Radar Headings vs. Flight Planned Route
 

Can someone help me understand the behind the scenes processes that make Radar Headings so popular with London.

On a recent flight from EHRD (FL100) the various Continental Controllers all had me flying either the filed route or DCT. However, the moment I arrived in London I was on headings (which exactly matched my filed route).

Similarly a flight to Scotland and back, on the way up I was on headings issued every 40 miles or so that tracked about 3 miles East of my planned route (until TNT). Coming back down, I was cleared own nav via several waypoints, but the handover to London once again went, 'Say Heading ... Make that a Radar Heading' and once again tracked exactly over my planned route but on Radar Headings.


Given the radar headings and the dct links between the waypoints followed the same path over the ground, there must be some procedural advantage for London of having everyone on headings (but the same advantage doesn't seem to apply to Amsterdam).

On headings minimum lateral separation can be used, on own nav it can't be.

So you're on headings so that other traffic, also on headings, can be climbed/descended through your level at no less than 3nm lateral separation.

If you're at FL100 there will be a lot of other traffic in the TMA that needs to be climbed above you or descended below you.

Roffa
 

Is that a "local" rule or procedure or an ICAO standard? I'll be using ICAO regs. for the first time in my career very soon. In the US we can use 3 miles regardless of whether the aircraft is on a heading, on route, or "direct."

V361
 

I guess your system works else the FAA wouldn't approve it , but if you're using 3 miles separation & one guy, not on an assigned heading, deviates just slightly, say to avoid a bit of wx, have you not got a "deal" ? Or is the assumption that no one will deviate without asking first ?

What surprised me a little, and prompted the question, is that with one exception (traffic crossing 1000 ft below) there was no one visually or on the traffic system showing within 6-8 miles anywhere close to my altitude for the whole time I was on headings. (I don't have full TCAS, but generally would expect to detect large aircraft transponders quite well.) It was from this that I guessed there must be some procedural rule or mental advantage London Controllers have when putting someone on headings. It doesn't seem to happen anywhere else and certainly my US, Dutch and German experience is that getting a heading means you are consciously being vectored off ones flight path rather than just ensuring you remain on the flight path.

It's certainly not ICAO. We use it "out of common sense" when tfc will come pretty close, high speed & nearly opposite. But all the time ? Sounds like overkill...

Due to the congestion and complexity of the route structure in the London TMA, tactical positioning of traffic with the use of headings is absolutely essential for an expeditious traffic flow. If all aircraft were routinely left on their own navigation the TMA would grind to a halt.

You may not require a heading to be separated from conflicting traffic in the immediate vicinity, but tactical positioning early on can prevent numerous conflictions from happening 20, 30 or even 50 miles ahead.

If you were overflying the TMA at FL100, you can be assured that if left on your own navigation, the result would be a significant reduction in the expedition of pretty much all the other traffic.

Lots of aircraft; complex airspace/sector design; separation standards; presentation to next sector, etc.

Why don't you arrange a visit to Swanwick and have a look for yourself; you'll get the picture fairly quickly I would imagine...

Thank you for the suggestion. I will do so.

I can understand the logic for tactical positioning of traffic. I also routinely experience in any busy TMA (with no complaints or surprise - because I know that's what's needed to keep things flowing).

What surprised me was being 'tactically positioned' exactly on my flight planned route (which out of interest on the South Coast was KONAN DCT LYD R803 SFD (The headings kept me within about 1 NM of my original magenta line) and going North was tactically vectored about 2 miles east of DTY DCT SAPCO N57 (to about TIPIL where it was own nav POL)

More reasons then from the route you gave first:

KOK-KONAN-DVR is opposite direction to all the London TMA traffic departing via DVR so giving you a heading nudging you slightly south of track gives us the best amount of space to get the TMA traffic quickly through your level. The LCY traffic will be passing FL100 somewhere between DET and DVR as is the Stanstead & Luton departures. Next you cross N613 between SOVAT & SANDY, all LCY, Biggin Hill, Southend and Rochester traffic have to be FL80 by SANDY, if you are on your track in conflict with one of these arrivals, we cannot achieve FL80 by SANDY unless you are vectored slightly southwards. The next track you conflict with is again traffic into LCY etc inbound along G27 (HASTY-BEXIL-ROKOS-SANDY that have to be FL100 by HASTY. Being your level, you will be vectored off track to avoid this route. Next, as you approach SFD (or 10nm before it) you will have a steady stream of LGW arrivals crossing from right to left attempting FL70/80 around TIMBA, again, if you are on track, that is not achievable. Once you cross that track, then depending on the LGW runway direction, you could be in direct conflict with departures if they are on easterlies. If on westerlies, then you will be in conflict head on with LGW arrivals via GWC-HOLLY-WILLO which also need to descend through your level.

