8 ms·
yellowbkpk explained one reason: we fly with magnetic compasses, so we need the runways to be magnetic as well. Even if we could come up with a safe and reliab
by lucasjung 16y ago
yellowbkpk explained one reason: we fly with magnetic compasses, so we need the runways to be magnetic as well.
Even if we could come up with a safe and reliable way to always have true heading displayed in the cockpit, there remains a very pragmatic reason for keeping runway numbers magnetic rather than true: under the current system, we have to change a few runways every once in a great while; if we switched systems, we would have to change every runway in the whole world all at once. It's not just a simple matter of re-painting the runways: publications have to be changed, notices have to be issued, etc. Changes would cascade out into literally every aspect of the aviation industry.
- hugh3 16y agoThis is all fine and dandy until the next geomagnetic reversal, at which point we suddenly find everything 180 degrees out of phase.
- AndrewDucker 16y agoThankfully, runways are numbered with _both_ numbers. So 18/36 or 9/27. Total reversal would leave the numbers the same...
- rlpb 16y agoEach number labels one direction/end, so they'd still have to be swapped round.
- yogipatel 16y agoNo, they'd still have to be swapped (under the current scheme of runway numbering). If you're landing on runway 18, you know your compass better be reading ~180° (after correction for deviation). Similarly, when taking off from runway 18, your compass should read the same. You can see just how much the magnetic variation changes around the world in this graphic: http://en.wikipedia.org/wiki/File:Earth_Magnetic_Field_Declination_from_1590_to_1990.gif http://en.wikipedia.org/wiki/File:Earth_Magnetic_Field_Decli...