Transcon navigation question


#1

Please forgive me, but I have a question about transcontinental navigation.
I’ve noticed when tracking some flights there are all these letters and number configurations. Is this part of an internal nav system or are they something else. I’ve always wondered. Perhaps there’s a link that would help me understand.
There’s one particular Falcon 50 I watch quite often and would like to know more about how they are able to fly such straight lines to their destinations.

Thanks -


#2

THIS THREAD will help explain “Airways”, “NavAids” and “Fixes”. Keep in mind that three-letter combinations are navaids (usually VORs), and five-letter combinations are fixes.
THIS WIKI PAGE explains VOR Navigation.

Hope this helps…


#3

Also check out discussions.flightaware.com/view … oordinates for GPS direct flights where the line is straigher then going the old fashion airways, VORS and such…

Allen


#4

Good point, Allen. I forgot that coordinates sometimes show up in the routes too. I think maybe the word “transcon” made me automatically think airways. Can you get cleared direct from JFK to LAX, or any long distance flight like that on an IFR flight plan? I think I read somewhere that you can file it that way, but you won’t get it, but I dunno…


#5

You can get it, but usually only at 3AM. The ATC computers only have a limited database that covers all fixes in their airspace as well as those in the adjacent centers. That is why they really like you to file either one fix in each centers airspace you are flying through, OR, ir you really want to fly direct use lattitude/longitude. The ATC computer will be able to calculate your projected route that way. Why only in the middle of the night? Because there are not nearly as many aircraft out there to miss, also most military airspace is available for civilian use at those hours.

On the flight plan you have three letter fixes which are ground based navigational aids (navaids), four letters and its an airport, five are intersections. When you see a V or J these are the assigned designations for a Victor (low altitude) or Jet (high altitude) airway.

Straight line, long distance navigation these days is usually done using GPS. Other systems that are capable are INS (Inertial Navigation), LORAN, or a flight management computer using any combination of these and/or short range VOR/DME navaids to calculate present position. If the FMC knows its present position it is able to then calculate a course to anywhere you tell it to go.

John


#6

LORAN? What’s that?? 8)


#7

See en.wikipedia.org/wiki/LORAN


#8

Rotary phone
Typrewriter
8-track


#9

Except for my mother-in-laws rotary phone those are all collectibles. Loran on the other hand is still in use. Not widely, but our tax dollars are still supporting it.

John


#10

Allen, I was being slightly sarcastic :slight_smile:

Go ahead and add Commodore 64 and Atari 2600 to that list…not to mention reel-to-reel movies…


#11

And 35mm file cameras :smiley:


#12

You youngsters…

You forgot about the Commodore Vic 20.


#13

…and don’t forget about the “TRASH-80”! (Radio Shack TRS-80) :mrgreen:
…and floppy disks/drives.


#14

There is an AOPA proposal to save LORAN as a back up to GPS.