Class D arrival WT

[MJ]

In a class D tower, is radar wake turbulence separation applicable between a larger VFR a/c followed by a smaller IFR a/c on final?
Why or why not.

Spoiler: Answer from the FAA

the short answer is aircraft would not receive radar separation from the VFR tower, in accordance with 5-5-4. Chapter 5 is radar separation and VFR tower controllers are normally not operating under Chapter 5, Radar. However, wake turbulence procedures still apply in accordance with 2-2-19&20 and 3-10-3, which are advisory in nature. The inbound IFR would receive the approach clearance from radar approach control and communication would be transferred to the tower (typically, at least 7 to 10 miles out). Radar Approach may not even know what type aircraft is in the VFR pattern. Either way, the requirement would be for the tower to ensure Wake Turbulence advisories with the VFR aircraft.

 

[CaptainObvious]

Using 5 to get 4? How does that work with a C172 following a B737?
It's 3 miles, increasing to at least 4 miles when the B737 crosses the threshold.

I'm speaking faster behind a slower in that example and compression on final in that situation. If you can point me to where you can use 3 for WT sep I'd appreciate it. Because the only numbers I know are a hard 4 miles for small behind a large

 

[rugbydog11]

3-10-3 is specifically about runway separation and when mandatory cautionary advisories need to be done. It doesn't negate the minima for 5-5-4.

 

[Stinger]

I'm speaking faster behind a slower in that example and compression on final in that situation. If you can point me to where you can use 3 for WT sep I'd appreciate it. Because the only numbers I know are a hard 4 miles for small behind a large

5-5-4 h.
WAKE TURBULENCE APPLICATION
h. In addition to subpara g, separate an aircraft landing behind another aircraft on the same runway, or one making a touch-and-go, stop-and-go, or low approach by ensuring the following minima will exist at the time the preceding aircraft is over the landing threshold:
NOTE− Consider parallel runways less than 2,500 feet apart as a single runway because of the possible effects of wake turbulence.
1. Small behind large− 4 miles.
2. Small behind heavy− 6 miles

 

[eltors0]

3-10-3 is specifically about runway separation and when mandatory cautionary advisories need to be done. It doesn't negate the minima for 5-5-4.

5-5-4 has no implications on separation responsibility of the tower in a CDSA environment excluding departure separation when applicable. The example given by OP has nothing to do with 5-5-4.

 

[rugbydog11]

5-5-4 has no implications on separation responsibility of the tower in a CDSA environment excluding departure separation when applicable. The example given by OP has nothing to do with 5-5-4.

I would tend to disagree, as I would consider a class D with a tower "terminal" and if there is a certified tower radar display, the separation stated in 5-5-4 must be maintained, but if there isn't then all is fair.
But once again, I air on the side of safety on all the rules. Now its Saturday, lets crack a cold one with the boys, and forget about work for a bit.

 

[rhombus]

Question:
Is the tower radar certified and responsible for providing radar separation to aircraft?

This.

3-10-3 is specifically about runway separation and when mandatory cautionary advisories need to be done. It doesn't negate the minima for 5-5-4.

Coming from a Class Delta VFR tower that does not provide radar separation, 5-5-4 does not apply to us. What does apply to us is 6-1-5 and aside from the 757, there are no wake turbulence separation minima for a small behind a large on final. Therefore, tower applied visual separation can be used. The only requirement is that we issue a wake turbulence cautionary advisory to the small aircraft as per 3-10-3 b., 2.

 

[MJ]

Class D (nonradar) Tower, no radar authority. The smaller aircraft in-trail is IFR (ILS, visual, whatever). The VFR aircraft is larger.

My arguement:
In Class D separation services are provided to IFR-IFR only.

As far as I know, having radar display is moot. Can't use it for radar separation anyway. 7110.65:Chapter 3 - pointSixtyFiveWiki

And to go a step further, not having a radar display wouldn't change operations in any way. The approach facility is 100% responsible for all IFR separation. Like someone else mentioned, how would they even know what the tower is doing with VFR aircraft in the towers airspace. There are no radar identification requirements for the VFR a/c. Additionally, in a completely nonradar environment, it would be impossible for any of the controllers to see the VFR a/c.

