<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by UAPremierExec:
At USAirways, an A321 pilot flies *ONLY* the A321, not the A320 or A319.... not like a UA 757 or 767 pilot can go from one plane to the other..</font>
Incorrect. First, I am nearly 100% sure that the 319/20/21 cockpits are almost identical. They get certified for the 320 family which includes the 321/20/19 and 18 if US ever goes that route. They can easily switch between these planes. Well... easily but there are tailstikes as paullevi mentioned!
They just can't switch into the 330.
But you are right about the economics of the A318. It's frame is a mini 319/20. It's smaller in length but has the same wingspan. And with the large engines it is just a heavy plane.