
Let's go to the B737 UAL file in your FS folder.
Click on my computer
Click c:
click on program file
click on microsoft games
FS folder
click aircraft folder
click on your B737 UAL folder
click on aircraft cfg file now you will see something like this:
[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
atc_flight_number=1123
ui_manufacturer=Boeing
ui_type="737-400"
ui_variation="American Pacific Airways"
atc_parking_types_=Gate Medium <..........type this
atc_parking_Codes=UAL <.........type this

click on file at the top save as
click save
click yes
that's it
let me know when you do this
dy