I get the point you're trying to make, but there is no wake turbulence separation between a small landing behind a large on final. It doesn't matter if it's IFR/VFR, VFR/IFR, VFR/VFR, or IFR/IFR. It's just an advisory. 7110.65 3-10-3 Section b, Paragraph 2.

That's definitely not true. My question is specific to (smaller) IFR following (larger) VFR, but there's no debate that there's required sep for IFR-IFR. A class D tower would have no responsibility for that separation though.

 

[rhombus]

That's definitely not true. My question is specific to (smaller) IFR following (larger) VFR, but there's no debate that there's required sep for IFR-IFR. A class D tower would have no responsibility for that separation though.

I was referring to Class Delta VFR towers specifically. I know IFR towers have different rules when it comes to wake turbulence.

As an example, if we have a Cessna IFR visual inbound and a Gulfstream IFR on the ILS and we have both in sight we can simply clear the Cessna to land following the Gulfstream and not have to worry about any wake turbulence issues. Just the cautionary advisory.

 

[Dontbotherme]

Class D (nonradar) Tower, no radar authority. The smaller aircraft in-trail is IFR (ILS, visual, whatever). The VFR aircraft is larger.

My arguement:
In Class D separation services are provided to IFR-IFR only.

As far as I know, having radar display is moot. Can't use it for radar separation anyway. 7110.65:Chapter 3 - pointSixtyFiveWiki

And to go a step further, not having a radar display wouldn't change operations in any way. The approach facility is 100% responsible for all IFR separation. Like someone else mentioned, how would they even know what the tower is doing with VFR aircraft in the towers airspace. There are no radar identification requirements for the VFR a/c. Additionally, in a completely nonradar environment, it would be impossible for any of the controllers to see the VFR aircraft.

The VFR only tower would issue a cautionary wake turbulence advisory (they'd have no way of knowing if they'd have radar separation) and clear both to land/touch and go, etc. I'd go as far as saying that between two IFRs, a non radar VFR tower would have zero responsibility between two IFR arrivals in regards to wake turbulence.
If they're radar certified, the tower would be responsible once aircraft were inside the outer marker for wake turbulence separation.

 

[MJ]

The VFR only tower would issue a cautionary wake turbulence advisory (they'd have no way of knowing if they'd have radar separation) and clear both to land/touch and go, etc. I'd go as far as saying that between two IFRs, a non radar VFR tower would have zero responsibility between two IFR arrivals in regards to wake turbulence.
If they're radar certified, the tower would be responsible once aircraft were inside the outer marker for wake turbulence separation.

That's my conclusion as well. Seems sort of couterintuitive though.

 

[wikdevo]

wow.. there is a lot of misinformation in this thread and only a few who know what they are talking about. How many of you actually work approach control?

small behind a large for an approach controller whether ifr/vfr is 3 increasing to 4 at the threshold. all day, every day, cut and dry. Unless! the large is a B757 it is 4 miles continuous.

if you are a class d tower then you are most likely not even radar qualified so it is not your job to separate aircraft on final.

You also cannot use controller applied separation in lieu of wake turbulence separation.

 

[rugbydog11]

wow.. there is a lot of misinformation in this thread and only a few who know what they are talking about. How many of you actually work approach control?

small behind a large for an approach controller whether ifr/vfr is 3 increasing to 4 at the threshold. all day, every day, cut and dry. Unless! the large is a B757 it is 4 miles continuous.

if you are a class d tower then you are most likely not even radar qualified so it is not your job to separate aircraft on final.

You also cannot use controller applied separation in lieu of wake turbulence separation.

I've worked at Class D's and C's with radar, and VFR tower class D's. I always had a certified tower radar display (CTRD, TDW, DBRITE) and had a test I was required to pass before certifying on local that had this situation on it. I agree with you 100%. I guess this is one that will have to get an interpretation from a region or national. And even if they say I can slam a vfr heavy in front of an IFR small with 0 miles separation, I still won't.

