Runways are aligned with the prevailing winds in the area, such that aircraft can land along either direction depending on the wind. The uphill/downhill slope thing would require twice as many runways per airport lest pilots be stuck trying to take off uphill into the wind.
About the closest I can think of to that is some mountain airports that do all takeoffs one way and all landings the other. I’m not aware of any of those with more than one runway and traffic is usually extremely limited.
Wouldn't this whole problem disappear if runways were designed differently, at the minimum one exclusive for landing and one for takeoff with no chance for planes landing and planes taking off to meet, like 2 parallel hockey sticks.
Both runways would be painted and lit up completely differently with large lettering explicitly saying take off and landing.
> If they need more capacity they’ll build parallel runways which will be named with a suffix, like 9L and 9R.
There are even some airports that have three runways with the same heading, so they have "L", "C", and "R". (Two examples that I've personally took off or landed on all three of are 17/35 at DFW and 01/19 at IAD.)
> This same argument could apply to airfields, but airfields "above" neighbouring geography are pretty rare.
Take a look at Congonhas (https://en.wikipedia.org/wiki/S%C3%A3o_Paulo%E2%80%93Congonh...), it's a very busy airport right in the middle of a major city, and its runway sits higher than the roof of many of its adjacent buildings. As a passenger, landing there feels like you are going to land on top of the buildings until the last second. If a plane overruns the runway, it'll go downwards, cross a major road, and hit a building on the other side (yes, this has happened: https://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054).
The thing that’s unique about this airport is that it has parallel runways, which is very common, but the R runways (right side on approach) do not have right traffic. They also have a left traffic pattern. So two planes taking off at the same time will both make a left turn. Very unusual and very dangerous if you happen to have that situation.
And also so when they get cleared for “runway 15” they know which side to come on without having to consult a chart.
Also so there’s no confusion, each direction is named, so a runway that runs due North-South will be Runway 36 in the northern direction, and 18 to the south.
In practice it is rare for all but the largest airports to have more than 3 or 4 runways so it isn’t like there will be a Runway 2 and a Runway 3 at the same airport. If they need more capacity they’ll build parallel runways which will be named with a suffix, like 9L and 9R.
(Also, magnetic compasses aren’t that accurate in the first place, since there’s iron in the engines if nothing else. In theory there should be a compensation/calibration done with the results on a card, but, no guarantees that it’s done or up to date).
It’s really odd. If they use the 09 runways and the 27 runways (depending on wind on any given day) then you have left traffic in the pattern on the north or south side. It could be some weird compromise with the neighbors about only having traffic on one side at a time. I really have no idea. But noise abatement in urban areas is a big deal so if it’s not geography the I’d guess it’s noise. I’m just a private pilot so maybe an ATP here can weigh in. I’ll ask around.
For a counter example look at Centennial in Colorado (KAPA) which had a similar setup and is my home field. They always have right traffic on one of the runways.
Except that the essential description of a runway is its direction. It would be a lot more painful if you had to look up the direction of every runway.
The article doesn't mention why there can't be parallel takeoffs. Does anyone know why?
Looking at
the airport on Google Maps it appears there's quite some space between the runways. Perhaps the required flight paths after takeoff intersect?
As a side note, sometimes they are painted to move forward the runway beginning. The runway itself it´s still hard and usable, but they want you to land and takeoff further ahead from the real beginning, to reduce the noise at the proximity of the airport and the approach route (the planes flight higher at a given point if you move forward the runway)
> I would imagine light patterns would mark a runway as take-off, landing, or neither (plane crossing, etc)
It's often both, and the direction depends on the wind. It's better for planes to take off into the wind, so as the weather changes runway usage also changes accordingly during the day.
Or were you thinking the lights would change minute by minute based on the next designated usage. That might work! "Now it's a landing runway so it's blinking blue" kind of a thing. So nobody tries to take off or cross it. Or, then when someone is supposed to take off it's blinking yellow so planes landing on it won't be confused.
As far as I know, airports try to setup the operations to have planes descend over cities, and climb away from them, to minimize noise. Sometimes this is not possible because of winds, so there will be a reversal.
Sometimes it's not possible to avoid climbing over cities because the city ended up engulfing the airport (e.g. Heathrow) - so they will alternate directions to give various towns a break.
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