lke2fly
Topic Author
Posts: 52
Joined: Tue May 03, 2011 3:47 am

Airline Runway Departures

Tue Aug 21, 2012 5:30 am

My question is and I hope I word this correctly. What is the time lapse between aircraft leaving the runway. Example if a A320 departs the runway how soon can the next aircraft take off. I have seen some airliners take off and the other airplane doesn't wait on the runway, he turns into the runway from his holding position and takes off without waiting. Is there different times depending on size of the airliner that just departed before the other one takes off?
 
IAHFLYR
Posts: 3941
Joined: Sat Jun 25, 2005 12:56 am

RE: Airline Runway Departures

Tue Aug 21, 2012 5:57 am

There are many variables to consider in order to answer your question. If the same weight category of aircraft does not require additional wake turbulence separation then it is as soon as the first aircraft is airborne the next can start take-off roll.

Then there is the standard 3 NM RADAR separation with aircraft flying the same initial heading immediately after departure. The second airplane when both are similar types would have to wait until the first aircraft is about 1/2 NM past the departure end of the runway (depending on the length of the runway) in order to establish 3 NM separation when the second aircraft is RADAR identified.

Then the 15 degree divergence rule where the second airplane can start to roll just about immediately after the first is airborne if their courses diverge by at least 15 degrees.

Don't forget the use of visual separation either, that helps get things moving quicker at times also.

So many ways to keep airplanes moving at a controlled airport, just be creative if you're the local controller!  
Any views shared are strictly my own and do not a represent those of any former employer.
 
lke2fly
Topic Author
Posts: 52
Joined: Tue May 03, 2011 3:47 am

RE: Airline Runway Departures

Tue Aug 21, 2012 10:47 pm

Thank you very much IAHFLER for clearing it up. Now I understand how runaway departures work between aircraft. Sorry if I didn't the question correctly.
 
AirframeAS
Posts: 9811
Joined: Thu Feb 05, 2004 3:56 pm

RE: Airline Runway Departures

Tue Aug 21, 2012 11:06 pm

Quoting IAHFLYR (Reply 1):
Then there is the standard 3 NM RADAR separation

I thought it was a 5 mile separation.... or is that for landings??
A Safe Flight Begins With Quality Maintenance On The Ground.
 
RyDawg82
Posts: 833
Joined: Fri Sep 14, 2001 8:30 am

RE: Airline Runway Departures

Tue Aug 21, 2012 11:24 pm

Quoting AirframeAS (Reply 3):
I thought it was a 5 mile separation.... or is that for landings??

In the USA:
The only general instance that 5 NM would be required would be a non-heavy jet departing behind a heavy jet.
A non-B757 departing behind a B757 would require 4 NM.

There are a whole host of other specific situations in which miles or time would be required after certain departures; however, the general rules have been outlined above.

Hope this helps,
Ryan
You can take the pup out of Alaska, but you can't take the Alaska out of the pup.
 
IAHFLYR
Posts: 3941
Joined: Sat Jun 25, 2005 12:56 am

RE: Airline Runway Departures

Wed Aug 22, 2012 12:48 am

Quoting AirframeAS (Reply 3):
I thought it was a 5 mile separation.... or is that for landings??


Nope, in the terminal arena it is 3 NM for departures if flying the same initial course climbing to the same altitude and there is no wake turbulence increase required. It's very tricky with many different ways to apply separation between like type departures.

There is a 2.5 NM requirement for landing at some airports using reduce runway occupancy times if no wake turbulence separation is required, then you have visual which is basically just give the first airplane enough room to exit the runway before the next crosses the landing threshold. Does your head hurt yet?

In the enroute environment, 5 NM is the standard for same altitude as well as for transitioning from the terminal to enroute....wow am I glad I am about to retire!!
Any views shared are strictly my own and do not a represent those of any former employer.
 
Mir
Posts: 19092
Joined: Mon Jan 05, 2004 3:55 am

RE: Airline Runway Departures

Wed Aug 22, 2012 3:33 am

Quoting AirframeAS (Reply 3):
I thought it was a 5 mile separation.... or is that for landings??

That's for enroute airspace (that controlled by a Center rather than an Approach/Departure facility).

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
LONGisland89
Posts: 542
Joined: Sun Jan 22, 2006 3:34 am

RE: Airline Runway Departures

Thu Aug 23, 2012 6:35 am

Quoting lke2fly (Thread starter):
Example if a A320 departs the runway how soon can the next aircraft take off. I have seen some airliners take off and the other airplane doesn't wait on the runway

The answer to your example is 6000 feet and airborne. This separation needs to exist by the time the following aircraft begins its takeoff roll. The use of anticipated separation allows a controller to clear an aircraft when the separation does not exist with the preceding aircraft, if there is reasonable assurance it will exist by the time the takeoff roll begins.  
 
rotation18L
Posts: 32
Joined: Sat Jun 23, 2001 11:30 am

RE: Airline Runway Departures

Sat Aug 25, 2012 8:35 pm

Based on what's being described here, am I assuming all of these departure variables have to be known by departure controllers right off the top of their heads? To use wake turbulence variables as just one example, are you saying that departure controllers must know the varying wake turbulence characteristics of every aircraft departing their commercial facility in order to know the minimum separation requirements that must come into play between any given departing aircraft and the corresponding holding aircraft?

If that's true, that's amazing!!!   
 
YYZatcboy
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Joined: Fri Apr 22, 2005 2:15 am

RE: Airline Runway Departures

Sun Aug 26, 2012 2:41 am

ATC memorize lots of things. On my tour to YEG center they told me that they have to memorize aircraft performance categories (A-D) as well as wake turbulence categories. they also memorize the names, frequencies and lat/long of every naviad and fix in their airspace as well as the names and radials of all airways in their sector. THEN they have to memorize all of the appropriate frequencies for handoffs and the like. Keep in mind that they are often checked out on 3 or more sectors and that gives you an idea of what they have to memorize.
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