 

[ajmezz]

You haven't lived until you've heard a Chinese student solo ask if the wake turbulence will affect him.

 

[rhombus]

wow.. there is a lot of misinformation in this thread and only a few who know what they are talking about. How many of you actually work approach control?

small behind a large for an approach controller whether ifr/vfr is 3 increasing to 4 at the threshold. all day, every day, cut and dry. Unless! the large is a B757 it is 4 miles continuous.

if you are a class d tower then you are most likely not even radar qualified so it is not your job to separate aircraft on final.

You also cannot use controller applied separation in lieu of wake turbulence separation.

The original question was asking about radar wake turbulence separation in a non-radar Class Delta tower, so the radar wake turbulence rules you quoted from 5-5-4 h do not apply. Radar rules don't apply in a non-radar environment. Plain and simple.

And since there is no wake turbulence separation for a small behind a large in a non-radar environment, tower-applied visual separation can be used. We do it all the time.

 

[Dontbotherme]

Question 2:
Scenario-
You have a C172 in the pattern doing touch and gos. A GLF5 is ready to depart full length before the C172 turns base. You clear the GLF5 for takeoff.
A) Do you say,"C172, traffic a GLF5 departure roll, advise traffic in sight." Make the C172 see the GLF5 prior to giving the wake turbulence advisory and the touch and go clearance.
OR
B) Say something like,"C172, traffic GLF5 departure roll, caution wake turbulence, wind xxx@xx, runway xx cleared touch and go."

 

[CaptainObvious]

Question 2:
Scenario-
You have a C172 in the pattern doing touch and gos. A GLF5 is ready to depart full length before the C172 turns base. You clear the GLF5 for takeoff.
A) Do you say,"C172, traffic a GLF5 departure roll, advise traffic in sight." Make the C172 see the GLF5 prior to giving the wake turbulence advisory and the touch and go clearance.
OR
B) Say something like,"C172, traffic GLF5 departure roll, caution wake turbulence, wind xxx@xx, runway xx cleared touch and go."

We full stop the Cessna or hold him on the runway unless he deviates the 3 minutes for an intersection departure, unless he gets the large in sight.

 

[rugbydog11]

Question 2:
Scenario-
You have a C172 in the pattern doing touch and gos. A GLF5 is ready to depart full length before the C172 turns base. You clear the GLF5 for takeoff.
A) Do you say,"C172, traffic a GLF5 departure roll, advise traffic in sight." Make the C172 see the GLF5 prior to giving the wake turbulence advisory and the touch and go clearance.
OR
B) Say something like,"C172, traffic GLF5 departure roll, caution wake turbulence, wind xxx@xx, runway xx cleared touch and go."

I do the maintain visual.

 

[Dontbotherme]

We full stop the Cessna or hold him on the runway unless he deviates the 3 minutes for an intersection departure

So you basically stop all pattern traffic if a larger aircraft is departing than what is in the local pattern?

 

[Super Salt]

Question 2:
Scenario-
You have a C172 in the pattern doing touch and gos. A GLF5 is ready to depart full length before the C172 turns base. You clear the GLF5 for takeoff.
A) Do you say,"C172, traffic a GLF5 departure roll, advise traffic in sight." Make the C172 see the GLF5 prior to giving the wake turbulence advisory and the touch and go clearance.
OR
B) Say something like,"C172, traffic GLF5 departure roll, caution wake turbulence, wind xxx@xx, runway xx cleared touch and go."

Either have the Cessna report traffic in sight and tell him to maintain visual separation, caution wake turbulence OR clear him low approach only.

 

[GO]

So you basically stop all pattern traffic if a larger aircraft is departing than what is in the local pattern?

Given the aircraft wants touch and go specifically then yes basically stop him on the runway and call their departure or manipulate their pattern to insure time requirement. Unless GLF5 departure is insight and issue cautionary with option clearance.