The measure affects flights using Avro aircraft. Brussels Airlines has 28 such aircraft in its fleet.
The Avros will now fly at a speed of 0.69 mach instead of the usual 0.70 mach.
Flights should only arrive one or two minutes later than at present, but realise a considerable cost-saving.
In all the saving on Brussels Airlines' fuel bill should amount to 1.1 million euros.
Rising fuel prices are pushing up airline costs.
The Dutch airline KLM increased its fuel surcharge this week.
Brussels Airlines is levying a 25 euro surcharge on European flights, 77 euros on long haul flights.
Flights should only arrive one or two minutes later than at present, but realise a considerable cost-saving.
In all the saving on Brussels Airlines' fuel bill should amount to 1.1 million euros.
Rising fuel prices are pushing up airline costs.
The Dutch airline KLM increased its fuel surcharge this week.
Brussels Airlines is levying a 25 euro surcharge on European flights, 77 euros on long haul flights.
