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-   -   Radar vectoring advice please (https://www.pprune.org/atc-issues/547423-radar-vectoring-advice-please.html)

Propellerhead 11th Sep 2014 21:31

Radar vectoring advice please
Hi all,

I'm a new simulator instructor (pilot) and part of the job involves simulating ATC and giving accurate radar vectors to a final approach (normally to an ILS). Could anyone help me in giving some practical 'rules of thumb' please? Specifically how far to go downwind to achieve a particular length final (10nm for instance) and then at what point to turn them from base leg to final and what range of intercept headings to use? Also any rules of thumb for adjusting for head/tail wind on base etc. Having done it a few times with varying success / finesse it seems quite an art form!

Many thanks!

Tarq57 11th Sep 2014 23:07

My job is aerodrome control, but I've been a radar controller in a former life (area) and done a few ATC sim sessions which mainly included approach, but am by no means experienced/competent in this, so take this for what it's worth.

The standard ILS intercept heading (or track) is 30 degrees from the localizer.
If there is a strong crosswind (=tail or headwind on base) this may be varied slightly to facilitate an easier 'turn on'. More importantly, particularly with a strong tailwind on base, or with any aircraft showing a high groundspeed, the lead-in distance for the turn needs to be increased. Normally this distance is about a mile. Maybe a tad more.

Expect an aircraft downwind being vectored for base to cover 1-2 miles further downwind, depending on the groundspeed, during the base leg turn.

Those are very general rules of thumb, each controller will vary them on the day, depending on the wind, and the speed of the aircraft being vectored.

That all said, the modern trend is moving away from vectoring on to a LLZ, and more toward pilot-interpreted approach procedures, such as STARS.

Not too far into the future, it's likely that in the majority of places, there won't be a lot of actual vectoring going on any more. At least for intercepting approaches.

throw a dyce 12th Sep 2014 08:40

Hi Propellerhead,
In still air and a rough guide vector downwind on the reciprocal of the Final Approach track,no closer than about 6 miles from the final approach track to about 11 miles downwind.Base leg turn 90 deg,and when the target has about 1.5-2mile to final approach track turn onto closing heading no more than 40 deg from final approach.That should get a 10 ish mile final.You also want about 2 mile of level flight before intercepting the glide path unless using a continuous descent approach.
If you are correcting for the wind then it's just experimenting and adjusting the headings,to correct the drift from wherever the wind is blowing.Strong headwind,base leg turn earlier.Tailwind give it more room.Crosswind change the closing headings to avoid going through the localiser.
We were always taught to vector wide and then you can tighten them up.Not the other way round.
Your right though it is an art form,especially get minimum spacing in a sequence.

chevvron 13th Sep 2014 22:48

Downwind distance depends on the pattern altitude for the procedure, bearing in mind ICAO recommends about 2nm of level flight to stabilise on the localiser before glidepath intercept, hence if you're using the equivalent of 1,500 ft above aerodrome elevation, GP intercept will be 5nm on a 3 deg GP, so the aircraft will need to be aimed for localiser intercept at not less than 7 nm.

kcockayne 14th Sep 2014 08:05

throw a dyce

& , you can add, the most fun part of the job !

HEATHROW DIRECTOR 14th Sep 2014 08:57

This thread could be along the lines "can someone tell me how to ride a bike?" Practical experience is what is required in lieu of reams of paper.

Propellerhead.. If you haven't already done so it would be worth sitting in with some radar controllers to see how it's done. GL

airac 14th Sep 2014 18:19

If this were FB I would like the last post from LL director :)

Propellerhead 19th Sep 2014 14:32

Thanks guys, really useful advice. I'm sure I'll get practiced at it but useful to have some rules of thumb initially. At least I control the environment in the simulator which gives me a big advantage! And I'm only vectoring one aircraft who's instruments I'm looking at as well as the 'radar' map.

I presume when people talk about vectoring to 11 miles downwind that's a straight line drawn at right angles from 11 miles on the extended centreline? The aircraft's DME will be reading an 11 mile arc so will need to read more than 11 miles before turning in. I'm sure I can work it out using some GCSE level maths! Update : I reckon abeam the 11 mile point, with a 6 mile base leg the DME reads 12.5 using Pythagoras!

NorthSouth 19th Sep 2014 17:28

Not a controller, but I'd just throw in the thought that if you vectored traffic downwind 6nm out from the FAT, at most UK airfields in controlled airspace that would put your traffic right on the boundary of, or even outside CAS, which is not done for fairly obvious reasons.

