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 Crosswind Runway In Relation To Primary Runway
 naruto38700 From Singapore, joined Dec 2012, 7 posts, RR: 0Posted Sat Dec 29 2012 07:36:26 UTC (3 years 4 months 4 weeks 1 day 11 hours ago) and read 7808 times:

 Hi everyone, this is about the project I am doing now. We are asked to design an airport with relevant details on the runways. So here is my question, I wonder if crosswind runways are always perpendicular to the primary runway, or are they just oriented to the prevailing crosswind? One more thing, according to the question paper, only one runway is needed to satisfy current traffic demand. However, prevailing wind is at 050° while Crosswind is at 120°, so is it safe for me to assume that a crosswind runway will be needed? Thanks!
 vikkyvik From United States of America, joined Jul 2003, 12136 posts, RR: 24 Reply 1, posted Sat Dec 29 2012 08:27:14 UTC (3 years 4 months 4 weeks 1 day 10 hours ago) and read 7778 times:

 Quoting naruto38700 (Thread starter): So here is my question, I wonder if crosswind runways are always perpendicular to the primary runway, or are they just oriented to the prevailing crosswind?

My suggestion would be to go look at airport diagrams. Many US ones are available here:

www.airnav.com

You'll find that runways have all sorts of orientations, and most of them aren't exactly perpendicular.

 Quoting naruto38700 (Thread starter):However, prevailing wind is at 050° while Crosswind is at 120°, so is it safe for me to assume that a crosswind runway will be needed?

That's not enough information to make that determination. If the crosswind only gets up to, say 2 or 3 knots, then I'd say no, you don't need it. But there are more factors that would have to be considered.

 I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 tdscanuck From Canada, joined Jan 2006, 12710 posts, RR: 78 Reply 2, posted Sat Dec 29 2012 10:30:02 UTC (3 years 4 months 4 weeks 1 day 8 hours ago) and read 7741 times:

 Quoting naruto38700 (Thread starter):So here is my question, I wonder if crosswind runways are always perpendicular to the primary runway, or are they just oriented to the prevailing crosswind?

Exactly perpendicular is relatively rare. If you're going to go to all the trouble to make a crosswind runway, you might as well align to the prevailing crosswind. Especially since exactly perpendicular takes up the most space so you only want to do it if you really have to.

 Quoting naruto38700 (Thread starter):However, prevailing wind is at 050° while Crosswind is at 120°, so is it safe for me to assume that a crosswind runway will be needed?

As noted, it's going to depend a lot on the wind. But also on other weather factors (do you have enough capacity on your single even if the weather is bad? could you do simultaneous operations on the crossed runways?). And what shape is your land plot? Who's under the approach and departure ends of each runway? This all factors in.

Tom.

 Mir From United States of America, joined Jan 2004, 22864 posts, RR: 53 Reply 3, posted Sat Dec 29 2012 12:25:54 UTC (3 years 4 months 4 weeks 1 day 6 hours ago) and read 7714 times:

 Quoting naruto38700 (Thread starter):So here is my question, I wonder if crosswind runways are always perpendicular to the primary runway, or are they just oriented to the prevailing crosswind?

It really depends. Normally, you would have it aligned with the prevailing crosswind to the extent practical. But if you're going to start talking about using it not only as a crosswind runway but as a second usable runway (i.e. have two runways going at the same time to improve traffic flow), then a perpendicular runway has some advantages.

-Mir

 7 billion, one nation, imagination...it's a beautiful day
 rfields5421 From United States of America, joined Jul 2007, 7885 posts, RR: 32 Reply 4, posted Sat Dec 29 2012 14:40:49 UTC (3 years 4 months 4 weeks 1 day 4 hours ago) and read 7665 times:

A great many runways / airports around the world have runways based on the early history. The runways at Heathrow evolved from three runway pairs to the current two runways.

Chicago's O'Hare was a mess of runways for different wind conditions - slowly being converted to a predominant wind direction runway setup.

Airports like JFK, LGA, EWR, PHL all have physical geography constraints which limited the way the runways could be built. SAN is an example of successfully combining wind direction and physical geography to allow a busy airport to operate near the city center. It just has absolutely no possibility of growth, or alternate operation if winds are bad.

 Quoting tdscanuck (Reply 2):Exactly perpendicular is relatively rare.

True, but back before WWII - perpendicular runways seemed to be a preference which make it common at many of the older airports - i.e. SFO, JFK, LGA, PHL.

The Army Air Corps built many training bases across the US, which the USAF later upgraded to jet bases with perpendicular runways, and 45 degree cross runways. Seemed to be a standard pattern many places, despite normal wind speeds and directions.

Perhaps a good example of modern wind directed airport design (even though the design is 50 years old) is DFW with a primary wind direction 5 runways, and an alternate pair usable most of the time, and occasionally the only usable runways in wind conditions like we had a couple weeks ago.

