747-600X From United States of America, joined Jan 2000, 2742 posts, RR: 17 Posted (11 years 1 month 2 weeks 5 days 22 hours ago) and read 1034 times:
Well... runway numbers are, apparently, based on the direction (in degrees) that the runway faces. So... what's zero? Due North? Okay... is it True North or Magnetic North? At Kansai International, a huge plan of which is hanging in front of me at this moment, the runway is at a precise 51-degree angle to True North, so you'd think that it would be numbered 05, given that only the first 2 digits of the three-(possible)-digit number are used. But no, it's actually 06. I assume that this is because the runway is at a 57-degree, 46-minute, 42-second angle to Magnetic North, which makes one wonder why they aligned it perfectly at 51-degrees with True North. Anyway... can someone please explain how exactly runways are numbered?
"Mental health is reality at all cost." -- M. Scott Peck, 'The Road Less Traveled'
Av8trxx From United States of America, joined Nov 2001, 657 posts, RR: 7 Reply 1, posted (11 years 1 month 2 weeks 5 days 22 hours ago) and read 977 times:
Runway numbers are taken from a compass heading, so they are all in magnetic, not true. 057 degrees rounds to 060, so that's why its Rwy 6. All runway numbers are rounded to their nearest 10 degree interval (to keep things simple I bet). True, north is zero, but 360 or Runway 36 is used. If it were at 005 degrees, I guess they could go either way, 360-Rwy 36 or 010-Rwy 10.
747-600X From United States of America, joined Jan 2000, 2742 posts, RR: 17 Reply 2, posted (11 years 1 month 2 weeks 5 days 22 hours ago) and read 961 times:
Okay, so my next question is - how do you find Magnetic North on a computer? Let's say you're designing an airport for France here in the USA... how do you know what angle to put it at without flying over there, pulling out the ol' compass, hoping you're standing at the right angle, and shooting?
"Mental health is reality at all cost." -- M. Scott Peck, 'The Road Less Traveled'
Hamfist From United States of America, joined Jan 2002, 614 posts, RR: 4 Reply 3, posted (11 years 1 month 2 weeks 5 days 22 hours ago) and read 950 times:
If memory serves me correct, from a brief intro to TERPS that I received, there may be a magnetic correction that is part of the determination.
Cessnapimp From Canada, joined Oct 2001, 1320 posts, RR: 23 Reply 4, posted (11 years 1 month 2 weeks 5 days 22 hours ago) and read 940 times:
In Canada,the airspace is divided in two as far as rwy orientation is concerned: We have the Southern Domestic airspace, and Northern domestic airspace. They split pretty much equally in the middle (longitudinally, of course) of the country. In the southern domestic airspace, the rwy numbers are in reference to the magnetic north: North would be rwy 36,181 degs would be rwy 18 etc...
Moving north of the country, magnetic variation lines (isogonic lines for you fancy shmancy people) behave errradically because you are getting close to the magnetic pole. This phenomena, known as "magnetic dip" causes the compass to behave erradically since you are beginning to overfly nature's big ass magnet. Therefore this zone up North requires all headings (including rwy orientation) to be in reference to the true north.
747-600X From United States of America, joined Jan 2000, 2742 posts, RR: 17 Reply 5, posted (11 years 1 month 2 weeks 5 days 21 hours ago) and read 922 times:
Next question - are the degrees taken clockwise or counterclockwise? If a runway points due North, it's 36, so if its 60 degrees to the left, is that Runway 30 (300 deg.) or runway 06 (60 deg.)??? I was under the assumption that the degrees always went counterclockwise, such that it would be Runway 06. Anyone know for sure?
"Mental health is reality at all cost." -- M. Scott Peck, 'The Road Less Traveled'
NZ767 From New Zealand, joined Nov 2001, 1620 posts, RR: 1 Reply 7, posted (11 years 1 month 2 weeks 5 days 21 hours ago) and read 904 times:
Talk about complicating a simple matter here.
Runway numbers are assigned according to the direction that they lie in relation to magnetic north rounded to the nearest tenth with the last digit dropped.
This is generally worldwide with the Canadian exception above; there may be others, eg: Antarctica could possibly follow the Canadian example (the other way around obviously) as regards the South Magnetic Pole.
Timz From United States of America, joined Sep 1999, 6468 posts, RR: 8 Reply 8, posted (11 years 1 month 2 weeks 5 days 21 hours ago) and read 893 times:
http://www.worldaerodata.com gives the difference betw magnetic and true at its hundreds (thousands?) of world airports.
747-600X From United States of America, joined Jan 2000, 2742 posts, RR: 17 Reply 9, posted (11 years 1 month 2 weeks 5 days 20 hours ago) and read 859 times:
Worldaerodata seems only to provide the True headings.
"Mental health is reality at all cost." -- M. Scott Peck, 'The Road Less Traveled'
747-600X From United States of America, joined Jan 2000, 2742 posts, RR: 17 Reply 10, posted (11 years 1 month 2 weeks 5 days 19 hours ago) and read 851 times:
Sorry, I was looking under the runway information. The basic airport info. does include a "magnetic variation".
"Mental health is reality at all cost." -- M. Scott Peck, 'The Road Less Traveled'
Jhooper From United States of America, joined Dec 2001, 6195 posts, RR: 13 Reply 11, posted (11 years 1 month 2 weeks 5 days 13 hours ago) and read 796 times:
It's interesting to note that sometimes airports renumber their runways. For example, RWY 14L/14R at Houston Intercontinental is now 15L/15R. The magnetic variation changes slowly over time.
Last year 1,944 New Yorkers saw something and said something.
Skymonster From , joined Dec 1969, posts, RR: Reply 12, posted (11 years 1 month 2 weeks 5 days 12 hours ago) and read 788 times:
It would be crazy to number runways anything other than in respect of magnetic north (with the exceptions mentioned previously). One of the basic checks that should be made before take off is: is the compass heading the same as the runway - its one of the ways of confirming you're on the right runway. Use anything other than magnetic and this basic safety check isn't possible.
BWIrwy4 From United States of America, joined Nov 2001, 940 posts, RR: 1 Reply 13, posted (11 years 1 month 2 weeks 5 days 12 hours ago) and read 783 times:
Who's planning on telling China Airlines about this basic safety check?
Kirstey From United Kingdom, joined Nov 2001, 110 posts, RR: 0 Reply 14, posted (11 years 1 month 2 weeks 5 days 11 hours ago) and read 750 times:
>Use anything other than magnetic and this basic safety check isn't possible
Of course Skymonster - you could use the great big white numbers on the Threshold!!!!
Alignment is based on Magnetic, because short of chucking it out of the window the compass is the only 100% reliable instrument on an aircraft. Everything else can go "Pete Tong" on a plane, the compass and the earths magnetic field will be fine!
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