Some major international airports seem to only have runways for average prevailing wind conditions. Why do they not have a crosswind runway for special circumstances? Do these airports not experience extreme crosswind conditions at times? And what do airlines do in extreme crosswind conditions at these fields? Is it not cost effective for the airports to build crosswind runways for these exceptional conditions?

IDK but I would assume that LAX mostly have winds from the west due to the ocean (sea breeze) and the general climate. But also if you look at
the geography at LAX you will see that there are mountains just to the north of the airport and possibly they are high enough to
make a crosswind runway unsuitable?

Prevailing winds. LAX nearly never gets winds that aren't either coming from the West (95%+) or Santa Ana winds from East, or within 30 degrees of such. Further, the airport doesn't have the geographic space to put one in. Same with PHX.

Thunderboltdrgn wrote:

IDK but I would assume that LAX mostly have winds from the west due to the ocean (sea breeze) and the general climate. But also if you look at
the geography at LAX you will see that there are mountains just to the north of the airport and possibly they are high enough to
make a crosswind runway unsuitable?

KSMO's runway is mostly North/South (3/21), and it is closer to those same mountains. Not an issue.

LAX used to have a crosswind runway 16-34 before the airfield was expanded to 3 parallel runways...and eventually four:

viewtopic.php?f=3&t=1464235

Back in the day, with pistons, crosswinds were more limiting. We can land up to a forty knot crosswind.

That's quite a bit of wind before you need a different runway direction. Having only parallel runways simplifies things significantly, which is why almost all large airports built in recent decades have only parallel runways.

convair880mfan wrote:

Some major international airports seem to only have runways for average prevailing wind conditions. Why do they not have a crosswind runway for special circumstances? Do these airports not experience extreme crosswind conditions at times? And what do airlines do in extreme crosswind conditions at these fields? Is it not cost effective for the airports to build crosswind runways for these exceptional conditions?

I think you answered your own question. Exceptional conditions don't warrant spending the billions on a crosswind runway that would waste space the other 99% of the time. Several fields used to have crosswind runways, then yanked them in favor of a parallel setup. LHR and ORD come to mind, I'm sure there's more.

LH707330 wrote:

convair880mfan wrote:

Some major international airports seem to only have runways for average prevailing wind conditions. Why do they not have a crosswind runway for special circumstances? Do these airports not experience extreme crosswind conditions at times? And what do airlines do in extreme crosswind conditions at these fields? Is it not cost effective for the airports to build crosswind runways for these exceptional conditions?

I think you answered your own question. Exceptional conditions don't warrant spending the billions on a crosswind runway that would waste space the other 99% of the time. Several fields used to have crosswind runways, then yanked them in favor of a parallel setup. LHR and ORD come to mind, I'm sure there's more.

ORD does still have crosswind runways, which are used reasonably often. LHR's crosswind runway was always too short for use in with heavy aircraft.

Starlionblue wrote:

Back in the day, with pistons, crosswinds were more limiting. We can land up to a forty knot crosswind.

That's quite a bit of wind before you need a different runway direction. Having only parallel runways simplifies things significantly, which is why almost all large airports built in recent decades have only parallel runways.

This one is your best explanation - majority of large transport aircraft today can cope with a higher crosswinds better than 1930's and 1940's technology, which was prevailing at times old airports were built using multiple runways in various directions. O'Hare's original seven runways enabled traffic to use optimal heading for takeoff given variable wind conditions.

Throw in noise abatement and the need to limit the footprint an airport has on metro areas plus a higher traffic throughput without crossing traffic patterns it is the preferred set-up when new airports were build in more recent decades and existing ones closed runways no longer needed.

N1120A wrote:

LH707330 wrote:

convair880mfan wrote:

Some major international airports seem to only have runways for average prevailing wind conditions. Why do they not have a crosswind runway for special circumstances? Do these airports not experience extreme crosswind conditions at times? And what do airlines do in extreme crosswind conditions at these fields? Is it not cost effective for the airports to build crosswind runways for these exceptional conditions?

I think you answered your own question. Exceptional conditions don't warrant spending the billions on a crosswind runway that would waste space the other 99% of the time. Several fields used to have crosswind runways, then yanked them in favor of a parallel setup. LHR and ORD come to mind, I'm sure there's more.

ORD does still have crosswind runways, which are used reasonably often. LHR's crosswind runway was always too short for use in with heavy aircraft.