Downwind leg 4nm out from the FAT is more like it.

HEATHROW DIRECTOR 19th Sep 2014 17:56

If the downwind leg is only 4nm away from the final approach you would not stand a chance of turning the aircraft onto the ILS without it going through especially if the wind was playing up. Also, make sure you get the speed back around 180kts for the turn on.

kcockayne 19th Sep 2014 18:00


Pythagoras never used to feature in my vectoring calculations; nor any other kind of maths. Just experience & "play it by ear".
There are so many variables to factor into any kind of mathematical calculation that you would not know which one to use & when !
Certainly, when we were really busy, you just didn't have time to make those sort of calculations. Every situation was different. All that was needed was experience & expertise.
The human brain is a wonderful thing (far better than computers). Using it in ATC doesn't require complicated assessments & calculations (unlike computers).

Loki 19th Sep 2014 18:22

Agreed....I used to consider things a bit more doing area work, but approach involved a much more intuitive way of doing things.....at some level I must have been calculating, but not consciously for much of the time.

HEATHROW DIRECTOR 19th Sep 2014 19:56

<<The human brain is a wonderful thing (far better than computers). Using it in ATC doesn't require complicated assessments & calculations (unlike computers).>>

Agree 100% and I wish that the geniuses who come up with CAAS, FAST, Tunnels in the sky and whatever the current "magic answer to ATC" is called would understand that.

Talkdownman 19th Sep 2014 21:01

Remember PACTAS?

GAPSTER 21st Sep 2014 07:59

Disregard all above...

....stand by for Point Merge ��

NorthSouth 23rd Sep 2014 11:06


If the downwind leg is only 4nm away from the final approach you would not stand a chance of turning the aircraft onto the ILS without it going through especially if the wind was playing up
Well, they do it every day of the week at Newcastle, Durham, Norwich and others where the configuration of CAS means that you're either in the CTR or in Class G.

bekolblockage 24th Sep 2014 11:13

While you can't beat years of sitting in front of the screen like HD, here's a reasonable rule of thumb that I was taught for turning from base to intercept the LOC;
Start giving the ATC instruction to turn to the intercept heading about 1NM for every 100kts ground speed from the LOC. eg 250kts- 2.5NM, 200kts-2NM
By the time you finish the "turn right heading... cleared ILS...and the pilot reacts, the interception should just about a continuous turn.

As for adjusting the intercept heading in wind, as Throw a dyce mentioned, if you are trying to intercept at a track of 40 degrees from the LOC, you need to adjust the intercept heading to account for the drift angle expected on final. At normal jet speeds thats about 10 degrees for every 30 kts crosswind.

So if you have a 30 kt tailwind on base, you should increase the intercept turn by about 10 degrees; if you have a 30 kt headwind on base then you need to back off the turn about 10 degrees. e.g. in still air a turn from right base to intercept Runway 09 at 40 degrees would be to heading 050. With a right crosswind on final ie tailwind on base, the intercept heading would be 060. With a left crosswind it would be 040.

See how that goes.

Buster the Bear 24th Sep 2014 22:16

Look for the thread relating to Swanwick TRUCE. Get yourself booked onto an airports recurrent afternoon at Whiteley. You will not regret it.

Email [email protected] for more info

Propellerhead 26th Sep 2014 16:29

Thanks guys, some really useful advice. It's worked very well this week. I wasn't planning on using Pythagoras whilst vectoring(!) However my calculations seem to work that you need to add 1.5 miles onto the dme if you're 6 miles base. Turning base at 12.5 dme brought the aircraft perfectly onto the LOC 2miles before top of descent at 10miles. I presume radar controllers have range grids on the screen? I've only got a spiders web from the airfield and a 12mile extended centreline plus I can see the aircraft's navigation display and DME. Out of interest how do you guys calculate track miles to run? Do you just add 10 + 6 + 5 for final / base / downwind or do you have a more advanced way?

throw a dyce 26th Sep 2014 17:07

On radar displays we use range rings from the radar head,usually 5 or 10 miles.
Track miles.It depends where they are in the radar circuit.
Downwind: I would range and bearing from the point I intend turning base.(10+6+ whatever the distance to that point)
Closer in: Measure from the 10 mile final point.
Most radar now have the RBL function,but being old school I can do just as good a job with the mark one pen and thumb.:ok:

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