The ability to borrow funds seems to vary greatly with the week, the day of the week, and time of the day.
This seriously impedes planning and forces one to schedule their time to the game's schedule.
The maximum amount an airline can borrow should be a "smooth" function, moving at a graduated and more predictable pace. There should not be a great difference between weeks and between days of the week.
I'm not sure this needs to be a "major" change. I imagine the algorithm could be tweaked to look at a wider span of time across the same factors it does now, perhaps a weighted average, with recent factors getting higher weights (or perhaps attenuating extra large impacts like arrival of purchased aircraft, tax payments, etc. in current week) .
I know it has been mentioned before, but I raise this again as nobody specifically mentioned the impact to game playability (which probably disproportionately hits noobs with smaller airlines, restarted airlines), as some of us have real life commitments we have difficulty (or simply cannot) work around . http://www.airwaysim.com/forum/index.php/topic,48421.0.html