News accounts of radio communication from US 1549 have the captain saying this:

"Aaah, this is Cactus 1549, we lost thrust in both engines. We are turning back toward LaGuardia."

Why does the captain refer to his plane as "Cactus" 1549, and not US-Airways 1549?

Does "Cactus" refer to the fact that US was taken over by America West - and their HQ (Tempe AZ) is where you can find lots of cactus (cactii ?) ?