I am always uncertain when one tries to predict a FUTURE Value. Let me explain a bit more by using analogy
Some of my newbie analytics friends (I am also a newbie in analytics), for example like to predict stock price based on old existing prices. - they call it technical analysis. I always disagrees with them. Why ? Because if technical analysis based on old stock price can predict future price, then all businessmen namely the founders or ceo like Google or Microsoft should stop providing a service and they can simply sit back at their desks, doing analytics on prediction of stock price and attempt to make $. Worse ..people come out with a lot of wrong info by using existing old prices and convert them to moving averages, etc when PRICE itself is not a good independent variable.
For me I believe in fundamental analysis, which is to use BUSINESS RATIOS to determine the future up or down of a stock price. Ratios are determine by humans or employee workings in a company that generate profit or loss, etc.
Now back to your airline analysis - rather than predict the future passengers load (if I am not wrong - is this what you are trying to predict ?), why not determine the FEATURES that determine the UP OR DOWN of the passenger outcomes ? Example, you can use feature engineering to determine which features are most important or has most impact to passenger load trend ?
I've NOT study the ARIMA story, etc Perhaps I am really wrong in understanding analytics.