Intersection Departures

[mad_jock]

What is the def of a Intersection departure?

I am a low houred FO and am still on the steep bit of the learning curve with all the stuff which i wish the ATPL exams had actually taught us.

The reason why I ask this is because this morning we had I think a 757 roll off 24L from Tango at man and a A320 from the next hold up about 100ft further on. After 2 mins the A320 was cleared but refused it and wanted 3 mins. We went from behind them with 2 mins. I asked the LHS who said he would have rolled with 2 mins and after getting home have now checked my notes and nothing found.

I can see there is no question if there is 100's ft between the entry points but with tight holding points on or before threshold where the difference could easly be covered by the difference between a rolling TO and a brakes off TO?.

The only other thing I can think off is that the 757 is such a dirty bugga for vortex the A320 crew used it it as a good exuse to get a bit more seperation (which seems quite a sensible idea to me)

MJ

[PPRuNe Radar]

Mad Jock,

Have a look at this. Might answer a lot of your questions I think.


Wake Vortex AIC (http://www.ais.org.uk/aes/pubs/aip/pdf/aic/4P188.PDF)

[expedite_climb]

Wake vortex separation is 2 minutes with a lighter a/c following a heavier a/c UNLESS - the heavy went from the full length and the lighter is going from an intersection - in which it is 3 minutes.

Basic air law question from PPL level.

[mad_jock]

cheers PPruNe Radar.

I had a look at that one with my notes.

I don't have a problem with say Hotel on 24R it is definatly a intermediate point on the runway so it would be 3 mins. It fits fig 14

Its the holding points which are all grouped with fairly close spacing round the departure end.

Its just something I would like to see whats expected from me. I could imagine if the controllers who are keeping everything tight try and slip in 2 out bounds in a space, when you line up and are cleared you announce you need 3 mins instead of 2. It will cause all sorts of mayhem.

Gut feel as a pilot is use common sense and as they are so close and go for it (unless airmanship dictates otherwise heavy or 757 in still air) but I was trying to suss out from a ATC point of view if these threshold holding points are counted as intermediate points or are just all lumped into one departure point.

It means that as a FO i will ask the Captain before we get near the holding point so I can inform ATC if he/she wishes a 3min seperation from the one in front, if the controller looks as if they will try and do the nice thing and sqeeze us in.

MJ

[PPRuNe Radar]

I'm sure a Manchester lad or lass can elaborate further .... unless they've all gone to Canada by now !!!

[brimstone]

I'm not a Manchester controller but the AIP says that for the purposes of vortex wake separation the following links are considered to be the same departure point.

24L - Links Tango, Victor Alpha and Victor Bravo or
Links Victor Alpha, Victor Bravo and Uniform or
Links Victor Bravo and Uniform

:confused:

[mad_jock]

Thanks Brimstone thats just the ticket.

MJ

[caniplaywithmadness]

Could also be because he was following a 757 and the unique characteristics of the vortex from a 757 (which whilst a medium, behaves like a heavy) he wanted 3 mins, many pilots do, and usually forget to tell ATC which is a bit of a ball ache on single rwy ops with a tight gap!!!.

[52 North]

If the departure vortex of a 757 is particularly bad for a following aircraft, why has it not been categorised as a Heavy for departures?

Some pilots of medium cat a/c at LHR have accepted an 'aircraft ahead, wheels off ground' take off clearance behind a 757 yet this pilot would not even accept 2 minutes (which I know he is perfectly entitled to do, it just makes ATC's planning a bit more difficult).

An intersection departure of a medium behind a 757 categorised as a heavy would require 3 minutes so at least ATC could plan for that. I wonder what effect it would have on LHR's dep rates?

[caniplaywithmadness]

It's not categorised as a heavy because it doesn't fall into the mtwa of the heavy group, it falls into the medium group.

On final approach, an extra mile is added for medium a/c following a 757, purely because of the unusual vortex characteristics of this aircraft.

In this particular case at Manchester, even if the lead a/c was a heavy, the controller can still use 2 mins vortex because the holding points are deemed not to be separated and the intersection departure requirement does not apply in this scenario.

[360BakTrak]

If I remember correctly isnt a 757 classed as an 'upper medium' voretex category in the UK or is that just LHR?

[Turn It Off]

Hay all - Am a Tatc working to Validation so shoot me down if i am wrong - You guys can be as harsh as you like, It will have training value!!

I pulled out the trusty Mats Part 1 and surprise surprise i cannot find anywhere where it defines how far offset an intermediate departure is. Just that the gap is 2 or 3 minutes. Therefore, am i correct to assume that it would have to be declared in unit specific instructions (Mats2) whether or not holds are intermediate.

I remember from a spell at EGLL for OJT that they have points that are not considered intermediate departures and they were clearly outlined in the part 2. Am I to assume that 'unless it says otherwise' that any other hold is intermediate?

This is as much for my help as anyone else coz hopefully the dreaded first board isn't far away!!

Thanks all

[Gonzo]

If it's imperative that a departure rolls immediately, or two minutes, behind a 757 (because of, say, a landing a/c on approach), then the ATCO should have ensured the crew was happy before committing. Yes, the AIP says that the crew should say that they need more time when they receive the clearance, but how many do, in reality?

And 757s are relatively rare at LHR now anyway, so it happens infrequently. Intersection departures tend to be used mainly on 09R, so there's a negligible effect on departure rates. In fact, more time is lost in a/c crossing the runway slowly, and lining up at a snail's pace.

