SE Winds = interesting approaches


#1

Growing up in the San Francisco Bay Area, I’m fairly used to seeing the planes approach and depart from certain general directions on most days.

Today was somewhat unusual, but not unheard of. Mild, humid air, chances of rain but none really ever fell, cloud ceilings at 10,000’ish feet, and wind out of S to SE.

Typically don’t see planes come straight in from east to west over the East Bay hills on approaches to KOAK and KSFO, but they were doing it through most of the evening.

Good opportunity to run in the house, grab the binoculars, and check out the view between innings of the baseball game. At my place in the East Bay, saw several SWA’s making their approach, and even some UPS and FedEx tri-motors. I presumed those were DC-10’s, but checking Flight Aware, the UPS was actually an MD-11. Not too good at telling the two apart 6k high, and 3 miles laterally, but what a site to see when I usually only see the departures at 12k from my location.

The wind should come from the SE more often… makes plane spotting much more interesting.


#2

Ahh… you saw them flip the boat.

Looking at the METARs over the day, looks like the winds were definitely out of the south/southwest (at one point they were 200 @18G30). This puts them in their east ops flow, where they’d land on the 19s, and depart the 10s.

Generally they won’t change out of their normal configuration until the tailwind component exceeds 10kts or the crosswind component exceeds 20kts. In this case, both occurred for at least one hour (per the METAR). So they were probably in the 19/10 configuration the bulk of the day. When it dropped below that threshold (like now), they go back to normal ops (land 28s, depart 1s/28s).

Makes for an interesting flow, because the rest of the bay operates off of how SFO is set up.

BL.


#3

Ahh, thanks for confirming that. I had a feeling it had to do with something. I mean, its not the first time the wind has ever blown out of a direction other than W or NW, but the key is how hard + the crosswind component. I never knew that before.

I also didn’t know that KSFO sets the rules for KOAK (and I presume KSJC) to also follow. But it makes sense. Watching the planes from Oakland at about 10pm last night, it would have been quite dangerous to have the OAK planes taking off on runway 29 (toward the Bay Bridge), while the SFO planes were landing on runways 19L 19R. In fact, it probably would have put them in each other’s way.

At SFO, I don’t think the 19’s are quite as long as the 28’s. I wonder if that makes some pilots a little nervous about landing on them instead?


#4

Not that they really set the rules, but that how SFO is set up dictates the traffic flow for the Bay area. When you think about it, with SFO, OAK, HWD, SQL, PAO, and SJC all having near parallel runways (give/take 2 degrees) and in close proximity of eachother, aircraft into and out of those fields are all going to be parallel to eachother. So they would all have to reflect the same configuration as the major airport there (SJC and PAO might be the exception, winds permitting). If they were further away, say like the distance between LAX and ONT, and winds were different, they could have different configs in use.

At SFO, I don’t think the 19’s are quite as long as the 28’s. I wonder if that makes some pilots a little nervous about landing on them instead?

Nah… they are longer than a mile, so most should be okay If worse came to worse, 19L has the ILS, just in case. Also, with this config, just because they would be departing the 10s, wouldn’t mean that they also couldn’t have an aircraft land on the 10s. When winds get hard enough, they’ll go to a straight 10 setup, where they’ll land and depart 10L/R.

BL.


#5

In southern California, local airports have separate procedures for when LAX is east traffic. IFR routings change, different approach control procedures, stuff like that. But that doesn’t mean that all the local airports have to be east traffic just because LAX is…Long Beach, for example, can be west traffic when LAX is east, etc.

So, I’m curious: are the local SFO area airports required to go east traffic just because SFO is east?


#6

From what I’ve gathered, the proximity of them all really does require them to fall in line with one another. It’s something I had never really thought about before, but it does make sense.

I think the airports are more spread apart in L.A.


#7

True, but the big difference for LAX and LGB is the crossing restriction for the arrivals from northwest. The TANDY3 arrival from the NW has a crossing restriction 14nm west of LAX at 14000, which if LAX were east, the arrivals turning final would be about 10000ft below that restriction. So the arrivals are separated there. With the departures, they would join the departure stream at SLI for going over the Coachella valley, or north towards Vegas, which blends in with the LAX east ops stream.

So, I’m curious: are the local SFO area airports required to go east traffic just because SFO is east?

Pretty much.

Think about it this way. Under normal ops, SFO lands on 28L/R, and depending on aircraft type, departs either 28L/R or 1L/R.

OAK, on the other hand lands and departs 28L/R and 29 under normal ops. If OAK were to flip the boat and land the 10s and 9 while SFO is under normal ops, the 1L/R departures would run T-bone into the arrivals for 9 and 10L/R.

Then there is this. ONT is approx. 42nm from LAX. SQL, HWD, and OAK are less than 15nm. So SFO’s arrival flow would greatly influence their streams. MUO, PAO, and SJC might be able to get away with running their own configs, but their departure flow runs right into the CVFP, VOR, and ILS approach paths for SFO, so it’s a tossup.

BL.