Re: Air traffic control questions

From:         greg@bronze.ucs.indiana.edu (Gregory R. TRAVIS)
Organization: Indiana University
Date:         08 Jun 94 21:53:29 
References:   1
Followups:    1
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In <airliners.1994.1313@ohare.Chicago.COM> katie@physics2.berkeley.edu (Katie Schwarz) writes:

>I like to listen to the air traffic control talk that United sometimes
>puts on one of the audio entertainment channels, and I have some naive
>questions about it. My impression is that after the pilot calls the
>ARTCC (Oakland Center, Denver Center, Indianapolis Center, etc) the
>person on the ground finds the aircraft on radar and follows it. Is
>this right?

Yes, when the aircrat can be radar identified.  It's not the controller's
only job, though.  Note also that air traffic control can FUNCTION perfectly
well without radar; it does so by reverting to "manual" callouts of
position location by aircraft pilot's and a lot of distance/time calculations
on the ground.  Radar just increases the ATC facilities "bandwidth" or absolute
# of planes in the sky.

>If so, what area is completely covered by radar (contiguous
>United States? North America?

Not even the contiguous United Stats is completely covered by radar, at least
not at low altitudes (0-7,000 feet above ground)

>How far can the radar follow a plane flying
>across an ocean?

Depending on the facility, 50-200 miles from shore with 100 miles a pretty
good average.

>How does the ground control know which aircraft they're seeing -- by the
>transponder? I don't remember ever hearing the controllers ask "what are
>you squawking?" although I think the plane is told what to squawk before
>taking off; why don't they need to ask?

The Air Traffic Control computers will automatically translate a recieved
transponder "sqawk" into a registration ("N" for US aircraft) number.
The computer will display the registration number on the controller's screen.

>Also, what's happening with the new air traffic control software that IBM
>is supposed to be developing? Why is it behind schedule and over budget?

I got three acronyms for you:

	LAN's, GUIs, and MIPS

Over designed, over engineered, over budget and over time.  A perfect
example of the second-system effect.

greg