Sequencing IFR arrivals and circuit traffic in Canada - Wake Turbulence question

[Jerricho]

A situation occured yesterday that had me scratching my head and being new to North America I though I would throw it our there for thoughts (I'm kinda hoping cossak could shed some light ;) ). Please don't view this as a witch hunt, just a discussion for my understanding.

When I am vectoring aircraft for approaches, I am required to provide wake turbulence separation. Yesterday I had the situation of DC9 being followed by a Beech Baron BE55, both IFR scheduled arrivals. Now, the require wake turb separation is 4 miles (light behind a medium). The tower also had a military Dash 8 (also a medium) VFR in the circuit doing touch and go's. In the 4 mile gap I had provided between the DC9 and BE55, the Dash-8 was squeezed in. Now, obviously this wasn't providing the Baron with the recommended 4 miles. Being new round these parts I turned to one of the locals sitting next to me and asked what the situation was. He replied "Oh, the Baron would have been issued a cautionary". I scratched my head. My reply what if he wasn't happy with his now reduced wake turbulence separation from the Dash that's been stuffed in front of him. "Oh, he should arrange his flight to stay on top of the wake or ask to be repositioned"

Am I the only one who sees a minor problem with this?

[vector4fun]

Can't speak for Manitoba, but not unusual in the U.S. So long as the WX is VMC and the Baron can see the Dash to adjust flight path and touchdown point as pilot deems necessary.

[cossack]

Don't get much circuit bashing at YYZ ;) but I'll try and put a tower's perspective on this. It took me a little while to get used to it too.

The wake turbulence cautionary is issued a great deal over here and seems to be an a$$-covering thing. We separate our departures by distance not by time, so we can put a medium 5 miles behind a heavy on departure, as long as we issue a cautionary. This translates into about 90 seconds rather than the 2 minutes required normally. Intersection departures (same categories) until recently required 5 miles not 3 minutes! They finally saw the light on that one!

"OK we're ATC, we're going to do you a favour and sqeeze you in with less than the required mileage, but if we warn you about the turbulence, that's OK. It's up to you to avoid it."

This works fine with competent pilots who are happy with this sort of thing at airports where there is plenty of runway length to allow a long landing, such as YYZ. If you ask someone to land long on a 5000 foot long runway in a Baron, it doesn't give him much room for error, but the onus here is on him to accept it or request repositioning.

In your scenario, I personally would consider it bad controlling to do what you have described, but you and I were brought up with different methods and rules and are adapting to our new environment. Its the North American way, move the metal any way you can. The rules have been modified to allow it, so use them as written.

I don't think there are any more wake turbulence encounters here than anywhere else and the general spacing requirements are a lot less in some cases already. Would you have put a light 4 miles behind a medium at Heathrow? No, didn't think so, but you'll happily do it here. C'est la vie, mon ami!

PS Write it out 100 times - c o s s a c k ;)

[Jerricho]

(Sorry about forgeting the c there buddy ;) )

Thanks for the quick reply. The "being brought up with different methods and rules and are adapting to our new environment" is the reason I had to ask this. I remember being beaten over the head a couple of times at Hurn with the "respect wake turbulence" mantra.

It's the accept or be repositioned side of things I have the issue with. Pilot happily trundling down the approach when he's told he's now number 2 to a whatever joining final ahead, caution wake turbulence. Nice. And, maybe I'm over complicating things, but in this instance, the Dash was on a touch and go, thus now generating vortex on landing and climb out (is that really clutching at straws, I dunno?). Put your Baron down somewhere in between?

Perhaps some of the drivers out there who read this could provide some of their thoughts if this situation occured to them.

[ILS 119.5]

I do not know what the Canadian separation standards are but in the UK there is noe requirement to separate IFR fom VFR. The tower controller will say to the VFR a/c "caution vortex wake reccommended spacing is x miles". It is then up to the VFR a/c to ensure it keeps away from the vortex of the preceding a/c. Quite easy to do. I do not think there is a problem.

[M609]

I have allways wondered why we have to use the standard minute based seperation between all departures (VFR & IFR) , but only give cautionarys to VFR arrivals.

I kinda think that wake "hurts" just as much on departure and arrival.

[Jerricho]

ILS,you obviously have no concept of what the situation being described is and just waded in, totally missing the point. :rolleyes:

You are correct in saying in Class D airspace there is no actual requirement so spearate IFR and VFR. However, go and reas the situation I have described again. 4 mile wake turb gap between sequenced IFR arrivals (medium followed by a light). VFR circuit traffic (another medium), following your logic is told to follow the first medium, no problem there. However, the light at the back of the queue now has less than required wake turb separation from the one it is now following. Issued an advisory, basically putting the onus on him to arrange his flight above the Dash-8 or ask to be repositioned. All this sprung on him at the last minute. That is the problem.

