Wake turbulence with pattern traffic

[creepstreets]

We had a scenario come up, and there was a bit of a debate regarding wake turbulence for an aircraft in the pattern.

We had a large that was on a visual approach to the runway on right downwind. At the same time, we had a small on left downwind in the pattern. The large turned base, and we pointed out the traffic to the small so that he could follow the large in to the runway. If the small did NOT get the large in sight, would the small require the 4 miles in trail behind the large in 7110.65 5.5.4I?

 

[Acquired Taste]

Approaches OR directly behind. Directly Behind is defined as following flight path of the lead aircraft over the surface of the earth. The cautionary from 3-10-3 is in addition to this.

No, that's IFR separation. The separation between an A388 super arrival and a C172 doing pattern work is don't trade paint and a cautionary wake turbulence advisory.

 

[rhombus]

It really depends what class of airspace you're working. Class B and C you would apply 5-5-4. Class D issue a wake advisory and just don't have a deal on the runway.

 

[Phanatical]

Somebody clear this up for me. (Class D airspace). A large and a small doing patterns to the same runway.

A large aircraft is doing patterns and is on the go. A skyhawk is also doing patterns and turns base to follow the large. My OJTI said I need to start the 3 min timer when the large rotates off the runway to provide wake turb sep for the VFR skyhawk because he is an intersection departure when he does his touch and go or get the large in sight for the skyhawk. At my last facility I just issued a cautionary to the skyhawk. Is my OJTI correct in requiring the 3min/visual or do I just need the cautionary?

As long as the 172 gets the large in sight, you can instruct the Skyhawk “Maintain visual separation, caution wake turbulence.” After that you don’t need the timer. It’s not strictly a cautionary since you are instructing to maintain visual (7110.65 3-9-7-b-3)

 

[sizziano]

Somebody clear this up for me. (Class D airspace). A large and a small doing patterns to the same runway.

A large aircraft is doing patterns and is on the go. A skyhawk is also doing patterns and turns base to follow the large. My OJTI said I need to start the 3 min timer when the large rotates off the runway to provide wake turb sep for the VFR skyhawk because he is an intersection departure when he does his touch and go or get the large in sight for the skyhawk. At my last facility I just issued a cautionary to the skyhawk. Is my OJTI correct in requiring the 3min/visual or do I just need the cautionary?

3 mins or visual as Phanatical said

 

[rugbydog11]

I stand corrected. I never realized those notes were in there to apply to 5-5-4 minima but that's pretty dumb. Let's take a look at DAB for example. You think when they have 10 in the pattern on 25L and a large is coming in on 25R, they just extend everyone so to next arrival after the large is 4 miles in trail? They are a class C and the runways are approx 1600 ft apart.

If they are in the pattern, and can't get pilot applied, it's time for them to full stop.

 

[A2J]

Approaches OR directly behind. Directly Behind is defined as following flight path of the lead aircraft over the surface of the earth. The cautionary from 3-10-3 is in addition to this.

They do not reference each other. So, that doesn't make sense that "it's an addition".

5-5-4 is for approaches and aircraft in a radar environment. Not applicable to the pattern aircraft.

No, that's IFR separation. The separation between an A388 super arrival and a C172 doing pattern work is don't trade paint and a cautionary wake turbulence advisory.

Yessir

 

[Jacrooster]

If you have a Large departing and a small on an instrument approach to the same runway and that small reports the large in sight on a 1 mile final can you give the spiel and give T & G clearance even though they can’t really mitigate their wake turbulence because they’re flying a established approach?

They can mitigate their wake turbulence in theory. The idea is that they would adjust their flight path to ensure they touch down early and make sure they rotate prior to where the departure rotates, this climbing above their wake turbulence. This was taught in private pilot ground school and wouldn't be surprised if it's in the AIM somewhere for how pilots should operate with regards to wake turbulence.

This is assuming the small has the departing large aircraft in sight and you issue a cautionary advisory.

 

[NotKC]

That and not all D towers have a radar to apply this sep

 

[MJ]

That and not all D towers have a radar to apply this sep

No D towers have a radar, they have certified tower displays.

I've never worked a class C but if someone is doing pattern work at a Class C airport, are they radar identified?

A tower in a C* provides radar services, so yeah they are positively id'd.

*there are exceptions, where the tower is within a C airspace but is a D surface area, so they don't provide radar services. pretty sure all usaf towers w/ approaches are like that

 

[Termine]

How are they radar identified?

5-3-2a.

I’m not “radar certified”

Have you ever in your life taken the radar quals CBI? Congrats, you're radar certified.

 

[A2J]

If the small is just landing, it's a caution WT. Approving a touch and go would require visual and caution (3-9-7 b3). In the unlikely scenario you can't get visual, then you just need 3 minutes (3-9-7 a2) since a touch and go is considered an intersection departure.

 

[Acquired Taste]

I understand that it's in the radar separation section which is synonymous with IFR but wake turbulence affects everyone. You make a good point.

It doesn't make sense to me to have wake turbulence separation by minutes for departing VFR aircraft but on final it doesn't matter let them get blown away.

My question to you is, do you provide that separation between IFR aircraft or TO an IFR aircraft. Example, you have a IFR small on an instrument approach. Tower has a heavy in the pattern. They base their VFR heavy in front of your IFR small. Do you need to apply 6 miles of separation or does it not matter because the heavy is VFR?

Doesn't matter. That's tower's traffic. Technically there's nothing stopping them from basing the heavy right in front of your guy no matter how dumb it is, as long as they say caution wake turbulence to the IFR small of course!

