Interlining - Costs

Hi all

I'm sometimes really wondering about costs/required personnel of interlining contracts. There are some small airlines with only a couple of aircrafts where I have to pay a lot for the contract, on the other side for the contract with some of the other big airlines I have to pay < 1000AS$ per week.

Could it be that the costs of the IL are spread depending on the size of the airline? Isn't it a problem that it is usually not worth for a big airline to start an IL contract with a small one as it costs a lot only for a hand full of new passengers? And why is it so cheap as big airline to have and IL with another big airline?

I believe IL costs increase with airline size, thus you pay more for IL with a large carrier. Since it makes no difference how many flights between the two airlines actually enable connections, IL with large carrier may be unattractive for a small airline. I usually only IL with larger carriers if our flights connect at more than one airport.

Trust me it is not cheap large airline to large airline :)