Hi All,

Today, I was upgraded on an Air China flight to Business Class, from Economy. Flight was Taipei to Shanghai. It was on a paid Economy class flight, low fare may I add with cancellation/rescheduling restrictions. This was only the second time that I have been upgraded (the first, coincidentally being on another Air China flight from Shanghai to Dubai). I am Kris Flyer Silver Elite (not Gold).

This makes me wonder what is the criteria that airlines consider when upgrading passengers for free?

For example:

- First time flying with a particular airline.
- Level on Star Alliance program.
- Amount of travel with the airline in Economy class (to get a taste for a carrier's business class)
- Good manners and profile at the check-in counter.
- Pure luck.

Thanks!