It's interesting to see differing interpretations of vortex. All British crews, and Aer Lingus seem happy 'wheels up' after a 757, and increasingly foreign operators too. However, an AAL 777 wanted two mintues behind a 767 the other day. I asked if it was a company requirement or personal, he replied 'both', and yet a few minutes later another AAL 777 went 'wheels up' after a 744.

[opnot]

Gonzo

At Manch, no British operator flying a B757 behind a departing B757 will accept a wheels off take off clearance they all want 2 mins. Its got to the stage wherebye a B757 of the same company req 3 mins behind a departed B757, because its a different series acft, ie it may be heavier.

Vacate the rwy and I will call you, then becomes the reply

[ATCO Two]

Hi Turn it Off,

You are quite correct - the departure points that are not considered to be intersections for the purposes of increased vortex wake separation are listed in Mats Part 2. At Heathrow these are Blocks 18, 86, and 102 (which is my particular claim to fame as I got the extra vortex wake requirement removed many years ago through the Technical Committee). I am not sure exactly what determines an intersection in terms of distance from the threshold, but a look at the declared take off distances and a bit of subtraction may reveal the answer.

[Gonzo]

Opnot,

If an a/c says to me that he needs an extra minute when he's already lined I'll just leave him there. It takes more than a minute to clear the runway so all round it's actually quicker for us.

[caniplaywithmadness]

Gonzo,

That works fine at LL but would you be happy to leave him there if you were down to single rwy ops with an inbound at 3 miles?

The scenario causes problems for those of us at units which have busy single rwy ops.

[Gonzo]

No, of course I wouldn't be happy. That's why I said 'for us'. I see some at work who should know that one particular aircraft might want extra time, but don't ask, and then get annoyed when they do, start taking it out on the crew and ordering them off the runway. It's a waste of time I think because for one it actually does waste time, and probably gets the crew's collective back up which is not good for CRM.....just before take off is not the time for the flight crew to be thinking how 'arsey' ATC is and not concentrating on other matters.

And surely at a busy single runway airfield and it was 'tight' with an inbound approaching, you'd check if the crew was happy to depart immediately, wouldn't you?:ok:

[mad_jock]

Thanks for the replys.

I must admit was bracing myself for some abuse which hasn't really happened and as someone else is getting some training from the discussion, great. Sad to see though it seems like one of these grey areas which will only get mentioned if anything happens.

On a note I was searching through the Jeppy plates this morning looking for said note and couldn't find the bloody thing. This could of been for several reasons so I will put a bit of work in this weekend and have a look at the master set.

As a wee side note for my own personal reference.

Does anyone know if there is a list of minimums including non-pre approaches at the main airports in the UK?

Its for bad wx days when i am checking the legalities of launching.

I have a feeling I am going to have to sit down and go through all the plates this weekend to produce it for our alts for the routes I fly.

Thanks again

MJ

[Moorsel]

I am wondering why you do so many safety cases in UK, if, at the end of the day, pilots do not trust in published procedures thus compromising the available runway capacity for all users.


What this A320 pilot did is unconceivable. Would pilot and airline associations be willing to recall to this pilot his accountability in delivering runway capacity?

Francesco

[brimstone]

mad_jock - I think your starting point should be the Aerodrome Section of the UK AIP. If you look in the Aerodromes-General part dealing with aerodrome/heliport availability and then move on to the Aerodromes-Specific area this should give you the basics of what you are looking for.

If you can't readily get to a copy the information is available through the CAA or NATS websites.

:8 :8

[Ausatco]

ATCO Two

Australian MATS says that intersections 150 metres or less apart do not attract the extra 1 min wake turbulence penalty.

I don't know if that's Oz-specific or if it comes from ICAO.

Our regulator has a policy of harmonising with ICAO (as distinct from doing it our way in bygone eras), so I suspect it may be in DOC 4444 or some such.

Would be interested to hear if you find an ICAO reference.

Cheers

AA

[Moorsel]

I have found no reference to wake vortex in ICAO Annex 14-Aerodromes-. The last chance would be in Doc 9157 - Aerodrome Design Manual - .

However I think there is no ICAO provision on holding bay position and wake vortex. ICAO is well know and often criticised for not having an adequate policy on wake vortex.

I know that the UK-CAA has established 4 wake vortex categories (instead of 3 as an ICAO) which apply all over the country but not in busy airports where there are 5 wake vortex categories. US has got 3 wake vortex categories which also differ from ICAO and a specific wake vortex category for B757.

De facto there is no common standard worlwide for wake vortex. It is normal that each airline could have its own internal policy about wake vortex.


How many wake vortex categories have you got in Australia and what are the low and upper values for each class?

Thanks

Moorsel

[missy]

In Australia we treat the B757 as a heavy if they are the lead aircraft and as a medium if the are following. Mind you we get one per week in Sydney which is a pity 'cause I think they are a nice aircraft.

[vintage ATCO]

Try ICAO Doc 4444 Ch5 and Doc 9426 PtII Sec5 Ch3.

Not sure what you are after though.


VA

[Ausatco]

Moorsel,

Sorry about the delay - been camping for a few days. No Internet where I was, just sun, surf, sand and the glorious Aussie bush ... but enough of that:D

We use three weight categories for wake turbulence separation in Australia:
Heavy >136,000kg
Medium 7,000kg to 136,000kg
Light <7,000kg

There is a kind of sub-category which we call Light-Medium (terminology is not in MATS), weight <25,000kg. Light behind Light-Medium has no wake turbulence separation applied. That is the only rule for that sub-category.

AA