Re: 200 Applications?
A few years ago I worked for a far more modern and competent airline than BA and I can assure you that 200 interdependent systems is not unusual.
Running an airline is a very complex business and there are a lot of factors that need to be accounted for. It's not just the airline itself either; it has to communicate with the systems in the airport too, and this is true for all of the outstations too.