.TH DIST 7 purdy
.CT 1 inst_info
.SH NAME
dist, dme, plan, path, cross \(mi aviation navigation
.SH SYNOPSIS
.B /usr/ken/bin/dist
.I obj obj ...
.PP
.B /usr/ken/bin/dme
.I obj radial dist
.PP
.B /usr/ken/bin/plan
[
.BI - dist1
[
.BI - dist2
]]
.I obj obj
.PP
.B /usr/ken/bin/path
[
.BI - dist
]
.I obj obj ...
.PP
.B /usr/ken/bin/cross
[
.BI - dist
]
.I obj
.SH DESCRIPTION
These routines provide navigation services
using an aviation database.
.I Objects
in the database are of four types:
VORs ending in 
.BR .v ,
airports ending in 
.BR .a ,
NDBs ending in 
.BR .n ,
and intersections ending in 
.BR .i .
An ambiguous object specified without
suffix is interpreted in the above order.
.PP
The canonical program in this series,
.IR dist ,
prints the magnetic bearing and distance in
nautical miles between a set of two or more specified objects.
The magnetic correction is applied at the first of a pair
of objects,
so the bearing from Morristown to San Diego is
281 degrees while the reverse is 50 degrees.
.I Dist
also prints a frequency for objects.
For VORs and NDBs,
the frequency is obvious.
For airports,
the frequency is sometimes the tower frequency,
sometimes UNICOM and sometimes zero.
Intersections have no frequency.
.PP
.I Dme
prints the latitude and longitude
of a point that is a bearing and distance from an object.
The format printed is the source form of the database of objects.
.I Dme
is used to create new objects for the database \(mi usually intersections.
.PP
.I Plan
finds a shortest distance from one object to another traveling
along a route of VORs.
The optional argument
.I dist1
is the maximum allowable distance between VORs
en route (default 100 nautical miles) and
.I dist2
is the maximum allowable distance between the starting
object and the first VOR and the last VOR and terminal object
(default 50).
.PP
.I Path
lists all objects in the database that lie
within
.I dist
(default 10 nautical miles)
of the great circle route between two objects.
If more than two arguments are given,
routes are calculated for each pair of objects.
The list is ordered by distance along the route.
The tangential distance to each object is given
with negative to the left and positive to the right.
.PP
.I Cross
prints all objects in the database
within
.I dist
(default 50 nautical miles)
from the given object.
.SH FILES
.TP /usr/ken/lib/obj
objects
.SH SEE ALSO
.IR avw (7)
.SH BUGS
The database is old and should not be used for navigation purposes.
.br
Frequencies for airports are inconsistent.
.br
.I Plan
uses low power (terminal) VORs when very often these
cannot be tracked from 50 miles.
.br
.I Plan
will cheerfully plan routes through prohibited areas,
over open water and over high mountains.
The only criterion is the distance between objects.
.br
.I Cross
has bugs.