mjsmigel
Posts: 57
Joined: Thu Oct 31, 2002 4:57 am

Flight Paths Into SFO Thru Nevada

Thu Nov 21, 2002 4:48 am

How come most of the flights originating from the southern U.S. going into San Francisco always take that northerly route (i.e. roughly Trinidad, Colorado to Reno, Nevada)? I see DFW-SFO flights do this all the time and this seems awfully far north.

It seems there is much shorter distance and less fuel burn routing via Las Vegas NV rather than going north of the Nellis Test Range.

MJ

 
Guest

RE: Flight Paths Into SFO Thru Nevada

Thu Nov 21, 2002 4:55 am

Well just on a hunch, I suspect that it could be to avoid conflict with all of the transcon traffic (EWR, PHL, JFK, etc) heading in and out of Southern California. Most of that traffic comes and goes via LAS.

Then there's always the nonexistant Area 51.
 
OPNLguy
Posts: 11191
Joined: Tue Jun 15, 1999 11:29 am

RE: Flight Paths Into SFO Thru Nevada

Thu Nov 21, 2002 5:52 am

I made a map with Great Circle routes from a few major US terminals into SFO. Please refer to:

http://gc.kls2.com/cgi-bin/gc?PATH=MIA-SFO%2C+ATL-SFO%2C+IAD-SFO%2C+JFK-SFO%2C+ORD-SFO%2C+MSP-SFO%2C+DEN-SFO%2C+IAH-SFO%2C+DFW-SFO%2C+PHX-SFO&RANGE=&PATH-COLOR=&PATH-UNITS=mi&SPEED-GROUND=&SPEED-UNITS=kts&RANGE-STYLE=best&RANGE-COLOR=&MAP-STYLE=

As you can see, pretty much anything inbound to SFO from south of ATL (MIA, DFW, IAH, and PHX, in the example) have shorest distances that take them over LAS. Other stuff from points north of ATL (IAD, JFK, ORD and MSP, in the example) takes them well north of LAS, and south of RNO.

All that said/shown, the shortest distances aren't always the ones flown, obviously. ATC has a big hand in this, as was alluded to, as they try to design the traffic flows so as to avoid saturating individual ARTCC sectors with too much traffic. ATC published the resultant "Preferred Routes" between many major terminals, and that's what they expect the users (airlines) to plan and file.

The "Pref" routes sometimes get changed. For years, PHX-SFO flights went up over LAS/BLD, and then up to BTY (Beatty) and up J92, and then westbound, comming into the Bay area over MODesto. Then, it changed. The stuff now heads west of PHX to PMD (Palmdale, CA) and then turns northward from there. Notice on the map that the GC distance PHX-SFO falls right inbetween these routings, so a fuel penalty is paid either way.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
Tom in NO
Posts: 6725
Joined: Thu Nov 11, 1999 10:10 am

RE: Flight Paths Into SFO Thru Nevada

Thu Nov 21, 2002 6:14 am

I've flown MSY-SFO on UA a couple of times. The routing we took was over the Farmington, NM VOR, then as I recall, we flew to the Coaldale, NV VOR. The Nellis range is very active, and the flight restrictions are usually kept in place. I remember on one of the flights hearing (on Channel 9) the pilot ask if we could "cut the corner". Of course, the request was denied.

You'll have to excuse me as my High Altitude En-Route charts are at home. Those have the victor airways, and the VOR's involved, but Farmington and Coaldale are the two that stick out in my mind the most. The Coaldale VOR is closer to the northwest corner of the restricted area, there is a VOR towards the northeast corner, as well. It might be Wilson Creek, but I'm not 100% sure.

I'll do a little digging on the Internet, and see if I can come up with some more info (won't be home for another 7 hours).

I'd agree with the ARTCC saturation comments, adding that there's probably less (by how much is anybody's guess, especially with SJC and OAK in the mix) traffic going the northern route into SFO than inbounds into the LAX basin. Plus there's all that eastbound climbing traffic out of LAX, SAN, ONT, etc.

Tom in NO (at MSY)
"The criminal ineptitude makes you furious"-Bruce Springsteen, after seeing firsthand the damage from Hurricane Katrina
 
Tom in NO
Posts: 6725
Joined: Thu Nov 11, 1999 10:10 am

RE: Flight Paths Into SFO Thru Nevada

Thu Nov 21, 2002 6:50 am

I mixed up my VOR's. The one closest to the northwest corner of the Nellis restricted area is Tonopah. Coaldale VOR is a little bit west of Tonopah, and is an entry VOR for one of the STAR approaches into SFO.

Tom in NO (at MSY)
"The criminal ineptitude makes you furious"-Bruce Springsteen, after seeing firsthand the damage from Hurricane Katrina
 
Guest

RE: Flight Paths Into SFO Thru Nevada

Thu Nov 21, 2002 8:28 am

There is a lot of restricted military airspace over south central Nevada (Area 51) and over California NW of LAS. Most of the time you cannot fly direct from LAS to SFO. Most times I fly, we fly north out of LAS to the are of Mono Lake before heading west towards SFO. On the SFO-LAS flights we normally cut accross the Sierra's from Clovis VOR (Fresno area) and then head south once on the backside of the Sierra's to avoid the military airspace. Occasionaly when this airspace is not active, commercial airline flights are allowed through. One time I was flying United from SFO-LAS and was listening in on Channel 9 and the pilots were handed off to military controllers at Joshua Control while we were in their airspace.
 
Tom in NO
Posts: 6725
Joined: Thu Nov 11, 1999 10:10 am

RE: Flight Paths Into SFO Thru Nevada

Fri Nov 22, 2002 1:13 am

OK guys, it's a relatively slow day to begin with, so I brought my handy-dandy, albeit a little bit dated High Altitude Enroute chart to work. Since DFW-SFO was mentioned above, I'll run mileage totals on both the southern and northern jet routes arounds the MOA's.

Southern: DFW-SPS-TXO (J72), TXO-CNX-SJN (J74), SJN-DRK (J231), DRK-EED-PMD-AVE (J6), AVE-OAK (closest VOR) (J1).....the mileage is 1,354 nm.

Northern: DFW-SPS-TCC-LVS (J76), LVS-FMN-MLF-ILC-OAL-ECA-OAK (J58).....the mileage is 1,293 nm. This routing goes a little out of the way from FMN-OAL, if we corner-cut a little, it knocks 13 miles off the routing.

Uh oh, guys, it seems that flying the northern route is actually a little bit shorter (by 57 nm). Two things I didn't take into account while crunching these numbers:
1) the Instrument Approach Procedures routings into SFO (probably some miles added on both routings, but not a bunch); nor SID's from DFW (both to SPS, so no difference)
2) direct routings from ARTCC (though probably not as possible closer to the MOA's).

Tom in NO (at MSY)
"The criminal ineptitude makes you furious"-Bruce Springsteen, after seeing firsthand the damage from Hurricane Katrina

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