Friday, July 15, 2016

back to counting planes...


Been back online with my ADS-B receiver for 2 1/2 days now.  We shall see if I lose the other two ports on my router - it is placed with plenty of breathing room now and I have the backup router ready and waiting...just in case.  Today's tally so far from what I picked up from my humble little station maxed out at 30,296 pings yielding 4,336 positions on some of the 709 aircraft seen today from a maximum distance of 209 nautical miles (which is 240 miles to you and me).  90,102,80,0,B

3 comments:

Sam Finn said...

I'm sure there must be a good reason but nautical miles for airplanes?

Margery Bills said...

Don't you see more than all the map work? (My daughter is on vacation in Costa Rica now. Must be nice.)

Unknown said...

Sam Finn, airplanes, like ships use nautical miles for navigational reasons. The statute mile is an arbitrary length of no particular significance in navigation. However, the significance of a nautical mile (and the speed unit knots) is that it's equal to 1 minute of arc (1/60 degree) of latitude along any meridian. When navigating over long distances you want to use a unit of measurement that is directly related to latitude and longitude. Also if you know your latitude, you also know the factor to determine what 1 minute of longitude is.

Also due to the way most navigational charts are made (mercator projection) using nautical miles make using them much more convenient.

I imagine with almost universal use of computerized navigation (both inertial and satellite) the necessity of nautical miles greatly diminishes. However it lives on out of tradition and also to remain in sync with manual navigation in order for us to fall back to when the machine stops!