Originally Posted by
xliioper
K/L/T basis = P (e.g. KAA2AQFN)
S/W/V basis = Z (e.g. WAA2KKFN)
Q/H/U basis = D (e.g. QAA2AFFN)
E/M/B/Y basis = C (e.g. EAA0AFFN)
Yes, the mapping is well-defined on domestic routes, and this is it. The relevant characters from the current domestic format are in first and seventh position, eg
WAA2KK
FN. W has a secondary inventory of W (and books into Z), and F indicates it is a First fare.
The last two characters together determine the class and type of fare:
BN, BS: Basic Economy (BS for specials)
DN, DS: Deep Discount Economy (DS for specials)
ER, EX: Deep Discount Economy, combines only with higher fares (cannot be combined with type DN, DS, ER, EX or Basic Economy, X for specials)
EN: Economy Restricted
EY: Economy Flexible
FN: First Restricted
FY: First Flexible