But when conditions require use of the two remaining crosswind runways, the arrival rate at ORD is slashed. IIRC, nearly every winter storms includes strong winds from the north.

Crosswind runways are still quite important in the Northeast US. BOS, JFK and LGA all regularly use their crosswind runways. Newark uses theirs some, though they try and limit it.

FlyHossD wrote:

N1120A wrote:

LH707330 wrote:

I think you answered your own question. Exceptional conditions don't warrant spending the billions on a crosswind runway that would waste space the other 99% of the time. Several fields used to have crosswind runways, then yanked them in favor of a parallel setup. LHR and ORD come to mind, I'm sure there's more.

ORD does still have crosswind runways, which are used reasonably often. LHR's crosswind runway was always too short for use in with heavy aircraft.

But when conditions require use of the two remaining crosswind runways, the arrival rate at ORD is slashed. IIRC, nearly every winter storms includes strong winds from the north.

That may be true, but they do still have and use them with regularity. They are also decent at getting as much use as possible from them and from the other runways for departures in order to allow for higher rates than would otherwise be possible.

N1120A wrote:

Crosswind runways are still quite important in the Northeast US. BOS, JFK and LGA all regularly use their crosswind runways. Newark uses theirs some, though they try and limit it.

FlyHossD wrote:

N1120A wrote:

ORD does still have crosswind runways, which are used reasonably often. LHR's crosswind runway was always too short for use in with heavy aircraft.

But when conditions require use of the two remaining crosswind runways, the arrival rate at ORD is slashed. IIRC, nearly every winter storms includes strong winds from the north.

That may be true, but they do still have and use them with regularity. They are also decent at getting as much use as possible from them and from the other runways for departures in order to allow for higher rates than would otherwise be possible.

I suppose in some places winds vary significantly enough to make crosswind runways a must-have.

The question is if BOS, JFK and LGA were built today, would they feature crossing or only parallel runways?

Starlionblue wrote:

N1120A wrote:

Crosswind runways are still quite important in the Northeast US. BOS, JFK and LGA all regularly use their crosswind runways. Newark uses theirs some, though they try and limit it.

FlyHossD wrote:

But when conditions require use of the two remaining crosswind runways, the arrival rate at ORD is slashed. IIRC, nearly every winter storms includes strong winds from the north.

That may be true, but they do still have and use them with regularity. They are also decent at getting as much use as possible from them and from the other runways for departures in order to allow for higher rates than would otherwise be possible.

I suppose in some places winds vary significantly enough to make crosswind runways a must-have.

The question is if BOS, JFK and LGA were built today, would they feature crossing or only parallel runways?

Probably not, unless they were located in different places. All 3 have ocean on multiple sides, which results in much more variable weather than if there is no ocean or you only have ocean on one side.

Remember that DEN was built with crosswind runways, and it is one of the newest major airports in the world. DFW is another jet era airport that was built with crosswind runways.

ZRH is another place where the crosswind runways are used a lot - often at the same time.

N1120A wrote:

Remember that DEN was built with crosswind runways, and it is one of the newest major airports in the world. DFW is another jet era airport that was built with crosswind runways.

DFW is very much like ORD in that respect, however. The 31s are rarely used and when they are, traffic capacity is greatly diminished.

I beleive if they if they had anticipated those things more accurately, they may well have fore went their construction.

DarkSnowyNight wrote:

N1120A wrote:

Remember that DEN was built with crosswind runways, and it is one of the newest major airports in the world. DFW is another jet era airport that was built with crosswind runways.

DFW is very much like ORD in that respect, however. The 31s are rarely used and when they are, traffic capacity is greatly diminished.

I beleive if they if they had anticipated those things more accurately, they may well have fore went their construction.

The interesting thing about DFW is that it appears they initially left themselves some room for additional crosswind runways, and spaced the highways out to do so. There's definitely enough room between 31L and SR 360, but there are warehouses and a couple apartment complexes that have been built on the site. There's a smaller amount of space north of 31R, but it's almost all developed, with what looks to be some fairly expensive housing that's been built between the airport and SR 114.

GSOtoIND, the original DFW masterplan does not call for additional crosswind runways.

What the plan does provide for is an additional north/south runway (a sixth N/S runway) on the west side of the airfield (beyond the West Air Freight and West Hangar complexes) that would actually cross (intersect) with Runway 13R/31L.

e38

Just down the the road from DFW, DAL no longer has a crosswind runway.