Or DEN - where the wind change possibilities must be extreme with four north/south runways and two east/west runways.

 Starlionblue From Greenland, joined Feb 2004, 17654 posts, RR: 65 Reply 5, posted Sat Dec 29 2012 17:40:52 UTC (3 years 4 months 4 weeks 1 day 1 hour ago) and read 7615 times:

 Another issue is the type of traffic. Modern airliners can handle way more crosswind than smaller aircraft, particularly GA planes. Compare KMCO, which services airliners, and KISM, which services primarily GA. They are quite close to each other, so wind conditions are close to each other. KISM has two runways at 90 degrees while KMCO has parallel ones. No way a Cessna 172 can handle 20 knots crosswind, something an airliner lands in without problems. BTW for an airport with V-shaped runway layout, check out KGNV. http://155.178.201.160/d-tpp/1213/00973AD.PDF
 "There are no stupid questions, but there are a lot of inquisitive idiots."
 JoeCanuck From Canada, joined Dec 2005, 6364 posts, RR: 33 Reply 6, posted Sat Dec 29 2012 18:21:32 UTC (3 years 4 months 4 weeks 1 day ago) and read 7605 times:

 YYC has two runways crosswind to the main north/south runway. They are both significantly shorter but since they are only in to airliners during severe crosswind situations, they don't have to be as long. The crosswind runways also serve to keep smaller GA aircraft out of the landing and takeoff patterns used by the airlines. There is more than enough room for most smaller aircraft to stop short of the intersection. That being said, crosswind ops seem to be a real pain sometimes, resulting in lots of holds and delays. A larger version is available here; http://www.gcmap.com/diagrams/pdf/CYYC.pdf
 What the...?
 LU9092 From United States of America, joined Oct 2007, 129 posts, RR: 1 Reply 7, posted Sun Dec 30 2012 10:34:39 UTC (3 years 4 months 4 weeks 8 hours ago) and read 7484 times:

 Quoting rfields5421 (Reply 4):Or DEN - where the wind change possibilities must be extreme with four north/south runways and two east/west runways.

Having grown up in CO, I was somewhat surprised to learn that the prevailing wind in DEN is from the south, except for the month of April, where it is instead from the north. My impression from having lived there for nearly 30 years is that the typical case is light winds that allow any runway to be used. The most common high wind scenarios - and this is based only on my own observations - would be high, gusty downslope winds, mostly in winter and spring, and then straight line thunderstorm winds caused by downdrafts in the summer that can be from any (or all!) directions. Less common are the steady 10-15kt upslope winds from the east or southeast that tend to herald the arrival of wet, heavy snow from late winter through spring. If you notice a strong upslope from mid-July into August, keep your eye on the sky. Someone is likely to see serious flooding, as in Ft. Collins on July 26-27, 1997, or the Big Thompson River basin in 1976.

Bringing it back to perpendicular runways, DEN certainly has the space for them, and the fact that when there are crosswinds, they tend to be strong and gusty, makes that pair of east-west runways essential. I believe that DEN's master plan allows for two more parallel east-west runways and four additional north-south.

 naruto38700 From Singapore, joined Dec 2012, 7 posts, RR: 0 Reply 8, posted Sun Dec 30 2012 18:53:09 UTC (3 years 4 months 3 weeks 6 days 23 hours ago) and read 7414 times:

 Quoting vikkyvik (Reply 1):My suggestion would be to go look at airport diagrams. Many US ones are available here: www.airnav.com

Thanks for giving me this website! We are also asked to draw the layout of the airport so this will be very helpful!

So I think I will be adding a crosswind runway oriented to 120°/300° since the prevailing crosswind is at 45 knots

 DiamondFlyer From United States of America, joined Oct 2008, 2395 posts, RR: 4 Reply 9, posted Sun Dec 30 2012 19:05:14 UTC (3 years 4 months 3 weeks 6 days 23 hours ago) and read 7409 times:

 Quoting Starlionblue (Reply 5): No way a Cessna 172 can handle 20 knots crosswind, something an airliner lands in without problems.

Say what? A 172 can absolutely handle 20 knots of crosswind.

-DiamondFlyer

 Starlionblue From Greenland, joined Feb 2004, 17654 posts, RR: 65 Reply 10, posted Sun Dec 30 2012 20:19:04 UTC (3 years 4 months 3 weeks 6 days 22 hours ago) and read 7388 times:

 Quoting DiamondFlyer (Reply 9):Quoting Starlionblue (Reply 5): No way a Cessna 172 can handle 20 knots crosswind, something an airliner lands in without problems. Say what? A 172 can absolutely handle 20 knots of crosswind.

Ok fair enough but it is well beyond the demonstrated max.

