What's the meanig of this sentence :The carriers also enjoyed higher load factors, which measure the proportion of available seat miles occupied by paying passengers. in the following context.

Passenger traffic up at Air Canada, WestJet

Last Updated Thu, 07 Jul 2005 16:49:05 EDT

 

 

Passenger traffic increased in June over the same month a year ago at both Air Canada and WestJet.

Figures released by the airlines Thursday show revenue passenger miles, which measures the number of paying passengers multiplied by distance flown, grew by 7.3 per cent to 3.99 billion at Air Canada and by 22.4 per cent to 615.4 million at WestJet.

Both airlines also increased passenger capacity over June 2004.

Available seat miles, which calculates the number of seats available for sale multiplied by distance flown, rose 4.7 per cent to 4.9 billion at Air Canada and by 19.8 per cent to 837.8 million at WestJet.

The carriers also enjoyed higher load factors, which measure the proportion of available seat miles occupied by paying passengers.

Air Canada's load factor increased by 1.9 percentage points to 81.3 per cent – the highest ever for June – while WestJet's rose by 1.6 percentage points to 73.5 per cent.

Air Canada's regional airline subsidiary, Jazz, also posted higher figures in all three categories.

Well, the sentence itself is basically a definition.  That is, the definition of "load factor".  I'm not sure how to phrase it better than it's already written, but I'll try. The very basic meaning is that the airlines, Air Canada and WestJet, are transporting more passengers.  They measure this by calculating "load factors".  According to the very sentence you've selected, a "load factor" is the percentage of "available seat miles" that are actually used by passengers.  In turn, this piece states that "available seat miles" are simply "the number of seat available for sale multiplied by [the] distance flown."

So, mathematically...  (seats available for sale)(distance flown) = available seat miles

(amount of seats sold) / (available seat miles) = load factor