MEM is another airport that uses its crosswind runway all the time - in fact, the crosswind runway gets more use than the other 3. Of course, that is because it is right next to the FedEx hub and used primarily for their flights, but still.

GSOtoIND wrote:

DarkSnowyNight wrote:

N1120A wrote:

Remember that DEN was built with crosswind runways, and it is one of the newest major airports in the world. DFW is another jet era airport that was built with crosswind runways.

DFW is very much like ORD in that respect, however. The 31s are rarely used and when they are, traffic capacity is greatly diminished.

I beleive if they if they had anticipated those things more accurately, they may well have fore went their construction.

The interesting thing about DFW is that it appears they initially left themselves some room for additional crosswind runways, and spaced the highways out to do so. There's definitely enough room between 31L and SR 360, but there are warehouses and a couple apartment complexes that have been built on the site. There's a smaller amount of space north of 31R, but it's almost all developed, with what looks to be some fairly expensive housing that's been built between the airport and SR 114.

It does look like they still could do that if they were willing to offset a little to the SW, starting just south of CAE Sims by the 36s... Neat.

But I agree with other posters that it probably will not happen, and with what you say with other areas having been developed for other things, it is probably a matter of time for that to happen there too. I have not been there in about three years, but that seems to jive with the memory.
I get that that other things are probably a better use of the space, but I have to say that on days when they actually need to use 31L, things pretty much come to a standstill. Unsurprising, as with only 31L/R, we have two Rwys doing the job of six for landings. . .

dfwjim1 wrote:

Just down the the road from DFW, DAL no longer has a crosswind runway.

That Rwy was really only good for GA though IIRC, and when they eventually decided it was too close to local housing, its closure was not surprising. I also do not recall a lot of usage when it was operational though. Also, I did not realize that it was just only closed in 2017. For some reason —maybe the low usage— I thought it was closed at least a few years prior.

N1120A wrote:

ZRH is another place where the crosswind runways are used a lot - often at the same time.

In that case, though, it's rarely due to weather constraints and more because ZRH simply doesn't have parallel runways. Noise constraints also play a role.

FRA has runway 18, which is often used for take-offs. But that wasn't designed as a crosswind runway, it simply wasn't possible to easily construct another parallel runway at the time.

HAM has two intersecting runways, which are often simultaneously in use (if winds permit). Being relatively close to the north sea, it can experience strong crosswinds. AMS and CPH are similar, though CPH has considered removing the crosswind runway to make room for more terminals.

convair880mfan wrote:

Some major international airports seem to only have runways for average prevailing wind conditions. Why do they not have a crosswind runway for special circumstances? Do these airports not experience extreme crosswind conditions at times? And what do airlines do in extreme crosswind conditions at these fields? Is it not cost effective for the airports to build crosswind runways for these exceptional conditions?

You may find the link posted here interesting. It's a compilation of wind observations (in this case, from 1970 to Feb. 2021) that provides a database of historic wind coverage at LAX. The first graph comprises the average of the total recorded observations during the period. Scroll down for the typical month-by-month wind coverage.

Notice that LAX has relatively few northerly (or southerly, for that matter) wind events as a total of all wind events. When those occur - such a with our mid- and late-Fall off shore wind events, or with the passage of early winter frontal systems moving from northwest to southeast - they tend to be brief in duration. Further, because of geography, LAX (really, most of coastal California) lacks the true, prolonged seasonal shifts of wind that typically occur at interior points of the country (certainly beyond the Pacific coastal zone).

https://mesonet.agron.iastate.edu/sites ... rk=CA_ASOS

Here is the link for the historical PHX wind coverage. A greater east-west orientation, on average, than LAX:
https://mesonet.agron.iastate.edu/sites ... rk=AZ_ASOS

Wonderful, wonderful information. Thanks so much.

Just an FIY, ORD is strictly on the 4's right now, so only the 2 crosswind runways on the field in use, due to strong winds out of the northeast:

KORD 251458Z 04024G36KT 6SM -RA BR FEW013 BKN018 OVC030 10/08 A2978 RMK AO2 PK WND 04036/1452 P0000 T01000083 $

A ground delay program approaching 3 hours and climbing is in effect. Going to be a nasty day.