lookin' to be east ops

[Keith Smith]

It's been east ops for the whole afternoon, should make for an interesting night if the weather holds. Tonight is the western region night, spotlight on ZSE. I assume we'll get some traffic from that.

Look sharp, Approach and Tower, get ready to ammend some routes ;)

[bradl]

This may be a question for IM to answer, but I'll ask it here anyway.

when it comes to SFO, I've looked at the METAR and called the ATIS number to see what has been going on there in terms of runways in use, and it seems to me that they will only drop down to 2 runways in use when winds exceed 25kts in a given direction (which winds are currently 190/16G25). SFO is currently landing/departing 19L/R (10s are not in use, even though they are 90 degrees left crosswind from runway heading). Is this SOP? I know when winds exceed 10, they will land 19, and depart 10 (all 4 in use). This isn't the case.

Could anyone get any clarity on this, or would this involve a call to the tower?

BL.

[Stephen Zedalis]

Hmm, given the winds you mention I would be using the 19s as well and avoid the 10s due to crosswinds, especially if traffic could be accomodated on two parallel runways. Its a close call since the gusts aren't "too" bad. Its not so much being over 10 kts, but the gusting component that makes things interesting.

Also take a look at our current SOP 050 and pay particular attention to the new section 4a. It appears that the RW runway assignment is exactly per ZOA SOP. Ie. In east ops you use 19L/R for landing, for departures you can use all 4, but then if you have a wind angle >30 degrees and wind >20 kts then that runway is closed for departures. I would call 16G25 close enuf to >20 kts.

[Inigo Markle-Allen]

Hey Brad,

I wish I had the actual numbers for you, but I agree. From experience I've learned that SFO drops down to two runway ops after the wind hits 20-25 kts. Still, I've heard 28 arrivals landing in winds gusting up to 40, so I'd say that shutting down runways for a 30 degree crosswind component is a little bit too overcautious. If that were the case, you'd see a lot more "Circle to land 1L/R" visual approaches, which only happen once or twice a year, if that (conditions have to be wind out of the NE at greater than, I'm tryin to remember I wanna say 25 kts). What you're talking about is just a reverse situation of that - Winds out of the SW at up to 25 kts, perfect for rwy 19 departures but a 90 degree angle to departures from rwys 10. Basically... I think your 25 knot guess is right on, but as per the SOP, I'm not positive SFO would shut down two runways - limiting its capacity by 1/2 - simply because of a mere 30 degree crosswind, so I'm thinking the number's got to be higher than that, and I wouldn't fully trust the SOP to fully reflect SFO's real world ops.

[Dan Sprouse]

Currntly the SOP is set to state that a runway will be shutdown for departures if the winds are at 30 deg to the runway or more and at or above 20 knots. In the case listed the winds are at 16 knots and have some gust this is not the same as having 20 knot winds.

In order to shut down a runway the winds must be at a constant 20knot or above state. Oherwise we could say shut the runways down when we have Gust above 20knots.

And these are some numbers that we chose to try they are not Gods law if we see that the winds do exceed these by a weekly basis then they can be changed. But so far I have not seen the need to close the Runways.

[nobody291]

I would suggest that the wording be changed to a crosswind component of 20 knots, rather than 20 knot wind speed at greater than 30 degrees. By the letter of the SOP (I know this is not the intent, but it is merely the letter), if the wind were 240 @ 25 all runways would be closed to departures. Perhaps change the wording to: "avoid assigning departure runways on which the crosswind component would exceed 20 knots?"

[Inigo Markle-Allen]

Eric,

Precisely what I was thinking (but I've done enough SOP critiquing to last me a while :P). There certainly are instances at SFO when the wind direction is such that wind speed can be in excess of 20 knots with all four runways still in use. "If possible, avoid assiging runways in which the crosswind component would exceed 20 knots" would cover everything. In east ops, there can be pretty hefty crosswinds from the SE/SW which the crosswind component can exceed 20 knots, but because of the low visibility and cloud cover often associated with SFO east ops, the ILS 19L is the only available approach (as opposed to a visual to 10L/R which I hear happen once in a blue moon). That wording would cover everything and still allow for real world exceptions like I've mentioned above.

[Keith Smith]

Not to complicate matters, but is everyone comfortable calculating xwind components?

To do it right, it would be SIN( wind direction - 10 - rwy hdg) * wind strength.

If you want a rule of thumb, if the wind direction - 10 - rwy hdg < 30, the component will be less than half of the wind strength.

If it&#39;s more than 30 degrees, it&#39;ll be more than half the wind strength, if that helps.

[feathers]

Originally posted by keith@Mar 27 2004, 07:40 AM
Not to complicate matters, but is everyone comfortable calculating xwind components?

To do it right, it would be SIN( wind direction - 10 - rwy hdg) * wind strength.

If you want a rule of thumb, if the wind direction - 10 - rwy hdg < 30, the component will be less than half of the wind strength.

If it&#39;s more than 30 degrees, it&#39;ll be more than half the wind strength, if that helps.
Oh come on with the complicated math&#33; All we have to do is break out our E6Bs and check the crosswind component table, right?

I mean, we all do have an E6B...? ^_~

P.S. I saw you try to sneak in that little -10 in there to turn it into mag heading. ^_^