Welcome to Librarium Online!
Had a 1000 point game against my Tau playing friend today, it was the first time I fielded Banshees, they took out a couple of broadsides, and some pathfinders, however I lost 2 banshees to fire warriors as soon as they disembarked from the Wave Serpent.
am I doing anything wrong or is this normal? and can this be justified as acceptable losses?
You mean you lost 2 models or two squads? I wouldn't exactly be worried about losing two models. I just don't know how they got killed after disembarking, I usually don't disembark unless I know I'll be able to charge that same turn.
Losing 2 models in exchange for 2 enemy squads is always a good thing in my book.
As SJPhillyVT mentioned, you do not disembark a squad if they cannot make a successful charge in the same turn. You disembark 2", fleet average 3", and charge 6", giving you around 11-12 inch charge. Not too shabby! Against opponents like Tau i would always try to make a multiple charge into as many units as possible, so try to maneuver with those 12 inches of charge to the highest efficiency.
Hope this helped.
To me it sounds like you disembarked your Banshees after moving, is this correct? If so you should let them remain in the Wave Serpent and then disembark on your next turn, that way the enemy will not be able to shoot you before you get to assault. With fleet and good positioning you should rarely fail with this tactic. Disembarking after moving is only good for ranged units like Dire Avengers of Fire Dragons, assault units should always remain in the transports until your next turn.
It was only two models, but I ran them as a squad of 6 so it was 1/3 of the damage they put out.
Cheers for the help everyone