360 turn or vectors

[jaker]

Hi all,

anyone ever make approaching IFR commercial flights do 360 turns for spacing or do you always just vector them for a longer final/give additional headings in downwind etc? I know its a bit of an issue of poor planning if you haven't got a proper sequence arranged well in advance anyway, and of course one orbiting flight ahead may become a problem if theres many following behind, but just out of curiosity, would you as an ATCO feel uncomfortable making commercial IFR flights do orbits instead of extra vectors?

[ZOOKER]

No, providing the crew was appraised of the reason for it. Been on the flight-deck when this has happened too.
Sadly, sometimes, sh*t happens.

[HEATHROW DIRECTOR]

There can be many reasons why delaying action may be necessary and who said anything about "poor planning". What if the tower rings up and says the runway will be out for 5 mins while debris is cleared? How about an ambulance or police helicopter on a high category flight? Drop in RVR requring an increase in spacing, etc, etc.

An orbit contains the aircraft within a certain area. Leaving it running downwind can introduce problems, running outside of CAS may be one. I must have done it a thousand times and it's no big deal.

[Talkdownman]

An 'orbit' is a standard tool in a radar director's toolbox. At 220kts (Jetliner average min clean) a 360 equates to 10 track miles. A Hold normally equates to 18 track miles. And that's just two 'tools' for modifying track distance to facilitate sequencing and CDAs. There are various methods of 'path-stretching' for effective and efficient sequencing eg. turning the long way.

'Poor planning' indeed...what an insult to radar directors...

[aluminium persuader]

Amongst our weaponry are such diverse elements as....:E

[ferris]

I think I mentioned poor planning once, but I think I got away with it....

[jaker]

Thanks for replies. Reason I asked was because I've made IFR commercials do 360s occasionally in "normal" traffic (emergencies etc aside) and gotten a strange look from colleagues, with comments like "shouldnt do that" so wanted to hear other opinions on the issue.

[mebur_verce]

Did your colleagues mention why you shouldn't have done that?

[5milesbaby]

Used orbits or the "long way around" turns several times in enroute for various reasons including to lose height to make level restrictions or just increase spacing. Normally this can be achieved with a few vectors and appropriate speed control but when you get a bunch transferred late all merged into one with a tailwind then not always possible. Now I wonder who would do such a thing.........? :}

[On the beach]

Sequencing 101

Standard holding pattern = 6 minutes
360 orbit = 4 minutes
Dogleg 60 right for 1,2,3 minutes, then 120 left for 1,2,3 minutes then 60 right back on-track = 1,2,3 minutes delay.

Good planning not poor planning.

End of lesson

P.S. Now I wonder who would do such a thing.........?

Probably 10milesbaby :E

[late-joiner]

Is it different for large aircraft? I have just done my IMC training in a PA28 and an orbit at rate 1 would take 2 minutes and the standard hold pattern would take 4 minutes.

[wiggy]

Is it different for large aircraft?

Sort of.

One problem is that the "heavies" typically hold clean at perhaps 210 - 230 knots IAS or even more, dependant on type. If you use the rule of thumb that the AOB required for a rate one turn = ((TAS/10)+7) you'll see that at normal holding altitudes in the Terminal Area of say 7 - 12000 feet, you need at least 30 degrees of bank to generate a rate one turn. Trouble is most authorities stipulate a 30 degree AOB limit, so with the bank limited the rate of turn reduces below rate one.

In addition the Flight Management Computer, which feeds the Flight Director/Autopilot, will attempt to achieve a fixed in-bound leg time, rather than a overall four minute timing; as a result it's certainly not unusual so see 4 1/2 to 5 minute holds.

[5milesbaby]

I can wish On The Beach, 10 miles means I don't need to do anything!! 0milesbaby far more appropriate!

[Duane]

I think an orbit is that absolute last option for sequencing in my opinion, Id use it in a pinch for sequencing when i have no airspace left to vector.

I have used it, the airspace I control is rather oddly shaped on final and if a training aircraft does something unusual, other than holding on the localiser, the only way to fix it is an orbit.

So yeah, not worlds best practice, but better than a sep breakdown.

[jaker]

Did your colleagues mention why you shouldn't have done that?

Well, I didn't get a definitive answer. Nobody says you can't do it, but guess it's become bit of a standard practice not to do it for commercials.