[Scan-DC] Parallel Runways at Dulles?

[sdaitch at KUW.IBB.GOV]

Jordan,

I got to thinking about the parallel situation, and I don't 
think the fact the two runways have slightly different 
headings, 11.0 degrees for 1C, and 11.1 degrees for 1R,
doesn't mean they are not parallel.

Remember, lines of longitude converge at the North and South
Poles, so two north-south lines with the exact same heading
separated by some distance would not be exactly parallel.  

In other words, someone heading 360 degrees true 
from Atlanta, and someone else heading 360 degrees true from 
San Francisco, will eventually meet at the North Pole.  

The only way to determine the parallelism of the two runways is
to compare the centerline spacing at the north end of the runways
and the centerline spacing at the south end of the runways.

My guess, and this is a guess only, is the two runways really 
are parallel and the difference in the headings is due to the 
convergence of lines of longitude.  

Just an academic thought.

73
Sheldon



----- Original Message -----
From: Jordan Hayes <jmhayes at speakeasy.net>
Date: Sunday, June 8, 2008 7:49 pm
Subject: Re: [Scan-DC] Dulles Gets New Runway (name, at least)

> Go to airnav dot com and click airports, type in IAD, and download 
> the 
> PDF of the airport diagram for more details.
> 
> Fun fact: 19C and 19L aren't exactly parallel.
> 
> /jordan