Parallel Runway departures, Large Vs Small

FM_Weasel Trusted Member

Just thought about a hypothetical situation where a controller was gigged for allowing a small to take off from a parallel runway after a large had departed. All other required forms of separation were fulfilled in this example, this is just referring to the Wake Turbulence application.

The two runways do not have even thresholds. Since the small took off from a runway that starts further down, it was determined that it counted as an "intersection departure" and a 3 minute hold for Wake Turbulence was required, since the large departed first and the two runways are less than 2,500 ft apart.

However, 3-9-7 specifies that the 3 minute hold is only necessary on parallel runways when the preceding aircraft is a Heavy/B757 (ref 3-9-7 a(2)). Notice that paragraphs a(1) and a(3) don't say anything about parallel runways

Now, there's a note under 3-9-7 a(2) that says:

NOTE
Parallel runways separated by less than 2,500 feet with
runway thresholds offset by less than 500 feet shall apply
para 3-9-6, Same Runway Separation, subpara f.

But 3-9-6 f doesn't apply to this situation either, because again, the preceding departing aircraft is a LARGE not a Heavy/B757.

Seems like there's no reason to believe that a deal occurred, so why would I come up with such a thing? Am I just :p:p:p:p:p:p:p crazy?

Please share your thoughts and interpretations.

GLF5 Senior Member

I have this situation at my facility. One runway is staggered from the other. How far? Who knows, it's kept a secret I guess. Would I say it's more than 500ft? Yes. However, we do not apply 3 minutes for the situation you described. The only time that runway gets tied up is if a heavy departs the parallel, as the runways are less than 2500ft.

garlandatc Junior Member

7110.65 3-8-3
Really they got gigged. Break out the ref to see what they say.

atcguruaf Rico Suave AZ

you must be, as you put it, just crazy.

Roddy_Piper Resident Knucklehead Vegas baby

there is no wake turbulence separation on parallel runways when dealing with large and small. there isn't even a crossing paths after departure rule that would apply.

deal or no deal...i say no deal.

k5freek Newcomer

would only appy to Heavy and parallel rwys less 2500