own navigation definition
 

What does the phrase

"Own navigation direct xxx" actually mean (in IFR controlled air space)

Was recently flying under this instruction and needed to request a 20 degree left or right to avoid wx. When I requested it, I was told that I was under my own nav so could do as I pleased. Subsrequent discussions in the crew room have revealed that basically no one understands the instruction (10 different answers from 10 different pilots),

Can anyone enlighten us??

You are basically making your own way to the waypoint, how you get there is up to you, so a left or right turn to avoid weather is not a problem , you would only need to request it if you were doing anything other than flying own navigation (i.e on a specified heading, or on flight plan route)

A call to ATC wouldn't go amiss though, just to keep us in the loop. If we have sent you direct to a point & we see you heading in a different direction to that point then we are going to query where you are heading, just incase you mis-heard the waypoint or had a bit of finger trouble.

So direct XXX means 'get there how you like' huh?????
 

"Means just that! I have finished vectoring and now it is up to you to navigate your way as it pleases you, as long as it is DIRECT to point XXX.
Sorry but I have to disagree. A turn certainly could be a problem and I would expect at the very least a request/notification to avoid weather. Own nav on an airway or DIRECT to a point is just that with little or no latitude to go wandering off track.
Frankly perhaps it's time they started testing first language english speakers for aviation english if you can read anything else into such a phraseology!!!!

I make a distinction in the clearances that I issue - although whether it is appreciated by the pilots I rather doubt.

If I clear an aircraft to go 'own navigation to XXX' I expect the aircraft to go in a straight line to that point and I will issue instructions to other aircraft on this assumption. In this case I want to know about any wish to make a turn off the shortest track distance to the point in question.

On the other hand, if I just clear the aircraft on own navigation without specifying any particular fix to aim at I'm happy for the aircraft to route in any particular direction.

If it's busy I'm unlikely to use the former option but rather I will instruct the aircraft to route direct to XXX - mainly to avoid the possible misundersatnding that this thread revolves around. In the latter case I will usually offer the clearance in response to a request from the pilot to cut a corner or whatever and I will prefix it with a comment about there being little or no traffic to affect the flight so he/she can route as they wish. I'll only intervene if the aircraft looks like its heading outside CAS, other traffic pitches up that potentially affects the route taken by the first aircraft or the next agency request something different.

Like I say, I doubt that the subtlety is recognised by most pilots but that's the distinction that I make - the upshot is that i'll normally only give 'own nav' when it's quiet and I've got time to keep an eye on where the aircraft go.

Previously, I understood the following to be correct.

Direct.
Direct from present position, to the given waypoint

Own Navigation.
A choice; Direct as above, or returning to the filed flightplan routing without deleting anything.
So if vectors for spacing left you essentially on your original route, give or take a slight offset, you could just renegage in lnav, and back on course.

Or if you chose, hard select the waypoint to accept a slight track change.

But then different instances of this started popping up. ATC cleared Direct to a waypoint. But then after deleting the intermediates, getting sent to them as part of the new routing clearance. So essentially back on the flightplanned routing.

Something that has a fair amount of vagueness about it now.

That works for me too.

I would anticipate some leeway from the direct track (or own navigation track) provided that the aircraft operated to the RNP for the airspace, e.g. the aircraft could be up to 5NM either side of track in RNP5 airspace quite legitimately so I'll figure that in to any separation problem. Modern avionic fits mean this deviance rarely happens though as most aircraft track exactly along the route.

Splitting hairs possibly but to return to track on own nav should involve a 30deg intercept of track unless otherwise approved.

Thanks a lot folks - very informative. (Apols but off line for a few days)

I asked the question because I am not conditioned to interrupt instructions and I find this one rather vague as there are several ways I could use my own nav to a fix (well more that one anyway). Also ,for instance (and just stirring it now), but while I would never deviate from an assigned height/altitude without permission, own nav direct to a fix doesn’t make that clear. If I have latitude to deviate left or right to avoid, why not up or down. Why not remove the ambiguity and just use Direct (or clearly define what own nav means - which you have done above - much obliged).

Should never let idiots like me interrupt an instruction.

Thanks.

Which is exactly why you don't have latitude to deviate left or right to avoid wx. Some of the posts on this thread are absolute garbage. DCT to xxx, means just that. If your method of nav involved some meandering, then that should have been taken into account by the controller. You do not have permission to make wx diversions, whilst on own nav. You must navigate DIRECTLY to xxx. Any "deviation" must purely be nav system inaccuracy. AIP refers (IFR tracking requirements directs you to ICAO annexe 2, which specifies at 3.6.2.1.3).

I had this argume.... I mean, discussion with a colleague recently. As a Tower controller if I issue an early turn off the SID for departure radar I would never use 'own nav dct...'. It seems like a contradiction to me!?!

Surely it is either;

'turn left/right dct xxx'

or

'turn left/right own navigation xxx'.

The latter allows the pilot discretion regarding terrain/obstacle/weather avoidance. If as a controller you would not be happy with the pilot not flying in a straight line to said point you surely shouldn't give the flexibilty of 'own nav'.:confused:

Choclit
It's very simple really, DIRECT XXX is just that. Own Nav is a standard intercept of track to XXX
TP

Direct to means direct to as far as I'm concerned, I want to know about left or right turns. Own navigation is only used if you are under my nav, ie heading.