For all those conflictions, you need to be on a heading to ensure separation or to tactically position you so other aircraft can achieve agreed levels. As to why it, in your opinion, only happens in the London TMA, then I guess that we are just that busy that you have to be.

Excellent detailed explanation there 5mb, PPRuNe at its best! :ok:

And one would be more surprised by vectoring that would have taken you much further from your route - as this would have required lots of coordination, killing the entire idea. You get 2nm off, someone else 2nm off on the other side, et voila.

Agree with Spekesoftly. I bet Mr Flynn knew nothing about all that!

Thank you all for your replies. Some of which I knew, some of which I didn't. Probably most interestingly, I hadn't appreciated that London requires one to be on headings to achieve reduced separation.


Equally, I had expected by the time I was 4 miles off track of L9 on my way to LYD I was clear of everyone climbing out DVR KOK (equally, I had thought most of the traffic was FL150+ by the time they reach DVR).

Live and learn! And I will take up the various offers of a visit.


Thanks.

ETC
 

In a case where the pilot deviates without asking, should it result in less than standard separation, it would be a "pilot deviation," and not a controller error/airprox here in the US. It is certainly not unusual to put aircraft on headings when in close proximity. BTW does ICAO have a "degree divergence" rule where you can use less than 3 miles if aircraft are assigned diverging headings by ??? degrees? If so that may explain why London TMA puts so many aircraft on headings. It's only allowed in terminals in the US last I knew, but center/area has been trying to get it in areas where 3 miles separation is available.

V361
 

Thanks for the reply. Sorry, can't help with the ICAO query - I do Apc Rad in the UK. We can use 3nm separation but with quite a few restrictions e.g. both aircraft identified, intentions known, within certain range of radar head, & separation must be back to 5nm or more before transfer to the Centre. I suspect this it the same at most units.

Vector 361 - there's no such thing in the UK, can't speak for ICAO

In the London TMA 3 miles separation is subject to a host of other conditions - below FL245, a minimum distance from the radar head (depends on the radar source) , identified and talking to a co-located controller with a rapid means of co-ordination.

However approach controllers can use 2.5 nm on base leg and final within 20nm of touchdown and I understand that is ICAO too.

From your post it seems that it's common in the US to allow aircraft to be on their Own Nav 3nm from each other? Maybe we're overly cautious but it wouldn't happen here - at least one and usually both would be on headings if that close.

Here in Austria its completely up to the controller how to use the 3nm sep; outcome has to be 3nm or 1000ft, no matter how.

That doesn't mean everyone here is pushing his/hers adrenaline by letting 3.1nm happen with a/c almost opposite or sharply crossing, but it surely is handy at almost parallel SIDs which are still close to each other (must be bloody inconvenient to assign headings to a/c on parallel tracks, one overtaking the other with min sep of 4,5nm when staying on the sid).

What's the real advantage of headings vs planned route? Don't mistake me, I love headings and use them whenever things take a closer look.
One argument I heard often is wx-deviations. Well, I sure count on any a/c to report any deviation, as is required (flight planned route doesn't allow for any deviation without reporting, at least in my FIR; same with heading)
Below the line I should feel even better when letting 3.1nm happen on flight planned route, because that is what is tracked. A heading's track might change when descending/climbing because of different wind.

I think ICAO says 10 nm from touchdown.

I have to say i was allways puzzled about the use of radar headings within the UK. Our flights from stansted to glasgow, manchester or even belfast were quite often completely on radar vectors from shortly after take off until the ILS whereas domestic flights within germany or spain are usually done using directs or flight planned route until within the TMA of the destination where radar vectors are used for positioning onto the approach.

That said i allways felt safe that way as the ATCOs are obviously knew what they were doing, it just was a source of conversation on the flightdeck as it is unusual when compared with the rest of europe.