Just a couple of comments.
Roberta, what you are saying about the 345/346 (if ordered) fleet increasing from 5 to 20 aircraft, in terms of provide much better operating efficiency for this fleet of aircraft, is true. However, I think what Mlsrar is saying is that with a Boeing purchase, the 345s would probably be on removed from the fleet (whether it be a buy back deal by Boeing or whatever). This would present cost savings in terms of spare parts, crew scheduling, and things of that nature. I don't know the difference performance-wise (and don't want to start a debate about it), so I am going to leave those details out and just look at crew-scheduling, spare parts, etc. It will be a lot more efficient with crew scheduling to just operate one type instead of two.
As for the two types of jet engines. It has been discussed before that having commonality does tend to save in costs. However, there are airlines that operate the same types of aircraft with different engines. For example, BA
operates their 777s with both GE90 and RR
Trent engines. JAL operates both GE90 and PW
engines on their 777s...and those GEs are among the few that are operated by JAL in their longhaul fleet (if any? 747, 743, 744, 763, and M11 all P&W, right?). The GE
engines for BA
are the only GE
engines in their longhaul fleet too. Two types of engines will increase spare parts costs with the engines, but will this additional cost outweigh operating two types of aircraft (spares, crew scheudling, etc.). I am not saying one is better than the other, but each side has its advantages.