Cathay Pacific says it would not be giving a lifetime of free air travel to a baby who was born on one of its flights this week.

The baby boy entered the world six weeks early while his mother was onboard a flight between Hong Kong and the southern Australian city of Adelaide.

The plane was forced to make an unscheduled landing in Darwin.

There has been speculation since the birth that it is protocol for the baby to be given free air travel with the company.

But David Bell from Cathay Pacific says it is an old-wives tale.

"Origination goes back many years in the early days of flying when I think there were a couple of American airlines that did in fact give kids that were born on their flights free life passes but nowadays unfortunately it's totally impractical with just the high volume of travel and re the availability of seats."

Produced by Radio Australia and Australia Network