 "There are no stupid questions, but there are a lot of inquisitive idiots."
 naruto38700 From Singapore, joined Dec 2012, 7 posts, RR: 0 Reply 11, posted Mon Dec 31 2012 00:20:19 UTC (3 years 4 months 3 weeks 6 days 18 hours ago) and read 7351 times:

 Quoting JoeCanuck (Reply 6):The crosswind runways also serve to keep smaller GA aircraft out of the landing and takeoff patterns used by the airlines. There is more than enough room for most smaller aircraft to stop short of the intersection.

Hi, I understand you are saying that crosswind runways serve two purposes, both for airliners to take off and land when crosswind prevails, as well as for GA aircraft to operate under normal conditions.

But in the case of YYC, would it not be a problem if GA aircraft operate on crosswind runway while airliner operate of main runway at the same time? You know, since they intersect each other, would it not reduce the efficiency of both runways?

 Starlionblue From Greenland, joined Feb 2004, 17654 posts, RR: 65 Reply 12, posted Mon Dec 31 2012 00:33:15 UTC (3 years 4 months 3 weeks 6 days 18 hours ago) and read 7348 times:

 Quoting naruto38700 (Reply 11):But in the case of YYC, would it not be a problem if GA aircraft operate on crosswind runway while airliner operate of main runway at the same time? You know, since they intersect each other, would it not reduce the efficiency of both runways?

I'll speculate that if you can get GA to use another runway you're increasing efficiency even if they intersect. Just the decrease in wake turbulence separation between airliners and smaller GA planes will save you a boatload of time.

 "There are no stupid questions, but there are a lot of inquisitive idiots."
 naruto38700 From Singapore, joined Dec 2012, 7 posts, RR: 0 Reply 13, posted Mon Dec 31 2012 10:26:41 UTC (3 years 4 months 3 weeks 6 days 8 hours ago) and read 7253 times:

 Quoting Starlionblue (Reply 12):I'll speculate that if you can get GA to use another runway you're increasing efficiency even if they intersect. Just the decrease in wake turbulence separation between airliners and smaller GA planes will save you a boatload of time.

Now that is very true! I failed to take the wake turbulence into consideration, especially since I will have A380 operating in my airport! Truly grateful for the answer, have a happy new year since we are in the same time zone :P

 JoeCanuck From Canada, joined Dec 2005, 6364 posts, RR: 33 Reply 14, posted Mon Dec 31 2012 13:53:56 UTC (3 years 4 months 3 weeks 6 days 4 hours ago) and read 7228 times:

 Quoting naruto38700 (Reply 11):But in the case of YYC, would it not be a problem if GA aircraft operate on crosswind runway while airliner operate of main runway at the same time? You know, since they intersect each other, would it not reduce the efficiency of both runways?

While ATC won't let 2 aircraft land or take off at the same time on intersecting runways, they don't need the same kind of spacing if everybody is one behind the other on the same runway.

Basically, ATC will give the planes time and space to execute a go-around in case of runway excursion. Everybody will know a crosswind runway is being used so everyone is ready to act if an incursion takes place. With proper spacing, time is allowed that even if the landing or taking off plane does cross the intersection, it will probably not be an issue. The plane just has to make it across the taxiway hashmarks to be clear of the main runway...which only takes a few seconds.

You also don't have the wake turbulence issues which are a large consideration to approach spacing.

 What the...?
 vikkyvik From United States of America, joined Jul 2003, 12136 posts, RR: 24 Reply 15, posted Tue Jan 1 2013 10:21:38 UTC (3 years 4 months 3 weeks 5 days 8 hours ago) and read 7158 times:

 Quoting JoeCanuck (Reply 14):Basically, ATC will give the planes time and space to execute a go-around in case of runway excursion. Everybody will know a crosswind runway is being used so everyone is ready to act if an incursion takes place. With proper spacing, time is allowed that even if the landing or taking off plane does cross the intersection, it will probably not be an issue. The plane just has to make it across the taxiway hashmarks to be clear of the main runway...which only takes a few seconds.

Or (at least in the US), they use LAHSO operations, if the pilots/airlines accept them.

 I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 JoeCanuck From Canada, joined Dec 2005, 6364 posts, RR: 33 Reply 16, posted Tue Jan 1 2013 15:57:03 UTC (3 years 4 months 3 weeks 5 days 2 hours ago) and read 7116 times:

I've done that in a Cherokee at YYC. Even with this, they still have to stagger the crosswind flights since an incursion could happen despite best efforts...but you don't need anywhere near the gap that all using the same runway would.

It's a bit of an awkward system but when it's working right, it's better than a single runway.

 What the...?
 alaska737 From United States of America, joined Feb 2006, 1063 posts, RR: 4 Reply 17, posted Tue Jan 1 2013 18:25:48 UTC (3 years 4 months 3 weeks 5 days ago) and read 7093 times:

 Quoting Starlionblue (Reply 10):Ok fair enough but it is well beyond the demonstrated max.

So...? And it isn't much beyond the demonstrated max just FYI.

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