Friday, July 08, 2005

Runway Numbers

I just watched a movie where Kurt Russell is a mild-mannered intelligence operative who has to land a B747 because the bad guys have killed the pilots. You know, the sort of thing that happens every week in Hollywood aviation.

He's initally cleared to land on "runway one ell north." That's right, not "one left" but "one ell" plus the designation north. If that doesn't strike you as odd, let me explain how real (non-Hollywood) runway numbers work. Under normal circumstances, a runway is named after the direction you would be going while landing on it, rounded to the nearest ten degrees. So at Downsview, the runway runs northwest-southeast, such that aircraft landing on it would be on a heading of 150 degrees or 330 degrees, depending on which end they were facing. They might be landing on runway 15 (pronounced "one-five") or 33 (pronounced "three-three"). The entire piece of pavement is runway 15/33. If there is more than one runway at the same airport, with the same heading, then they are designated as left and right, and centre if necessary. The pavement markings say 26L and the pilots and air traffic controllers say "two-six left." Okay, most of you knew all that, but I'm trying to be accessible here.

Now when a large international airport has too many parallel runways to get by with "left" "right" and "centre" (or "center" for the Americans), they simply pretend that some of them have a slightly different heading. So Toronto has a 24L/06R and a 24R/06L and another runway, exact same heading of 237 degrees magnetic, but instead of renaming 24R to 24C, and giving the name 24R to the new runway, they pretend that the rightmost runway has a slightly different heading, and call it runway 23. That's allowed. I'm even going to allow for the possibility that a large airport could come up with a slightly non-standard scheme to disambiguate half a dozen parallel runways. But "one left north"? Runway one left already runs north-south, if there were two of them, you'd want an east and a west, not a north and a south.

Our intrepid hero doesn't land on runway one ell north. He comes in too high and is then afraid to turn around. He decides to land at another airport--on runway two-six. Apparently he can turn through 110 degrees just fine. He does land on that runway, although you don't see the arrival end as he touches down. The final touch is that as he runs off the other end (the runway is too short) you see that the other end of the runway is marked with a seven. I guess the runway curves.

Oh and one of the odd things about Americans is that they leave the initial zero off of runway designations. The above would be runway "zero seven" in Canada. I always think single digit runway numbers look very rural and hicktown. Maybe it's because middle-of-nowhere airports don't have parallel runways so a three digit designator like 33L is indicative of a big city. By induction, only one digit implies a town so small I expect dogs to be sleeping in the middle of Main Street.


Old Blind Dog said...

The magnetic heading of runway "07" would be 007°. Runway "7", on the other hand, would be 070°. ;-)

Aviatrix said...

Eh OBD? By that logic the heading of runway 17 would be 017°. In Canada, in every case you put a 0 after the number to get the magnetic heading of the runway. (Or to get the true heading in northern domestic airspace, but that's another story).

Does ATC tell you to fly heafing "zero-seven-zero" or "seven-zero"?

And Rubberducky, Segal has a cameo and dies ignobly! Second best part of the movie.

Avimentor said...

Centre, center; RWY 07, Rwy 7; Heading, Heafing ... Oh, can't we all just get along! ;-)

Animals on the runway is a whole 'nother topic, but I took off yesterday from runway 28L and had to cycle my prop to scare a coyote out of my way. I suspect that after leaving the airport, the coyote returned to napping on Main Street.

Anonymous said...

I suppose until you are used to it, the checking of the bearing by seeing if the two numbers are 180 apart, is a trifle cumbersome.
As far as Americans and their spelling, blame Webster and his dictionary.

Aviatrix said...

Can't say I've ever checked. If they clear me to land on 31 I'm just assuming the other end of the runway says 13, without checking. You get used to the pairs of numbers that denote runway ends though, there are only eighteen possibilities, and once you know airports with them all there's no more thinking involved. Some of them roll off the tongue easier tha others, though.

01-19, 02-20, 03-21, 04-22, 05-23, 06-24, 07-25, 08-26, 09-27, 10-28, 11-29, 12-30, 13-31, 14-32, 15-33,
16-34, 17-35, 18-36

There's another trick, too. Take the two-digits of the number from one end of the runway and subtract 2 from one digit while adding 2 to the other. Now you have the opposite runway. It doesn't work if both digits are less than 2: then you add 18.

dibabear said...

Frankfurt (EDDF) has a stacked ILS so that two runways become three. 25R, 25L and (IIRC 26...too lazy to look up the chart). 25L actually has two ILS glideslopes, one that leads to the threshold of 25L and another that leads to a point about 1/3 to halfway down the runway. This "runway" is marked as 26 in the directory.

The logic of this is that 25L and 25R are too close together to permit parallel landing operations so, for aircraft that don't need 12000 feet of asphalt, there is a second glideslope that is high enough to permit parallel ops.

Old Blind Dog said...

Sorry to come back to this conversation late, yesterday/today was moving day. Anyway, runway "17" would be 170º. The rule on the runway designations is that no runway begins with a "0". Runways are always cardinal headings, i.e. 1, 2, 3....9, 10, 11, etc. and are designated by the nearest cardinal heading to their actual heading. Runway 18, for instance might be 185º, whereas runway 19 might be 187º or 193º and so on. I'm fairly certain that when the magnetic heading changes the runway has to be redesignated (whether or not the city council wants to come up with the money), but I could be wrong. Anyway, I sure most of you know all this info, I was just teasing a little in the first comment. And, yes, ATC says, "fly heading zero seven zero".

Scott Johnson said...

Atlanta (Hartsfield) is one of those airports with lots of parallel runways. There are presently four, all oriented 092 - 272. The northern pair are 8/26 L/R, and the southern pair are 9/27 L/R. They're currently constructing a fifth runway, south of and parallel to the other four. My friends and I are taking bets as to what its numbers will be. I'm thinking it'll be 10/28.

Marie said...

Speaking of runway confusion, what did you think of the mixup at Lexington, KY airport, when the pilots of a Comair took off from the wrong runway (a shorter one), which then crashed upon takeoff, killing 49 aboard? They were supposed to take 22 and they ended up on 26. I realize this is magnetic headings, but to a non-pilot, the numbers 22 and 26 to me could get easily mixed up, especially if one were tired, having arrived at the airport at 5 am. Why can't airports put warning or caution signs next to certain runway signs, such as "CAUTION, SHORT RUNWAY". Wouldn't that help?

Aviatrix said...

I've noticed a lot of hits on my blog searching for "runway numbers" since the accident. Have a look at the FL390 and FL250 blogs in my sidebar for some discussion.

While I understand that a "short runway" warning might seem to make sense to a non-pilot, the truth is that the presence of the sign would pose more danger than it would avert.

Airplanes vary so much. A 3500' runway is just great for my operations. It is the pilot's job to know how much runway is required for the weight of the airplane, the temperature, the elevation and so on.

Anonymous said...

In Tucson why is the main runway which lies on a heading of 135/315 called 110/290?

Aviatrix said...

The main airport in Tucson has three runways. The main runway is on a heading of 123/303 designated 11L/29R. That's a little bit off, but I guess they haven't got around to renumbering it to 12L/30R yet. There is also a shorter parallel runway designated 11R/29L, and a 03/21 on a heading of 033/213.

In Tuscon the magnetic variation is 12 degrees, meaning that 135 true is 123 magnetic. So the runway you think of "on a heading of 135/315" is really runway 11L/29R.