ssides
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Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 12:08 am

I have flown out of DFW several times in the past month and have noticed that ATC seems to be sending aircrafts out on takeoff at a super-fast pace. It almost seems like the next aircraft is revving up its engines as soon as the aircraft before it leaves the ground. Is DFW notorious for this pace of takeoffs, or am I just now noticing it?
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LHR340
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 1:59 am

It's probably normal, at LHR as soon as an aircrafts wheels leave the runway, the next aircraft is cleared for takeoff (depending on aircraft and weight ofcourse) I noticed this about a year ago, a little scary but works. They are less than a minute apart.

LHR340
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DIA
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 2:02 am

I can say that ATL seems to do this as well. Very tight.
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aa61hvy
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 2:33 am

Its common do prevent ground delays as soon as one is taking off one is lining up, its cool-never a dull moment.
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Bobs89irocz
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 3:43 am

This is the first i have herd of this at DFW, i use to spot there for about 3 years back before 9/11 and they never did this. Here at ORD when one airplanes mains are just about to lift off the ground the plane behind him is powering up TO on the RWY. Very cool sight to see.
 
jhooper
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 5:15 am

You might encounter a 2 minute delay if the aircraft that took off is a "Heavy" aircraft.
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PSAjet17
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 5:19 am

Remember, the primary method of spacing within ATC is distance and altitude, not time. Once a departing aircraft has rotated and established on a positive rate of climb, the next aircraft can be cleared for takeoff. By the time this plane reaches rotation, the first aircraft is 2 to 4 miles ahead and at a climbout speed (210-250kias) while the second aircraft is gradually accelerating from VR. 5 mile seperation is easily established by the time both planes reach any similar intermediate altitude.
 
InnocuousFox
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 6:28 am

On a runway that is slated for "departure only" (e.g. 18L or 17R) at a particular time, ATC will follow this pattern (aircraft departed in numerical order):

AC1, winds @yy, fly heading 170, runway 18L clear for t/o.
AC2, runway 18L, position and hold
AC0, contact departure

AC2, winds @yy, fly heading 190, runway 18L clear for t/o.
AC4, runway 18L, position and hold
AC1, contact departure

AC4, winds @yy, fly heading 165, runway 18L clear for t/o.
AC5, runway 18L, position and hold
AC2, contact departure

Notice the flow. By the time AC1 was off the ground, AC2 was pulling onto the runway and the prior departure (AC0) was passing through an altitude where it was to be handed off to departure (~2000-4000 AGL)

The only time you will hear a break in this at DFW is when they will tell a positioning aircraft that someone will be crossing downfield - an arrival off of 18R. As soon as the aircraft that is departing passes where the arrival is holding on a taxiway, they will clear the aicraft to cross... and THEN (when the crossing AC is clear) give the t/o clearance to the one in position. Usually, it doesn't matter because the a/c that is positioning only just gets into position by the time the arrival has crossed. At times, you will see them hold 2 or 3 aircraft on separate taxiways next to the departure runway and then have them ALL cross behind a departure! That's kinda cool...
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atcboy73
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 12:55 pm

Let me see if I can explain this with out making a fool out of myself. Im an air traffic controller so you would think I should get it right. The only thing is I don't work at DFW but we all use the same rule book.

Runway separation is the same everywhere in the US. Ill talk jets since that is what I think you are referring to.

When ever a jet is involved your runway separation has to be 6,000ft and airborne. Once airborne, course divergence is used to separate, meaning the second departure has to be assigned a course that differs by 15 degrees from the previous departure.

Visual separation can also be used. I would use this if I needed to send both planes out on runway heading. This meaning the pilot of the trailing a/c must maintain visual with the preceding a/c.

These are the two used mostly at DFW.

Or you could always wait until you would have 3 miles, which is IFR separation.


Hint: Something else you might want to watch for. When a HEAVY departs and there are planes waiting to cross the active runway, you can almost always bet the controller will cross them after the HEAVY departure. This is done because of the wake turbulence separation requirement of two minutes or five miles. The next departure needs to wait for the wake to dissipate and its a great time to get a/c across with out any delay to the other departures waiting to take off.

Hope I didn't confuse you guys.
 
crberkley
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RE: Rapid Pace Of Takeoffs At DFW?

Fri Jan 23, 2004 1:07 pm

atcboy73- just passing through on this post, and I have to say, you clarified exceptionally. I have always wondered about the separation between aircraft, until today..Thanks

crberkley