Eg 1, Pilot "Request direct xxx"
Me "track direct xxx"

Eg 2 Me "for sequencing fly heading 180"
at completion of vector "resume own navigation direct xxx"

If in doubt ASK, an unanticipated turn at the wrong time could be very ugly.

I agree with most of the reasons given, especially those which cite the possibility of (to the ATCO) an unexpected turn. Be aware that there are many locations where one-way routes exist, in reasonably close proximity to each other - probably parallel. You could be at the same level on your route as another flight going t'other way - all separated and radar monitored. But it would all get a bit hairy if you turn to avoid wx, but fail to say anything. So to call first is a good idea IMHO. Thanks.:)

So would you all be happy if I interpreted as follows -

Whilst in Own Nav mode (ie, Autopilot/FMS coupled navigation): "Route Direct To XYZ" means "Here's a shortcut, go direct from present position to XYZ"

After ATC vectors (radar headings): "Own navigation to XYZ" means "No more vectors, resume your own responsibility for navigation directly to XYZ"

Any requirement to deviate from the (more or less) direct routing would imply at least approval of the desired heading - or a return to radar vectoring 'mode'

Yes
No. The reality is that as most aircraft systems can navigate direct to a point you will be cleared direct to the point anyway traffic permitting, however unless the word direct is included I expect you to make a standard intercept (30deg) of track.

Pontius's Copilot....THANKYOU!!!!:ok:
I was reading this thread with my jaw agape at the variation from Air Traffic Controllers as to the meaning of a clearance used hundreds of times every day. I would be similarly shocked if there was a percieved ambiguity in the clearance to climb to a FL :ugh:
Anyway.....I am calm now, after reading your post. Yes thats it. It really IS that simple. Can I buy you a beer? :}


Oh....and RADAR707....if you were a trainee on your first day in the Ops Room and I was your coach and you said you would be getting the coffee for the next several months!!!! How can you say a turn from the expected flightpath is not a problem, and would you tell that to the pilot when he enters an active shooting area or military exersize area? I really hope I misunderstood your post, and you are now going to enlighten me and explain that thats not what you meant at all........:rolleyes:

fourthreethree may be jaw agape because others have the temerity to have a different interpretation of a bit of phraseology/procedure. It may well be used hundreds of times a day but it is poorly defined and can - as is clearly indicated by this thread - be interpreted in different ways.

ferris seems to have come closest to a definitive answer. Annex 2 was not where I would have looked - but the paragraph he references includes the caveat 'Unless otherwise authorized..by the appropriate ATC unit...' which means that if the phrase resume own navigation is interpreted as something else by a pilot then the the Annex 2 words are null and void - for the time being anyway. Unfortunately neither PANS-ATM or the Manual on RTF appear to define what is expected following a clearance to resume own navigation. Interestingly some of the examples of its use do not even require a point to be specified or the words 'direct to'.

Life is a bit easier for controllers. fourthreethree may work at a unit where every single controller uses own nav and direct to clearances in exactly the same way (I've no doubt any that he trained will have ended up agreeing with his/her interpretation just to get out of the kitchen). Certainly there are likely to be generalised views of operating procedures within an ATC unit - there always are. But pilots fly through lots of different ATC environments and will meet - knowingly or otherwise - a variety of expectations when given these clearances. The problem is that almost all of the time the pilot's actions will meet with the controller's expectation - on rare occasions they may not and this is when we find out about differences in interpretation.

For myself, the thread illustrates why I rarely give an own nav clearances - I prefer to give instructions that are less easy to interpret in different ways, maybe 'route direct to' or 'fly heading'.

my last comment
 

Why should we have to search for a definition of DIRECT in ICAO doc's????:confused:
Try the concise oxford dictionary!!!
I know ATC's are genrally lateral thinkers but to be able to read anything else into a clearance that includes DIRECT borders on the ridiculous.:eek:
Has anything changed over the years since I did my IFR rating when I was taught that when intercepting a track (at anytime) involves a 30 degree intercept unless cleared DIRECT to a point???
sheeesh:ugh:

OK, except in the country where I did my initial, "Own Nav" merely meant that the pilot, already in receipt of ATC clearance (hence "resume"- he had to have been on own nav before, and was now on it again), had changed the method of nav (vectors) during which time he had no responsibility for terrain clearance (how could he? he may not have any idea of where he is under/after vectors). The phrase meant that vectors were over, and that the ownus was back on the pilot for terrain clearance. It was defined that way in that country's MATS. The stuff about joining instructions (30 degree track intercepts etc.) referred to a pilot outside CAS receiving an initial ('joining') clearance, or to coming within range of a more accurate nav source (say a VOR) and determining he was off-track (rectification).
There is still the overriding responsibility in AIP to "navigate by the most accurate method"- which these days is going to be GPS or similar, especially in RNP airspace. Personally, I do not think there can be any contradiction between a 'route direct/track direct' instruction, and 'resume own nav', as they refer to different things. If (younger?) pilots, who do not understand the origins of these things (ie that there was a time before GPS- and even radar) can interpret it differently, then there is no point in being correct at an inquiry- which is what Spitoon is saying, I guess.

But I'm with you Tinpusher.