definition, when you give the intruction '...own nav dct XXX' do you expect the pilot to fly directly to the standard intercept (30deg) point or straight to xxx. Your 'my last post' post doesn't clarify either.
I agree with 433 about unambiguous phraseolodgy which is why I don't use 'own nav dct'. I don't ever remember being taught to use it and I never will (unless all this is beautifully resolved) because imho it seems unclear and apparently so do many pilots. After radar headings '...resume own nav xxx'...', yes. '... route direct xxx...', yes. '...turn left/right dct xxx.', yes. '... own nav dct xxx', no.
I except that it is commonly used and rarely causes confusion but this thread is questioning its meaning and as yet it seems unresolved. The point is it COULD be interpreted incorrectly by a pilot and so needs to be addressed.
It would be interesting to see if, in general, ATCO's of certain nationalities use this phrase whilst other nationalities don't? Any comments?
Awaiting THE answer and more than happy to be enlightened.
'It's very simple really, DIRECT XXX is just that. Own Nav is a standard intercept of track to XXX',
so by your definition, when you give the intruction '...own nav dct XXX' do you expect the pilot to fly directly to the standard intercept (30deg) point or straight to xxx. Your 'my last post' post doesn't clarify either.
I agree with 433 about unambiguous phraseolodgy which is why I don't use 'own nav dct'. I don't ever remember being taught to use it and I never will (unless all this is beautifully resolved) because imho it seems unclear and apparently so do many pilots. After radar headings '...resume own nav xxx'...', yes. '... route direct xxx...', yes. '...turn left/right dct xxx.', yes. '... own nav dct xxx', no.
I except that it is commonly used and rarely causes confusion but this thread is questioning its meaning and as yet it seems unresolved. The point is it COULD be interpreted incorrectly by a pilot and so needs to be addressed.
It would be interesting to see if, in general, ATCO's of certain nationalities use this phrase whilst other nationalities don't? Any comments?
Awaiting THE answer and more than happy to be enlightened.
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If in RNAV airspace then the aircraft is RNAV equipped and when cleared direct to xxx then their "normal navigation" will be to route from present position direct to that point and they will perform to the required RNP.
If in non-RNAV airspace or if the RNAV has failed then the radar controller should provide magnetic track to the waypoint when vectoring is complete and since they are by definition required to monitor the flight can provide additional guidance if required.
If procedural, then you will not be asking this question.
Spitoon,
You don't have to worry about Great Circle because aircraft following airways have always been following great circles because that is what radio signals always follow. Over a distance such as STU to DVR the difference between great circle and rhumb line is minimal at the mid point.
Regards,
DFC
If in non-RNAV airspace or if the RNAV has failed then the radar controller should provide magnetic track to the waypoint when vectoring is complete and since they are by definition required to monitor the flight can provide additional guidance if required.
If procedural, then you will not be asking this question.
Spitoon,
You don't have to worry about Great Circle because aircraft following airways have always been following great circles because that is what radio signals always follow. Over a distance such as STU to DVR the difference between great circle and rhumb line is minimal at the mid point.
Regards,
DFC
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If procedural, then you will not be asking this question.
And I agree, that "own nav ABC" clears the crew for maneuvers convenient to them, not limited to proceeding "direct".
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DFC, thanks for your reassurance but with the possibility for an aircraft to route from, say, over the UK midlands direct to Brindisi, ATC co-ordination based on the conventional route structure is not easy - and the difference between great circle and rhumb line may no longer be insignificant.
As for the procedural situation, one of the ways that capacity increases are expected to be achieved is by the use RNAV-defined routes that may not be radar monitored. Other plans are for closely-spaced RNAV-defined routes where it is unlikely that in the worst case scenario a controller, even if he/she happens to be watching the traffic pair closely at the apposite moment, will have time to do anything if an aircraft deviates from the prescribed route (so, one argument goes, why bother with the controller?).
As for the procedural situation, one of the ways that capacity increases are expected to be achieved is by the use RNAV-defined routes that may not be radar monitored. Other plans are for closely-spaced RNAV-defined routes where it is unlikely that in the worst case scenario a controller, even if he/she happens to be watching the traffic pair closely at the apposite moment, will have time to do anything if an aircraft deviates from the prescribed route (so, one argument goes, why bother with the controller?).
I frequently request IFR transit through a local CTA enroute A - B and am invariably cleared but to expect vectors to co-ordinate traffic. When out of their hair I am usually cleared "resume own nav" and bimble on to my waypoint.
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direct is DIRECT
Direct means Direct -- All ATC has done is tell you that you are no longer on an ATC assigned heading. If you are on a WX deviation then US ATC may tell you "cleared direct (fix) when clear of weather". Then it is up to you to decide when that is appropriate. U.S. ATC may also ask the pilot to "advise when able to proceed on course" or "advise when clear of weather" and then issue a reroute clearance.
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Ok...my last last post on this thread
so by your definition, when you give the intruction '...own nav dct XXX' do you expect the pilot to fly directly to the standard intercept (30deg) point or straight to xxx. Your 'my last post' post doesn't clarify either.
sorry mate but at the risk of repeating myself " DIRECT XXX means just that!! Go DIRECTLY to point XXX, do NOT pass go and do NOT collect $200!!
If I don't say DIRECT then make a standard intercept of track.
My understanding is that the phrase 'resume own nav' is formally notifying the pilot that I am no longer providing vectors and the responsibility for nav now rests with the pilot, I think Ferris summed that up quite well.
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If I tell you to "Deviate as required" please do not tell me or ask me about all your turns that you want to make,you are wasting RT space-I already told you that you can do it!!
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The only guidance I have read recently tells me that "Resume own navigation..." means that "ATC expect the crew to regain the flight planned/cleared route as soon as possible, NOT BYPASSING ANY INTERMEDIATE FIXES" (my bold).
Furthermore, I'm instructed that "Resume own navigation direct to ..." means that "ATC expect the crew... to fly direct to that fix". The exception being Latin America where the term "direct" means "proceed along the flight planned route without delay".
I don't fly to Latin America, so I can't comment on the last part and I disagree with the given interpretation of "resume own navigation" and I've never seen anyone apply it in that way.
G W-H
Furthermore, I'm instructed that "Resume own navigation direct to ..." means that "ATC expect the crew... to fly direct to that fix". The exception being Latin America where the term "direct" means "proceed along the flight planned route without delay".
I don't fly to Latin America, so I can't comment on the last part and I disagree with the given interpretation of "resume own navigation" and I've never seen anyone apply it in that way.
G W-H
