Radar Headings And Not Sid

[AI101]

Hi

Can any ATCO here clarify why when departing stn (almost all SE airports) we get given radar headings which follow the sid exactly instead of leaving us to fly the sids and reduce contoller workload, as is the case in most other countries.

AI101

[Defruiter]

For separation. If you are on your own nav on the sid, there is a chance you could wander off, as it's your own navigation. When we lock you on a radar heading, that proves separation against something else. 2 aircraft close on radar headings (should) never hit. 2 aircraft close on their own nav could equal a big problem ;)

[coracle]

AI101

When flying in and out of Stansted, you are flying in very crowded airspace and has been already mentioned you need to be on a heading so that we can prove our separation.

For example, if on a CPT SID then the Stansted FIN controller has to climb you to FL 70 or 80 (depending on the atmospheric pressure), through downwind traffic for Stansted (if using RWY 05) and also through traffic which they are working inbound to LUTON which needs to be positioned "through the gate" at 5000 feet before transferring it to NW DEPS. This is also true of the BUZAD departure, but also as BUZAD is quite a long way to the WEST the next sector (NW DEPS) doesn't really want you flying to BUZAD as you get in the way of nearly everything, and so you normally get transferred on a heading of around 295 - 305 degrees. This is known as pointing you towards the corner.

If departing on a CLN SID then you get mixed up with LL BPK departures, LC CLN's, GW CLN's, WU CLN's as well as over-flights, and the NE DEPS controller will put you on a heading to parallel you off with other traffic so you can be climbed to the agreed level.

The only SID you might be left to fly at least until DET is the DVR SID, but this is not always the case as there might be a GW or WU DVR departure which you need to be separated against.

The fact of the matter is that the South East has some of the busiest airspace certainly in Europe, if not the world and headings are used to keep you apart and so you can be climbed and descended and also so we can prove our separation.

This would be far more easily explained if you were able to come down to Swanwick for a visit where I'm sure you would be made most welcome.

[radar head]

When a controller locks you onto a heading instead of a SID, they may want you to continue on that track until they decide you should turn. The SID track may turn you at a point which would put you into conflict with other traffic or make the controllers task of providing separation more difficult. Admittedly, some controllers do this out of habit and need to be reappraised of the benefits of letting the pilot be responsible for the navigation.

[Bullethead]

I've often wondered the same thing.

So in places like that, which are congested, why have SIDs and the associated clearance and readback hoo haa? Why not make all departures radar departures? :confused:

Regards.
BH.

[coracle]

The SID is a shortened form of a clearence. They do perform a function and enable airfields to have freeflow departures for some and sometimes all of their SIDS. If we had radar departures then each individual aircraft would have to be co-ordinated making the tower and radar controllers task impossible due to the amount of telephone calls they would have to make.

Also could you imagine the r/t congestion at the airfields? Instead of "EZY 6AM, cleared to Amsterdam CLN 5R departure, squwak 6361" it might be something along the lines of "EZY 6361 after departure climb to 3000 feet, turn left heading 105, when established on the heading climb to 5000 feet etc etc". This after the phone call to the radar to get headings and altitudes.

SIDS although perhaps not perfect do eliminate a huge amount of workload for crews and controllers alike.

[Gonzo]

SIDS also allow for precise track keeping at low altitudes to conform with Noise Preferential Routes. Once above 4000, out of Heathrow at least, you can be taken off the SID with a heading.

[AlanM]

SIDs also give you radio failure procedures.

[airac]

"SID " also used to sell shares in British Gas:ok:

[Mister Geezer]

What AI101 and others are scratching their heads over is that the aircraft they fly will probably fly the SID track very very well and for many aircraft nowadays, the days of wandering to a beacon are long gone. However whilst avionics and nav accuracy have made significant progress, the practice of ATC using headings have been around for donkeys. Locking an aircraft on a heading has and still is a fundamental method of separating aircraft but it dates to a time when the majority of aircraft did fly from VOR to VOR and did at times wander slightly off their track but still be within the tolerances for tracking etc.

[Gonzo]

What AI101 and others are scratching their heads over is that the aircraft they fly will probably fly the SID track very very well and for many aircraft nowadays, the days of wandering to a beacon are long gone.

I would beg to differ. I see a vast difference in tracks from day to day, at least initially within the first five miles of the SID.

[TrenShadow]

A lot of the SIDS that I'm familiar aren't just a simple track point A to point B to point C etc, but say track XX degrees until through 5400', then turn to track towards point B, passing through 6700' now turn to track YY degrees until 8400' then track direct to point D. etc.

This means a/c will fly a different route depending on their climb profile.

Headings give ATC control over the exact turning points based on the traffic disposition at the time.

[JustaFew]

Agree on that one, Gonzo. Sometimes see runway heading flown, instead of straight ahead (the plane can be blown off course due to a strong cross-wind). But that's another thread...

[Mister Geezer]

I would beg to differ. I see a vast difference in tracks from day to day, at least initially within the first five miles of the SID.

I was referring to when the aircraft is a bit further on than just a few miles after departure. Anyway as previously mentioned ATC can't do anything in the first few miles due to noise. Once the majority of aircraft are high enough to be vectored then the tracking should have settled down and thereafter it should be to a pretty good standard with most modern aircraft.

[GunkyTom]

Anyway as previously mentioned ATC can't do anything in the first few miles due to noise


That isn't necessarily true. Our noise routeing restriction is 3dme or 1800', whichever is sooner,however there are exceptions for certain types and routes, therefore a heading after departure is the only surefire way to have the a/c flying a track that you want.

[MrApproach]

In Australia the SIDs form part of the community noise consultation programme and therefore controllers are not allowed to cancel them without good reason. The major reason is normally weather, when we switch to radar headings. Conflicting traffic is not supposed to be allowed on SID tracks. (Yeah, I know we have a lot more room that the Poms!) The headings are limited by terrain requirements. (That is because you are vectoring below the lowest safe so it can only be done in surveyed areas. An exception is by day in VMC when an IFR pilot can provide his/her own terrain separation.)

There is no doubt however that if separation is to be guaranteed the aircraft involved need to be on headings even if the headings are the same as the SID. If your separation out of Southend is so critical I would recommend constructing a radar SID which pins the departures to a heading instead of track, there is no reason I know of why freeflow or auto release departures cannot apply to a radar SID.