Danger said:
I'd appreciate some help understanding the information EF provides. For example,
F6 A6 J9 C9 D9 I0 B9 H9 K9 M9 R9 L9 V9 S0 N0 Q0 O0 X0 E0
What letters do I look at to try to work out how many seats are still available in economy?
What letters do I look at to try to work out how many upgrade seats are still available (from discount economy to business)?
There are at least 9 seats available in economy, but none at the very cheapest fares. Given reasonably discounted booking classes show availability at 9 it looks a fairly empty flight at this stage.
Care is needed in interpreting the booking class availability as there are wide differences in how bookings go for routes and even particular flights on the same route.
Some may be oversold by lots, if the airline expects a lot of no shows or is willing to operationally upgrade (op-up) passengers. Obviously to op-up the next highest class of service needs room, and maybe even first class if they need to move some pax out of business to make room for op-ups from economy. Different routes/flights/dates will affect how willing the airline is to oversell (and by how many). Each airline will base its own experience for the specific flight to determine the optimum number.
Even without oversold situations there is care needed in interpreting due to the arcane ways of revenue or yield management. For example availability in a certain booking class may be restricted to certain fares (eg allow round trip discounted business but no more RTW business - both of which use the same booking class), to certain markets (eg allow sales ex-Oz for SYD-LAX but not ex-US), to through fares (eg allow SYD-SIN if it is part of SYD-LHR) or excluding through fares (eg allow SYD-SIN only if SIN is the destination). Etc.
Airlines may remove availability even without a sale, or add more availability, if their view on what level of fares they can get for the remaining seats changes.
It takes practice to see how airlines handle these and observe the effect on the booking class availability, and what it means in terms of being able to buy seats, how many and when, upgrade chances (either paid for or op-up), award availability, chances of getting spare seats beside you, etc.