uclax
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Easterly Ops At LAX

Sat Nov 12, 2011 4:10 am

Having lived near LAX for several years, I've noticed that easterly winds from an approaching fall or winter storm, such as today, are much more likely to lead to easterly ops than easterly winds from Santa Ana winds, which seem to be much stronger winds. Why is that? Thanks!

[Edited 2011-11-11 20:22:27]
...those who wait for the Lord�s help...rise up as if they had eagles� wings Isaiah 40:31
 
LAXintl
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 4:18 am

It simply comes down to wind component.

LA Center will try to keep LAX on west traffic until the wind component starts impacting performance of departures (5kts tail wind or so) and will flip the airport around as a result.
With LA East traffic there are other negative traffic issues in basin such as at Hawthorne and Santa Monica airports so ZLA if it can will avoid east traffic as much as possible.

As I type this the wind is directly out of the east at 8kts.
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goboeing
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 1:25 pm

Felt strange coming into LAX way high on the BASET arrival with such good visibility.

I myself had never landed east at LAX in such nice weather, except one time when I was a passenger.

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IAHFLYR
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 2:33 pm

Quoting LAXintl (Reply 1):
LA Center will try to keep LAX on west traffic until the wind component starts impacting performance of departures (5kts tail wind or so) and will flip the airport around as a result.
With LA East traffic there are other negative traffic issues in basin such as at Hawthorne and Santa Monica airports so ZLA if it can will avoid east traffic as much as possible.

This may be a stupid questioin, but why on earth would ZLA care about traffic issues with Santa Monica or Hawthorne? They don't control the traffic in to or out of those airports, SoCal does would be the controlling facility.
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LAXintl
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 5:04 pm

Yes SCT must do much of the work but ZLA cares as it ultimately must adjust and then coordinates with the DC command center for the traffic restrictions.

With LAX east flow, the arrival rates at LAX and other basins airport change for the worse, with arrival and departure routings shifting that effect flows in the national airspace system. One interesting reason why they try to avoid going East, is that SMO will be forced to close if LAX goes low IFR in the east configuration.
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IAHFLYR
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 5:30 pm

Quoting LAXintl (Reply 4):
Yes SCT must do much of the work but ZLA cares as it ultimately must adjust and then coordinates with the DC command center for the traffic restrictions.

I completely understand the east flow issues vs west flow issues however, the quoted comment was for the mentioning of Hawthorne and Santa Monica with relation to ZLA.
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PHLapproach
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 7:26 pm

Quoting LAXintl (Reply 1):
LA Center will try to keep LAX on west traffic until the wind component starts impacting performance of departures

It wouldn't be ZLAs call on what flow LAX would wind up running. The call comes strictly from most likely a joint decision between the ATCT Supe and the SCT Ops/Duty Mgr.
 
Cubsrule
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 8:04 pm

Does east flow versus west flow affect ground congestion/taxi times any? On the north side, it seems like taxi times for departures go up quite a bit (Terminal 1/2/3 to 24L is a very quick taxi - there are few airports that have anything like taxiiing up D8 or D7 for 24L), but the other distances seem about the same.
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uclax
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 8:11 pm

This is just an observation, but it seems like Santa Ana winds don't drive LAX to the east as often as early winter storms do, but the winds seem stronger from the east with Santa Anas. It seems like SMO changes operations to the northeast with Santa Anas much more often. Is there something about winds at higher altitudes that drives the decision?
Thanks!
...those who wait for the Lord�s help...rise up as if they had eagles� wings Isaiah 40:31
 
goboeing
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 11:16 pm

Quoting Cubsrule (Reply 7):
Does east flow versus west flow affect ground congestion/taxi times any? On the north side, it seems like taxi times for departures go up quite a bit (Terminal 1/2/3 to 24L is a very quick taxi - there are few airports that have anything like taxiiing up D8 or D7 for 24L), but the other distances seem about the same.

Maybe slightly for departure, I'm not sure, but one thing I'd like to know is, what's the usual taxi-in for A-380s when landing west?

Because Qantas 11 landed a few after us on 7R and then taxiied westbound on 7L down the runway to get to the gate! This shutdown departures for about 3-5 minutes. I had no idea they had to do this at LAX.
 
Fabo
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RE: Easterly Ops At LAX

Sat Nov 12, 2011 11:23 pm

uclax: I am not familiar with LA geography, but could it be that while both Santa Ana and storm winds are percieved as "easterly" but in fact, Santa Ana winds, being maybe just a bit more off the runway heading, would have lower tail/head component compared to storm winds?
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LAXintl
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RE: Easterly Ops At LAX

Sun Nov 13, 2011 1:01 am

Quoting PHLapproach (Reply 6):
It wouldn't be ZLAs call on what flow LAX would wind up running. The call comes strictly from most likely a joint decision between the ATCT Supe and the SCT Ops/Duty Mgr.

Correct, its actually the tower that makes the call if enough operators are having issues with wind components.

However does not change the fact that ZLA and all ATC services down the line have a strong preference to remain west ops as much as possible at LAX. Going East creates a host of logistical issues across the basin and on the conference calls its often repeated to hang in with west ops as long as possible and switch back at the soonest opportunity.
LAX will remain west-ops and occasionally even allow a few east heavy longhaul departures if it can keep from flipping the airport entirely.

Quoting Cubsrule (Reply 7):
Does east flow versus west flow affect ground congestion/taxi times any? On the north side, it seems like taxi times for departures go up quite a bit (Terminal 1/2/3 to 24L is a very quick taxi - there are few airports that have anything like taxiiing up D8 or D7 for 24L), but the other distances seem about the same.

Yes it does. But its a bit dependent on operators. As an example T-1 carriers instead of essentially being right at the takeoff threshold of 24L/R, must now taxi for a bit. Off course this could be beneficial if arriving on 06L/R as they would essentially be abeam their terminal when rolling off the runway.

Quoting uclax (Reply 8):
This is just an observation, but it seems like Santa Ana winds don't drive LAX to the east as often as early winter storms do, but the winds seem stronger from the east with Santa Anas. It seems like SMO changes operations to the northeast with Santa Anas much more often. Is there something about winds at higher altitudes that drives the decision?

Its not winds at altitude that matter. Its the surface winds.

One thing to note about Santa Ana's often produce cross winds from the North at LAX as they come off the Mojave desert basin through Santa Clarita and not the tail wind issues as do many Pacific storms.
So flipping the airport would not really alleviate a cross wind issue.

Maybe the below diagram helps better explain how Santa Ana's (high pressure compression) flow across Southern California.

From the desert to the sea, to all of Southern California
 
uclax
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RE: Easterly Ops At LAX

Mon Nov 14, 2011 3:38 am

Thanks for clarifying! Hailing from Ventura County before living in L.A., I've always thought of Santa Anas as easterly. I had never noticed that they're more from the north at LAX.
...those who wait for the Lord�s help...rise up as if they had eagles� wings Isaiah 40:31

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