Need perspective: WAKE TURBULENCE

[201Steve]

?

[Rick Junkin]

I had this happen. I asked for a high speed taxi to the “captain’s bars” where the 73 touched down and continued with a rolling takeoff from there. Tower had no problem with it.

Cheers,
Rick

[47U]

Depends on the winds.  If there’s a chance the wake will be blown back across the runway, I’d wait, or do like Rick Junkin (above) and start my takeoff roll at a point past where the 737 landed.

[201Steve]

It’s funny how there are so many little things to think about in aviation. I’ve been reading a lot about wake turbulence accidents lately. I’d never really considered this scenario. All the examples discuss wake turbulence as an event to consider when landing or taking off behind another biggie, when you are both making the same maneuver back-to-back.  I found myself in this scenario yesterday and simply thought, well he’s landing… there will be WT up until just passed touchdown- I considered a slow roll past the touchdown point and then full power past the touchdown point, but it seemed just as simple to wait. I asked tower to let the number 2 behind me go ahead of me (a PC12) and you would have thought I ruined his day. It was not a difficult coordination at all, but his tone insinuated he thought I was a real pu***. It seems based on the results of the poll, maybe it’s true. Haha.  Anyway, I don’t regret the request, but after further consideration, I may elect for simply a slower initial roll and just move past the point in the future, to keep the conga line moving. 

[laytonl]

A slow roll to the touchdown point is a good plan - I’ve done that several times.  However, it’s your choice and what the controller thinks doesn’t matter.  Do what you feel is safe for you.  Lee

[201er]

4 hours ago, 201Steve said:

?

It’s funny, I had this exact scenario twice on my recent trip. 

In Fort Lauderdale, tower instructed me to “line up and wait” before the Southwest 737 on the runway even started to roll for takeoff. Cleared for takeoff before I was even lined up. I noticed a moment after takeoff where my climb flattened out momentarily but otherwise uneventful.

In Louisville, I asked to takeoff once an embraer had landed and was instructed a 3 minute hold for wake turbulence.

In Savannah, they had me takeoff on a crossing runway immediately after a flight of 8 F35s had taken off.

When you play with the big boys, results may vary. Whole different animal if it’s a heavy.

[Hank]

I've asked for 2 minute delay in this exact situation more than once. Including the time a restless airliner back taxied the runway so he wouldn't have to wait for me. I told tower I was ready to go once he got out of my way, before he began his turnaround in front of me.

Then he left, and I asked for a "2-minite wake turbulence delay for the departing airliner."

[Ron McBride]

I hit jet exhaust from a test stand under short final.  At 75’ I hit the exhaust, rolled me over steeply.  Went around and landed on parallel runway. 
 

be careful out there.  
 

[Raymond J1]

 

[Pinecone]

Why do you ask for a high speed taxi to the touchdown point?  I would just do that.  When you are cleared for take off, you have the whole runway to use.  Though, I would taxi at a good pace.

I will NOT roll onto the runway behind a jet that has not started their take off roll, or has just done some.  Some VERY high speed air movement with the jet blast.

[Mooney in Oz]

1. You’re #1 for takeoff, holding short. There is 1 aircraft behind you. It’s a busy day, and there’s a landing 737. Tower clears you for takeoff as soon as the 737 exits the runway.

@201Steve Unless I am missing something or misunderstand, I can't see why you would want to delay or modify your departure as there will be no wake turbulence to consider for the following reasons;

No medium or heavy aircraft has taken off immediately before you.

Assuming this is to be a full length takeoff, the landing 737 approach should arrive at 50 feet over the runway threshold and touch down on the 1,000 foot markers, followed by a roll out to vacate the runway.

Once the 737 has touched down, the wings are no longer generating lift and the 737 is no longer flying, therefore there shouldn't be any wake. Your takeoff roll will take you to about the 1,000 foot markers at rotation where it should all be over. If you are still worried about it then just make it initially a slow takeoff so that you rotate further past the 1,000 foot markers.

Apologies if I have misunderstood.

[Rick Junkin]

2 hours ago, Pinecone said:

Why do you ask for a high speed taxi to the touchdown point?

