The category "<air_call_sign_prefix>" can be expressed as follows:
<air_call_sign_prefix-not_takes_digit> <digit>
ali
angel
apollo
aragon
armstrong
auntie
backdoor
badger
batman
bedlam
bengal
benoit
bifocal
bigdog
birdman
blacktie
blazer
bluebell
boot
bottle
brainy
bug
bugsy
bull
bulldog
c j
cancer
capone
charger
charlie juliet
chevy
chrystler
city
clydesdale
coattail
coffee
collie
combat
comic
condor
cousin
crab
crusader
cuervo
cyber
daisy
daniel
devil
diamond
digger
donald
dopey
dragon
eagle
earshot
easter
edsel
eightball
es
eternal
ewing
eyebrow
falcon
father
feather
fina
flush
force
forger
freighter
frog
fuel
gator
glider
goad
golden
goldfish
goodyear
goofy
gouge
greenthumb
gunslinger
gypsy
hades
hagler
heartbreak
hogan
holy
hookey
hoya
huey
insane
jaguar
jarrett
jaws
jester
joker
jordan
jovial
kansas
kristy
laker
lancer
lewis
lighthouse
little
loco
loner
lookout
louie
maggie
magic
mankind
medieval
method
mickey
micron
mocha
mother
mousetrap
mustang
myopia
napper
nat
network
nugget
octane
opus
outlaw
owen
panther
patriot
pernell
peter
pillman
pinky
pinto
pippen
pitbull
player
plumber
plymouth
pole
polly
poodle
portland
rabbit
raekwon
raider
ranger
ratty
raven
reaper
redneck
repair
riddick
rocket
roman
royal
s n
sailboat
sandman
scrub
sea shadow
seahawk
seeker
sentinal
shamrock
sharky
shoe
sierra november
silver
silver eagle
sinbad
sister
slowpoke
snake
sneaky
sneezy
sock
socket
spotlight
stackhouse
stallion
steeler
steiner
stik
stormfront
student
subway
talent
tango victor
tequilla
tevin
tiger
tiny
tomcat
tv
uncle
vandam
venus
vidar
vodka
wildcat
wineglass
winnie
wizard
wolfpack
woody
worthy
xena
zapper
zeus
zippy