[Barra Tuesday]

Jerricho take it from another expat; don't try to rationalise what goes on here in Canada just do what they do and do what they say!! I found that was the best way to check out in the least possible time and avoid unnecessary heartache. I have found; since checking out, the locals don't like it when you question what they are doing and why they are doing it that way. They also don't like it when you do something that they wouldn't have done - the old "We don't do it like that here" syndrome. Of course just because they don't do it like that here doesn't make it wrong. Interested in your thoughts so far on NavCanada.

[Jerricho]

Barra, check you PMs mate.

[West Coast]

Jerricho

I don't know of a patent answer, from my 'spective it is a moving target. If I was the Baron and I could see the Dash I would be alright with it I imagine as long as runway sep existed. Change the Dash to a 757 and make it KSNA short (5700 ft) and I guess I would balk at it.

[ILS 119.5]

Sorry Jerricho,

After re reading your post I see the problem. My answer would be "co-ordination". The tower person is at fault for turning the circuit traffic in and thus eroding any vortex separation you have established. To me the answer would be a little chat between yourselves to handle the situation.

Rgds

ILS

[DFC]

This is not unusual in Europe. Perhaps one should read the ICAO document on wake turbulence and especially the methods available to pilots for avoiding wake. Situations like this is exactly why they are in there.

In Europe (excluding the UK) it is not unusual to hear;

"Cessna" behind the departing B737 line up and wait.

B737 is airbourne

"Cessna" caution wake turbulence cleared take-off early left turn out approved.

Cessna rolls immediately and is airbourne and turned 100s of metres before the point of rotation of the B737.

or

"Cessna" position number 2 to the B737 at 3 miles make it a tight approach and caution wake turbulence.

Pilot touns in tight behind but well above and lands well beyond the B737 touchdown.

Pilots who are trained in those situations and who encounter such situations on a regular basis have no problem. They often however become frustrated at UK "delays" where they wait for an age so that the ATC can have a big enough gap despite the fact that they could depart immediately and avoide any wake.

Question - was the tower controller talking to the Barron prior to slotting in the Dash or were you still talking to the Barron at the time the other aircraft positioned in front?

Regards,

DFC

[Jerricho]

The Baron was just transferred to the tower. Just as I did it, I thought to my self "What's he going to do with that Dash-8", knowing full well the Dash was in the circuit, and probably not landing. I think that's a big part of this that has me shaking my head. Given the Baron could have "landed long", the Dash was on a touch and go (an I've seen it done with aircraft on a low approach). Kind of restricts exactly where the Baron driver can land his plane.

I guess I have always believed in not springing what could be a nasty little surprise on a pilot at the last minute.

[HEATHROW DIRECTOR]

<<Pilots who are trained in those situations and who encounter such situations on a regular basis have no problem. They often however become frustrated at UK "delays" where they wait for an age so that the ATC can have a big enough gap despite the fact that they could depart immediately and avoide any wake.>>

Ahh.. DFC.. Have you ever seen an aeroplane blown over by VORTEX? I have - and I've also been talking to an aeroplane which went "totally out of control" 10 miles behind a heavier aircraft. Bold pilots may well take chances... but you know the old saying.... And what is an extra minute to get you home SAFELY?

[ILS 119.5]

I have seen an a/c lose control due vortex I have also been in one which was due to my own stupidity and inexperience. It is definately the VFR's responsibility to decide about any vortices however it is the responsibility of the tower and approach controller to ensure these situations do not arise.
As HD says, or similar, it is better to arrive a few minutes late in this life rather than arriving 30 years early for the next one.

[DFC]

Heathrow Director,

Ahh.. DFC.. Have you ever seen an aeroplane blown over by VORTEX? I have - and I've also been talking to an aeroplane which went "totally out of control" 10 miles behind a heavier aircraft. Bold pilots may well take chances... but you know the old saying.... And what is an extra minute to get you home SAFELY?

You seem to miss my point.

I was not encouraging or in any way suggesting that any sane pilot would place their aircraft in a position where a wake encounter is likely. If you read my post, I clearly described the methods commonly used and recomended by ICAO to be used for avoiding any chance of wake turbulence encounter.

Perhaps you should considder the chance of a wake encounter with a C172 departing behind a B747 with UK departure wake separation and flying the same climbout track eg straight ahead and then think of the same aircraft departing with no wait but turning away from the runway before it reaches the point where wake turbulence begins. Which do you think is safer?

Simply - if flying a light I have to go the same way as a B747 with the same altitude restrictions, I want 4 or 5 minutes not 2 however if I can make an early turn to avoid any possible wake I can go immediately!.........get the idea?

Regards,

DFC