Air Coase

No matter how much the screaming baby on an airplane annoys you, it really isn't imposing a Pareto-relevant externality. Recall that a Pareto-relevant externality is one where there are gains from trade that fail to obtain. The airline here is residual claimant: if it could earn more by having baby-free flights, or by restricting children to some segments of the airplane, it would do it. Airlines aren't going to throw money away by failing to implement baby-abatement policies if implementing them would earn them higher profits. Absence of baby-abatement airline policies is then evidence that inconvenience imposed on parents by a change in policy outweighs the inconvenience babies impose on other fliers.

Turns out there are two airlines that cater to demand for kid abatement.

Malaysia's two main airline groups have provided a way through the morass by creating kids-free zones in their biggest planes on long-haul routes.

Malaysia Airlines went first in 2011 when it banned kids in first class on its 747s and extended the policy in 2012 when it introduced the superjumbo A380 on twice-daily flights from Kuala Lumpur to London.

The A380 kids policy applies only to the upper deck's tiny economy section of 70 seats behind the 66 seats in business class. However, it's not an outright ban: the airline still has bassinets in the upper deck economy section and will allow kids if there's a kids overflow from the lower deck.

In any case, there are still baby bassinets on the upper deck in business class, so MAS is simply trying to make the upper deck quieter than it otherwise might be.

AirAsia X, which flies from Kuala Lumpur to the Gold Coast, Sydney, Melbourne and Perth and now has an interlocking shareholding with Malaysia Airlines, this month also introduced kids-free "quiet zones" in the forward section of its economy class, where kids under 12 aren't allowed. If you want a seat in the quiet zone, it's offered as an optional extra for which a surcharge applies.

"The airline is not banning kids from travelling, but instead, is enhancing the array of product offerings on board to suit its guests individual needs and preferences," says AirAsia X chief executive Azran Osman-Rani.

I love it when a Coasean-bargaining plan comes together.

There are situations where there are real Pareto-relevant costs imposed on you by other fliers despite the airline being residual claimant: government policy in some countries makes it illegal for airlines to charge heavy fliers more, or to require them to take an extra seat. Governments thereby create market failures by externalising the internality.