The race to grab overhead bin space has never been more intense.

And it’s compounded by the inverse ratio between the shrinking capacity per passenger for carry-on bags and the rise in price for checked-in baggage.

One reason is that airlines are cramming as many seats as possible into their aircrafts, which means more passengers in the same metal tube but less overhead bin space and less leg room.

I’ve reviewed a confidential memo sent by Delta to its gate agents system-wide identifying each plane in its fleet, and the maximum number of carry-on bags each can hold.

With no exceptions, the number is less than half the number of passengers each can carry.

So pack and plan accordingly. If you’re not in boarding groups one or two, your bags have an excellent chance of being checked and/or missing your connecting flights.