This summer passengers flying Air France between London Heathrow and Paris CDG might well find themselves booked on a commuter plane.

Normally Air France would roster one of its two-class mainline aircraft for such a key route.  After all Air France wants to create a good impression for those travellers wishing to connect to its global network at Paris CDG.

But instead of using a large A320 Air France will hand over one daily flight to commuter subsidiary Hop!

The flights in question are already available for booking via Air France’s website. They are AF1181 London-Paris 1945-2200 and AF1080 1815-1835

From end March a smaller one-class 100-seat Embraer 190 is being rostered for both flights. There will be no business class.

So why would Air France cut capacity during this busy travel season?

I suspect Air France is practising an aviation wheeze known as ‘slot sitting.’

As we all know Heathrow is a very congested airport. Airlines can lose slots if they fail to use them for one reason or another. See “Use it or lose it” from The Economist.

Logically if demand is weak one would expect carriers to consolidate.  They would operate fewer flights using larger aircraft. This in turn would free up slots for newcomers.

But Air France is a sixth-freedom carrier. It needs a range of flights to provide customers with optimum connections.

Partner KLM (probably Europe’s leading sixth-freedom carrier) has been slot sitting for many years at Heathrow.

Check and you will see that several of its Heathrow-Amsterdam flights are operated by commuter aircraft sourced from its Cityhopper division.

And indeed our Tom Otley found himself on a smallish (by Heathrow standards) Fokker 70 when, six years ago, he flew on an Amsterdam-London Heathrow service with KLM.

KLM’s point-to-point traffic at Heathrow has declined over the years. A good number of passengers have defected to the carrier’s other airports notably London City, Luton, Stansted and Gatwick.

By retaining slots KLM also profits by leasing one or more of its Heathrow landing rights to other carriers.

A good example being Nairobi-based Kenya Airways. It now leases its Heathrow slot from KLM having sold the one it owned outright to Oman Air in a bid to raise much needed cash.  (Kenya Airways raised US$75 million from the sale)

So in conclusion if flying Air France this summer bear in mind that not all its Heathrow flights will be operated by its mainline division.