My thought was it eliminated any questions the tower controller might have had  when he saw me not accelerating down the the first 1,000’ of the runway. He was busy and had other things he could be concentrating on without the possible distraction of seeing my lower speed initial roll and the additional time it would take and possibly thinking I was aborting. In hind sight my call would have been better as an advisory call to the tower telling them what I was doing rather than a request.

I judged it appropriate at the time, but I could also argue that my additional radio call was unnecessary and might add confusion since it was non-standard and unexpected. I agree, once cleared for takeoff I own the runway and can execute how I please. When I’m going to do something different than what is standard or expected I communicate to let people know about it.

Do we have any ATC folks here that can weigh in? Is this useful information or just chaff on the tower frequency?

Cheers,
Rick

[201Steve]

@Mooney in Oz you are tracking, and also re hashing some previously mentioned points. I’ve landed behind and took off behind big jets, just simply not in this scenario so it gave me pause. My thinking, there is potentially WT for 1500’ from begin of runway of which there’s theoretically no way to avoid it, short of time or moving beyond touchdown of the landing jet. I would argue there is potentially WT for a minimum of 1500 ft down the runway and although I would not be airborne yet, it’s still there and if it has the power to turn an airplane upside down, what difference does it make that I’m only going 25, 45, 60…. Knots on rollout. So I waited. 
 

the surprise to me was that the tower controller was annoyed by it, I figured I’m not the only guy who’s thought this before, but based on the poll, maybe I am! Lol
 

 

[Mooney in Oz]

9 hours ago, 201Steve said:

@Mooney in Oz you are tracking, and also re hashing some previously mentioned points. I’ve landed behind and took off behind big jets, just simply not in this scenario so it gave me pause. My thinking, there is potentially WT for 1500’ from begin of runway of which there’s theoretically no way to avoid it, short of time or moving beyond touchdown of the landing jet. I would argue there is potentially WT for a minimum of 1500 ft down the runway and although I would not be airborne yet, it’s still there and if it has the power to turn an airplane upside down, what difference does it make that I’m only going 25, 45, 60…. Knots on rollout. So I waited. 
 

the surprise to me was that the tower controller was annoyed by it, I figured I’m not the only guy who’s thought this before, but based on the poll, maybe I am! Lol
 

 

I don't know what you mean by 'you are tracking' and I haven't deliberately rehashed anything. My comments are based solely on my experiences in over 30 years of professional flying heavy turboprop aircraft into and out of major airports where I have taken off behind many landing jets over the years, including and up to A380 size more times than I care to remember. I have occasionally done the same in my Mooney taking off behind landing medium size jets with no issues.

One other solution to your scenario (which you have already alluded to) is to request an intersection departure from a runway holding point that is well passed the 1,000 foot markers or even the half way point in case of a long landing jet.

I didn't mean to come across that I am right and you are wrong. For the reasons I have already given, I personally would not be concerned, but that's just me.

As PIC, if you have a safety concern in the given scenario, which resulted in you deciding to wait and an annoyed ATC then so be it.  It is their problem to deal with.

[201Steve]

6 minutes ago, Mooney in Oz said:

I don't know what you mean by 'you are tracking' and I haven't deliberately rehashed anything.

It means you are correct and I agree with you. Lol. Put your knife away, haha. 

[Immelman]

What is the wind and how long did the 737 land? That will guide the proper response.

[jlunseth]

I don’t need 3,000 for takeoff, probably half that. If I am on a runway where a 737 is going to land it’s 6,000 at least. All kinds of room to taxi to the touchdown point of the preceding aircraft. I do this at my home airport anyway, but for a different reason. There is an intersecting rwy about a thousand feet down the west facing parallel. When they rebuilt it they put a crown in the intersecting runway. It is exactly at the right spot for the plane to be light on its feet but not really ready to fly so it will throw the aircraft in the air and it will come down again on the far side of the intersecting runway. So I just do a rapid taxi to the intersection and put in power from there. There is about 3,000 feet left, and I do lots of takeoffs and landings on runways that length or shorter at the rural airports in my area, so don’t have a problem starting my takeoff roll from that intersecting runway.

[Pinecone]

17 hours ago, jlunseth said:

If I am on a runway where a 737 is going to land it’s 6,000 at least.

MAYBE

https://en.wikipedia.org/wiki/Santos_Dumont_Airport#:~:text=Over the years%2C the airport's,4%2C340 feet (1%2C320 m).