Originally Posted by
UNITED959
This is true. What I'm confused over...is they're simply changing the runway's numbers from 9/27 to 10/28. But they're not physically rotating the runway 10 degrees.
LAX is the same way...the 4 runways are parallel, but they are 7/25LR and 6/24LR. I guess there are special notes on the approach charts to alert pilots that a heading correction is necessary.
Great point. The reason they can do this is that the ORD runways are at approximately 93/273 degrees. Thus, they currently round down to "Runway 9," but they can also round the same runways up to "Runway 10," without physically rotating the runways.
See
http://download.aopa.org/ustprocs/20...ms/00166AD.PDF
LAX does the same thing. All four runways are at 249.8 degrees. So they round two down to "Runway 24" and the other two up to "Runway 25."
See
http://download.aopa.org/ustprocs/20...ms/00237AD.PDF
Off-topic, but interestingly, sometimes a runway heading DOES change, even when the runway does not physically move. The runway headings are based on magnetic north, not true north. Magnetic north "moves" at a very slow rate. Thus, a runway heading might eventually have to be changed, because its magnetic direction has changed. An example of this is the Palo Alto municipal airport (PAO). It used to have runway 12/30, but a few years ago they had to rename it 13/31, because of the magnetic variation.