I'm trying to figure out the formula behind our decision-making when considering a flight on a budget airline.

So far, the algorithm looks something like this: X - Y ÷ Z = A.

X, of course, is the money saved. Y represents the perceived chance of inconvenience (will the flight be late? Will the plane get diverted?), while Z is customer satisfaction (do you get a patriotic buzz from seeing hobbits in the safety video?).

I'm lousy at maths, but I know the value of a buck. When planning our family's flight to Queenstown to visit the in-laws for Christmas, there was a $400 difference between Air New Zealand and Jetstar.


That's the X-factor.

For me, there's a prominent Y-factor. A couple of years ago, when flying into Queenstown with Jetstar, we got diverted to Invercargill because of fog. From there, we had a three-hour bus ride to Queenstown - an unexpected journey, indeed.

Colin Hogg's excellent series on New Zealand's "Hidden Gems" sang the praises of Invercargill a fortnight ago and having lived there years ago, I was curious to see how the old town was looking. But wouldn't you know it, the bus actually bypassed the centre of the city instead zipping through some run-down streets alongside the railway.

Jetstar have since fitted-out their fleet with electronics that would have allowed us to land in Queenstown. But, given their recent bad press on cancelled flights, it says much for the power of the dollar - the X-factor - that we opted for Jetstar again.