Let’s think more about the hints from Air New Zealand about opportunities to put economy seats together to make a ‘sleeper’.

What happens when there are lots of empty seats on a particular flight?

Will the carrier try to rope them off to stop passengers spreading out into the empty seats for free, and leave the customers fuming at being confined to their booked seat?

Or put guard dogs in them?

The Air NZ initiative sounds very welcome in a situation where flights are usually nearly full.

But I’ve noticed recent flights taken by self and family where despite the high loads it was possible to move to a more comfortable seat after take off to one beside an empty seat, or even into an exit or bulkhead row seat, with no extra charge.

And while Qantas and Singapore Airlines are among long haul carriers offering the best economy class seats for a surcharge of as much as $160 per sector, there has been some negative feedback from those who notice others using them for free, or having paid for one, find themselves even closer to the crying baby.

The business case by Air New Zealand seems to be based on the expectation that in typically near full cabins they will be able to sell at check in most of the remaining empty seats for around $150 to exploit a new seat design that will easily allow two of them to be combined into a more comfortable space.

Air NZ says it won’t reveal the precise details until next April and the product will arrive with the introduction of the –300ER version of the 777 into its fleet late in 2010.

Maybe the plan will be to allow one seat to be folded back onto one behind it to create a ‘couchette’ like sleeping space.

This solution was used for a while in the 90s by SAS in business class in its 767s, where for a surcharge of around $500 you could stretch out in its otherwise rather tight configuration in its cabin in the era before true sleeper seats were widely offered. The option was said to have been a commercial failure, and was dropped for the common place sleeper-sloper configuration when the Boeings were replaced by Airbuses.

Or maybe there is much more to the Air NZ plan, and it has gone for the dreadful 10 across cram configuration in the 777 economy cabins and will offer the seats unsold at check in as a comfort upgrade.

Regular Air NZ customers will be scratching their heads over this, as it already has a very good premium economy product, which costs considerably more than an extra $150 per sector, but doesn’t offer any serious ‘sleeper’ experience.

The hint of an economy sleeper arrangement implies that Air NZ will have three different types of economy in its next 777s, standard, upgraded sleeper economy. and a premium economy which is not truly a sleeper, as well as business class.

Or maybe Air NZ is dropping premium economy. In the absence of real details there are various possibilities, but all pointing to an awful lot of class divisions in a carrier with only medium sized jets.

Whatever Air New Zealand does will be studied closely by Qantas and V Australia, with the former planning to expand its premium economy cabins and the latter already dropping hints about fitting more economy seats in its 777-300ERs.