M-750 航路經我北方 air route as it passes north of me


Here in central Taiwan, the M-750 air route from Hong Kong to Japan passes a few kilometers from me. I will use the stars behind the planes to determine their height.

How far north of me does the plane pass? Computations from background stars 由飛機經北方星計算其高度

My netnews query results gave me confidence that planes follow their routes well. So, looking at the charts on Vatroc and also maybe looking up individual points, and using my own coordinates, I find route M-750 crosses 9338 meters due north of me. (See makefile, section how_far_north)

I wrote a python script to determine elevations from what stars the plane passes between. Here are results for several sample levels:

 7000 36.9 77.3  7777 25515
 8000 40.6 73.6  8777 28795
 9000 43.9 70.2  9777 32076
10000 47.0 67.2 10777 35357
11000 49.7 64.5 11777 38638
12000 52.1 62.1 12777 41919
13000 54.3 59.9 13777 45200
14000 56.3 57.9 14777 48480

Meters above surface
Angle above my horizon
Declination on star chart at the north-south meridian
Meters above mean sea level
Feet above mean sea level

I will lie in wait with binoculars for a plane to pass. As it passes above polaris (the north star), I will note what stars it is passing between, and consulting a star atlas or program, I will find the declination of those stars and thus the plane. Then from the above table, I will estimate their height.

Here are some bright stars I might consider for reference as they pass over the meridian (straight up from polaris). (See makefile, section star)

Declination, right ascension, constellation, name, magnitude
59:8:59   0:9:10.7    Cas  Beta   2.27
60:14:7   1:25:49     Cas  Delta  2.68
60:43:0   0:56:42.5   Cas  Gamma  2.47
61:30:51  16:23:59.5  Dra  Eta    2.74
61:45:3   11:3:43.7   UMa  Alpha  1.79
62:35:8   21:18:34.8  Cep  Alpha  2.44
74:9:20   14:50:42.3  UMi  Beta   2.08

I am careful not to mention "flight levels", as those are related to air pressure.

積丹尼 Dan Jidanni Jacobson

Last modified: 2013-02-12 13:07:29 +0800