Here is the replacement default 'airlines.cfg' for FS2002. It works in FS2004 also. United is in the list.
http://www.simviation.com/fs2002misc1.htm 'FS2002 Airlines Callsigns file'
This will give you all default airlines in the 'ATC name' drop down list.
Or you can modify the 'aircraft.cfg' file for the your United ac. Works with or without the 'airlines.cfg' replacement file.
[fltsim.0]
title=Boeing 737-400
sim=Boeing737-400
model=
panel=
sound=
texture=
kb_checklists=Boeing737-400_check
kb_reference=Boeing737-400_ref
atc_id=N737Z
atc_airline=American Pacific<----change to United
atc_flight_number=1123
ui_manufacturer=Boeing
.............
Another reference for FS2002/4 default airlines plus type and models.
http://www.homepages.mcb.net/bones/04fs/download/downloads.htmIf you should ever need airline names not on the default list you'll need
Editvoicepack.
Dave
At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation. Igor Sikorsky
I intend to live forever....so far, so good. Steven Wright
You know....you can just rip up a to-do list.