How runways are marked


As much as I try, I can’t seem to keep it straight how runways are marked. As I understand it, runways are marked with the approximate truncated magnetic orientation, so KBWI’s main east west runway is 10-28 indicating that one end of the runway is approximately 100degrees and the other end approximately 280 degrees. So far I am with that, but when I look at an aerial photo, the marking seems to be on the other end of the runway. I’ve been told that it is based upon the approaching aircraft’s perspective, but it seems to me that if, for example, I am approaching BWI’s 10-28 I should be flying on a compass direction of 280 degrees if approaching from the east, and 110 degrees if approaching from the west. So what am I not understanding here? (BTW it should be obvious that I am NOT a pilot.)


Your original assumption is correct; when approaching runway 28, you ARE coming from the east towards the west, slightly more to the NW than due W (270 degrees). Runway 10 is west-to-east. If you look at BWI’s Live Activity page and click on the airport’s layout at the top of the page (center), you’ll see that the layout is exactly how you say it SHOULD be. There’s no irregularity there.


O.K., so the end of the runway you get to first shows the magnetic heading/direction you are going toward?


Actually the original poster has a very valid question regarding approaches.

One would think the approach heading for runway 10 is 100 degrees on the compass rose, but it’s not.

Look at the GPS and ILS approaches and you will see that the approach is 105 degrees which is a full 5 degrees off of runway headiong. Conversly, runway 28 has a heading of 285 for the final approach phase.

So, the approach is not “exactly” the heading of the runway centerline. People standing at the end of the runway probably won’t see the 5 degree heading difference, but it sure makes a difference sliding down the glide slope!

As you may (or may not know) approaches may dog leg you in for the initial approach phase for obstacle clearance issues. Unless it’s a circle to approach phase, GENERALLY the final approach will be runway heading within a certain number of degrees (don’t know the exact number)



Yes, in a general sense. See my other post for a more technical posting.

If you are heading south to land, you will see runway 18 (heading 180). If you are headed north, you will see runway 36 (heading 360). If you are headed east, you will see runway niner (heading 090), and west, you will see runway 27 (heading 270)



To make it simple, use an East West runway.
You are going to land on runway 27.
You are approaching the runway from the East because you are headed West.
The part that throws people is that the number 27 is painted on the East end of the runway.


That’s because rwy 10’s actual heading is 105.2 degrees, and 28’s is 285.2 degrees. There is no offset of the FAC at KBWI.

Magnetic variation changes over time as well, in some areas by more than a degree a decade. This will actually cause runways to be renumbered from time to time, for example KROG (where I am based) former rwy 1/19 is now 2/20. The runway didn’t move, but the magnetic North Pole did!