Are you familiar with the US Airways fare codes, and how they now turn into American Airlines fare letters? Most of the codes stayed the same, however there are a few differences.
The US Airways fare codes are on the left; The American Airlines codes are on the right.
Y->Y
B->B
M->H
H->K
Q->M
N->L
V->W
L->V
S->G
K->S
U->N
E->Q
R->E
Nick says
When will they align fare codes for domestic first class and ‘international’ business class? Still seeing PHX-MEX at 30k for ‘first class’ and not business class.