Quadrantal Rule??

[FlightDeckDave]

Maybe i'm being dense, however perhaps someone could explain the quadrantal rule to me. As i understand it, when flying above 3000ft depending on the direction u are heading u take one of 4 combinations of flight level.

But when i look at the diagram is it possible for 2 planes to be flying out of controlled air space and pass over each other with a separation of only 500ft when the minimum should be a 1000ft?? Perhaps i am confused and dont understand the diagram

Thanks in advance

[10 DME ARC]

Why do you say 1000ft min separation? Its designed to aid collision avoidance out side CAS giving 500ft separation. Only expect 1000ft separation between a/c both receiving a RAS out side CAS!
:)

[Spitoon]

OK Dave, you've picked a tricky question for an early post. The answer is not straightforward and how it is best explained depends on how much you already know. Your profile doesn't give much away!

I'll try and give a bit more explanation than 10D and it will either make a bit of sense or you'll feel like grandmother learning how to suck eggs. Aircraft fly around in different classes of airspace and according to different sets of rules. The air traffic service you get (if any) depends largely on the class of airspace. How much you are separated from other aircraft depends on the type of air traffic service you're getting and the rules you are following.

Aircraft that are flying under Instrument Flight Rules - IFR - in most classes of controlled airspace will be separated by a controller from other aircraft also flying IFR. Aircraft flying under Visual Flight Rules - VFR - are more usually responsible for flying by lookinng out of the window and avoiding collisions by seeing and avoiding other aircraft. Note that ATC separation is much 'bigger' than collision avoidance.

The Quadrantal Level system, which is pretty much unique to the UK, is intended to help with collision avoidance for flights outside controlled airspace and not getting any form of air traffic control service from a controller. And, yes, it is a rather basic way of getting at least 500ft vertical space between two aircraft whose paths may cross.

I hope this is not too Noddy and helps.

[FlightDeckDave]

Yeah thanks guys for the above posts, it does confirm what i thought that planes can fly at 90degrees at each other with a vertical seperation of 500ft, it was just confusing as i thought planes always had to have a minimum of 1000ft vert. seperation but i guess not. But then again 500ft is definately better than 0ft!

[PPRuNe Radar]

Aircraft that are flying under Instrument Flight Rules - IFR - in most classes of controlled airspace will be separated by a controller from other aircraft also flying IFR.

That has certainly confused me. In what class of Controlled Airspace will IFR flights not be separated by a controller ???

[Honey Monster]

But when i look at the diagram is it possible for 2 planes to be flying out of controlled air space and pass over each other with a separation of only 500ft
FlightDeckDave
If you think further about the Quadrantal Rule, you will realise that it is possible for two aircraft on tracks which cross at 89 degrees to have no vertical separation. e.g. one aircraft heading 360 and one crossing its track left to right heading 089.
The Quadrantal Rule cannot negate the risk of collision, it can only reduce the risk.
Reg

[Spitoon]

PPRuNe Radar, think about class F and an IFR flight under a service from a controller and a non-participating IFR flight in the same airspace.

[Take up the Hold]

Spitoon

Class F is not controlled airspace. It is advisory airspace.

TUTH

[Spitoon]

Yeah, OK. You win. It's late!

[Giles Wembley-Hogg]

PPRuNe Radar

How about VMC climb and descent in Class A or B? No separation provided by the controller there. Not a permitted technique in the UK, I might add.

G W-H

[Lock n' Load]

Just to tie things up for FlightDeckDave...
Separation as provided by ATC to IFR aircraft in contolled airspace, and to IFR aircraft recieving a radar advisory service outside controlled airspace, is not always needed. Aircraft can fly in formation, for example, with the agreement of both (or more) pilots. Even when in controlled airspace there are circumstances when IFR aircraft do not need standard separation, for example when an aerodrome (tower) controller uses "reduced separation in the vicinity of the aerodrome" or when an aircraft is on a visual approach following traffic which the pilot has in sight.
Outside controlled airspace, VFR aircraft and IFR aircraft not receiving an ATC service simply have to miss each other.

[anotherthing]

Flight Deck Dave.

The quadrantal rule is an aid.

The pilot is still responsible for collision avoidance under the 'see and be seen' principle.

There are a lot of other factors to take into account - pipeline/wire (tho not usually taking place above 3000'!!) inspection flights, military flights etc.

a good lookout is the number one form of separation in uncontrolled airspace if flying VFR

[Bern Oulli]

VMC Climb & Descent. MATS Pt 1 Section 1, Chapter 3 para 5.5 refers.
To avoid excessive delays to traffic when radar is not available (my italics), controllers may authorise an aircraft to climb or descend in VMC provided:
6 provisos which can be found here. (http://www.caa.co.uk/docs/33/CAP493PART1.PDF) However, the important bits are - essential traffic given, the pilot agrees to provide own separation, in daylight hours, in VMC, in Class D,E,F and G airspace below FL 100.
Having said that I recall a day at Preston Centre (that dates me) when the controller on a busy Pole Hill Sector (no radar) said words to the effect of "Can you see the 707 contrailling ahead of you?" Answer in the affirmative. "Roger, formate line astern and climb through". Ah, those were the days. This all said, by the way, with a pipe firmly clamped between the teeth.

Sorry, drifted off the thread.

[spekesoftly]

Interesting to see that MATS Pt 1 Section 1 Chapter 2 Page 3 NOTE 1 specifies the VMC minima for VMC climbs and descents in Class A airspace ! :confused:

Perhaps one part of CAP 493 has not been amended to accord with another?

[2 sheds]

For the record, the Quadrantal Rule refers to Magnetic TRACKS, not aircraft headings!

[Highland Director]

Interesting to see that MATS Pt 1 Section 1 Chapter 2 Page 3 NOTE 1 specifies the VMC minima for VMC climbs and descents in Class A airspace !
I wondered when someone would raise that one! Another MATS pt1 anomaly if you ask me. On my last ULE, I asked the SRG representative why the UK MATS includes criteria for a practice that it does not allow.
Answer: 'I'm not sure about that one actually, I'll get back to you'
He never did!

[Bern Oulli]

I knew that (once)! :uhoh: I just didn't want to er cloud the issue, so to speak.

[rowdyyates]

Dave, when flying outside controlled airspace and not in receipt of an air traffic control service ie not receiving RAS/RIS/procedural APC, there is no such thing as `minimum seperation`. The idea of the quadrantal rule is that (in theory) it will provide a minimum of 500ft vertical seperation between aircraft on converging tracks, and a minimum of1000ft between aircraft opposite direction. Hope that makes sense!
Regds,
Rowdy.
Maybe i'm being dense, however perhaps someone could explain the quadrantal rule to me. As i understand it, when flying above 3000ft depending on the direction u are heading u take one of 4 combinations of flight level.

But when i look at the diagram is it possible for 2 planes to be flying out of controlled air space and pass over each other with a separation of only 500ft when the minimum should be a 1000ft?? Perhaps i am confused and dont understand the diagram

Thanks in advance

[chiglet]

And nobody has mentioned that it all has to happen on the Standard Pressure Setting of 1013 :ok:
watp,iktch

[chevvron]

From a study done many years ago, at the time only the UK and Mauritious used the quadrantal rule, everywhere else using the semicircular rule.

[2 sheds]

Re 1013, actually FDD mentioned it in original post - "...flight level...".