Edit: so yes, the separation is only applied IFR to IFR.

 

[ManBearPig]

Doesn't matter. That's tower's traffic. Technically there's nothing stopping them from basing the heavy right in front of your guy no matter how dumb it is, as long as they say caution wake turbulence to the IFR small of course!

Edit: so yes, the separation is only applied IFR to IFR.

So that's not necessarily true. We went up to the top with this exact thing. If the heavy is in the pattern at a VFR tower, it's true. If they are in the pattern at a Class C airport, they are receiving radar Class C services, and that arrival needs wake separation with the heavy or large in the pattern.

 

[HammerHead]

It really depends what class of airspace you're working. Class B and C you would apply 5-5-4. Class D issue a wake advisory and just don't have a deal on the runway.

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I was digging and this is the same thing I found. You're exactly right, depends on what airspace you're in.

 

[NotKC]

Ok I clearly don't know what synonymous means lmao that's not what I meant at all.

What I was mostly getting at with that is, in other than class B/C(I now know to specify), we supposedly do not have to provide wake turbulence separation to IFR if the preceding aircraft is VFR. Is this correct?

I'm generally asking because at this point I'm not sure.

There is no separation standard between ifr/vfr aircraft for class d operations. Regardless of the order they arrive. Generally speaking, vfr aircraft arriving to class d airports are not radar identified and you couldn't apply mileage based separation even if you wanted to.

 

[Termine]

Radar sep is a type of IFR sep.

And it's also a type of VFR sep, in those situations/airspaces where VFRs are provided separation.

 

[A2J]

We're talking about Class C pattern traffic here. A VFR departs and is in the pattern; they fly a tight downwind for whatever reason and their target gets close to the target of an IFR guy short final.

Class C services include separation between the IFR and the VFR. If someone asks LC "what separation were you using" of course they will say "tower visual." Again, visual separation (tower or pilot) requires the assurance of other separation before and after the visual separation. What separation was LC using before visual? Target resolution. Target resolution is a form of radar separation and requires that both aircraft are (or are about to be) be radar identified. How was the VFR pattern traffic identified? The TRACON sure as hell didn't identify them using 5-3-2a because the TRACON never received a rolling call. So LC has to have identified them somehow.

I'd say SRS before and after visual

But I only work at a class D so my life isn't this complicated with WT

 

[ManBearPig]

You can transition from SRS directly to tower visual if you have the inbound in sight from the moment the pattern guy leaves the runway. You're right, in many/most situations that will be the case. But I can come up with perfectly plausible and legal situations where you don't have the inbound in sight at the moment the VFR leaves the runway.

In Class C we must separate IFRs from VFRs. Defined minimum separation at all times, 500' or target resolution or visual, not just WT sep when the small is passing behind. Yeah, if the VFR has just rotated and the IFR is on a five-mile ILS then obviously they aren't going to hit. But "come on, obviously they aren't going to hit" is not an approved form of separation. Target resolution is an approved form of separation.

There's runway and anticipated separation....

Yes.


I agree.


I disagree. Proper application of 5-3-2a/b/c or 5-3-3a/b/c/d is necessary and sufficient to consider an aircraft radar identified. The identification process is entirely contained within those paragraphs. There is a separate requirement to "inform" the pilot when initial radar identification is established, but that is an informational requirement and nothing more. It does NOT have any procedural significance. Not saying "radar contact" will not lead to a loss; their radar identification is established as soon as you have completed one of the seven radar ID requirements.

In my experience, the FAA disagrees. I know because they wouldn't give me a time off award or even a reach around for wrangling in a 4 ship F16 flight which start burst, and did their best to hit a B1900. I forgot to say "radar contact" as I identified each primary. Why do we say "radar contact" to everyone in approach if we don't have too????

Glad to hear you aren't saying "radar contact" to each pattern plane. Man you would sound dumb.

Curious how you handle aircraft on an IFR flight plan, in the tower pattern. You keep them all 3 miles apart?

 

[MJ]

Can you point to where the book says that?

I mean obviously you do it, I do it, we all do it. We provide same-runway sep because we have to and I'm not saying we shouldn't... but what's the textual justification for providing SRS between two VFRs at a Delta? Putting the pieces together, same-runway separation is a kind of separation. It's right there in the name. And according to the pilot/controller glossary, at a Delta there is no separation service provided between VFRs.

Just one of those things that they haven't gotten around to spelling out in the book because nobody has been annoying enough to force them to, I guess.

There are services provided defined by airspace requirements, and services that are provided that are not defined by airspace requirements. Runway sep is a requirement regardless of airspace, and the "no separation service" you're referencing is in regards to airspace requirements.

 

[Somenewguy]

Runways are part of the earth and are not considered or included in airspace
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“from the surface” not “including the surface”

This argument doesnt really hold up to scrutiny.

If you're 2000' from the runway threshold and airborne in a class delta, you are no longer on the surface, so I can land a 747 behind that Cessna right?

Or to put it another way, a landing aircraft can cross the runway threshold with another aircraft on the runway but as long as it's airborne I don't have to apply any separation?


Everyone claims the 7110 was written by lawyers but it was mostly written by a bunch of FAA management/staff support types who "fixed" problems haphazardly as they arose. It is written with the assumption that the person reading it can infer quite a bit of the practical application aspect and avoid using rules in situations where it would compromise safety. Unfortunately most people are kind of stupid so they find new ways to fuck things up while still thinking that theyre following the rules. As a consequence the rule book has to get bigger every year because it doesn't explicitly say what to do in every situation.