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Posts: 598
Joined: Sat Oct 02, 1999 8:49 am

Departure: Runway Assignment At Busy Airports

Wed Aug 07, 2002 8:05 am

Hi everyone,

I have noticed by listening to my scanner that in busy airports with multiple departure runways the runway assignment doesn't come until at a relatively late departure stage concerning takeoff planning.

The best example I can think of is Chicago O'Hare, this would be one real scenario: ATIS reports "departing runways 04L, 09L, 14L, 32L, 32L at T10". That's 5 different takeoff options. When listening to clearance delivery, a departure procedure is assigned, followed by a flight route and/or "as filed", the initial altitude, flight level to expect, and squawk, but NO runway assignment yet. Then it's ramp control for pushback clearance. No runway assignment. Ground metering to report "ready to taxi". No word on what runway yet. It's not until ground control when a runway is assigned, many times resulting in "Request 32L (longer runway), we're pretty heavy today"...

Why are departure runways not assigned earlier, for example with clearance delivery? Doesn't this require a little bit of unnecessary guessing by the crew? How about performance issues? If you're assuming ATC will assign a certain runway and in the end it turns out it's something else, is it fast and easy to reload FMS takeoff runway data and performance or do these new calculations take an extra while?

Airline pilots replies are really appreciated, but of course all replies are more than welcome.
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modesto2
Posts: 2669
Joined: Sun Jul 16, 2000 3:44 am

RE: Departure: Runway Assignment At Busy Airports

Wed Aug 07, 2002 9:06 am

While these late runway assignments may apply to ORD, they do not apply to all major airports. I am most familiar with SFO and LAX...so I will speak about those. LAX mainly uses 24L and 25R for departures. Northbound flights generally use 24L while many eastbound flights use 25R. At SFO, southbound flights generally use 1L while eastbound aircraft use 1R. Heavier aircraft use 28L/R for departures, regardless of destination. These are just examples of when runway assignments can be fairly accurately guessed. I think part of the issue with late assignments is traffic flow. Traffic jams come and go and an aircraft may taxi 20-30 minutes after receiving a clearance. A lot can happen during this time period. Late assignments give the controllers more freedom to conveniently assign departure runways.
 
donder10
Posts: 6944
Joined: Sun Oct 21, 2001 5:29 am

RE: Departure: Runway Assignment At Busy Airports

Wed Aug 07, 2002 9:08 am

The runwat is given in the departure clearance "Speedbird 179 cleared as file to JFK,Compton2Foxtrot'The 2F gives the SID which has a different code for each runway.
 
timz
Posts: 6101
Joined: Fri Sep 17, 1999 7:43 am

RE: Departure: Runway Assignment At Busy Airports

Wed Aug 07, 2002 10:56 am

The above usually isn't true in the US.
 
jhooper
Posts: 5560
Joined: Thu Dec 13, 2001 8:27 pm

RE: Departure: Runway Assignment At Busy Airports

Wed Aug 07, 2002 12:03 pm

I am mostly familiar with DFW. Eastbound departures are normally issued 17R, while Westbound departures are normally issued 18L.
Last year 1,944 New Yorkers saw something and said something.
 
Bjones
Posts: 122
Joined: Sat Feb 16, 2002 11:46 am

RE: Departure: Runway Assignment At Busy Airports

Wed Aug 07, 2002 12:04 pm

Although the runway isn't given until taxi clearance is requested pilots usuallly have a pretty good idea which runway they will get based on where they are parked and where they are going after departure. In most cases it doesn't take more than a few keystrokes to input the takeoff runway/departure routing into the FMS. As far as performance data it doesn't take long to calculate because there usually is either quick reference charts or the FMS in some aircraft will calculate it.
 
America West
Posts: 1151
Joined: Sun Mar 25, 2001 6:54 am

RE: Departure: Runway Assignment At Busy Airports

Wed Aug 14, 2002 7:59 am

The runways at CMH are usually assigned based on where the airline's gates are located.

10R/28L
Continental (A)
Continental Express (A)
Air Canada (A)
America West (South B)
America West Express (South B)
Northwest (South B)
Northwest Airlink (South B)
US Airways (A)
US Airways Express (A)
American (East B)
American Eagle (East B)

10L/28R
America West Express (North B)
United (North B)
United Express (North B)
Southwest (C)
Delta (C)
Delta Express (C)
Delta Connection-Comair (C)
Delta Connection-ACA (C)
American (East B)
American Eagle (East B)

( ) = Concourse
 
LAXspotter
Posts: 3227
Joined: Sat Jan 27, 2007 4:16 pm

RE: Departure: Runway Assignment At Busy Airports

Wed Aug 29, 2007 12:04 pm

Quoting Modesto2 (Reply 1):
, they do not apply to all major airports. I am most familiar with SFO and LAX...so I will speak about those. LAX mainly uses 24L and 25R for departures

Although this is true, one will realize that it has to do with relieving airport congestion. Many runway assignments are to ease the clogging of aircraft at one side of the airport. Many times, at LAX during specially during Rush hour, aircraft will come from Terminal Four, Five and Six and taxi to 24L, the reason is that the South Field of LAX usually has more aircraft, and the north field has lesser number of aircraft. So, you will see many American and Delta aircraft including American Eagle taxi to 24L. LAX, is definetely one of the best free-flowing airports in the world, we're blessed with good weather four parallel runways mean, they can launch departure after departure. I have never witnessed a lineup at LAX, with more than six aircraft, and this at the 4th busiest airport in the world by movements.

Quoting America West (Reply 6):
The runways at CMH are usually assigned based on where the airline's gates are located.

usually how it works at most airports, but at larger airports aircraft will taxi to runways farther away than the closest one to prevent long queues for takeoff.
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