The passenger figures Qantas released to the stock exchange yesterday weren't flash - but the unannounced financial reality was much, much worse.

While Qantas told the ASX its May Qantas International and Jetstar International revenue seat factors were up 4 and 4.8 percentage points respectively, it didn't say that its yield on the combined international business had collapsed by 25 per cent.

The yield - the average price paid by the distance flown - points to the extent of fare discounting rampant on international routes and provides a more meaningful indication of how the bottom line is faring.

Qantas announces financial-year-to-date yield numbers, but not a monthly breakdown. For the 11 months to May, international yield is down just 2.6 per cent and total domestic yield is off 4.7 per cent.

But airline-watchers at the Centre for Asia Pacific Aviation calculate from the running year-to-date numbers that international yield for May plunged 24.6 per cent and domestic yields fell 8.7 per cent. Those numbers were confirmed for BusinessDay by another aviation analyst.

"Last week's B787 deferments and cancellations are understandable given the cash strain the airline is under with yield numbers like this and the likely future capacity profile the airline will need to adopt to pull out of its current nosedive," CAPA reports.

"Ongoing economic turmoil and increasing capacity in many of its core markets, particularly the incursions by Middle East carriers internationally and Virgin Blue/Tiger Airways domestic, make for a bleak near term outlook for Qantas."

Yesterday's announcement to the ASX showed Qantas' international passenger numbers down 13.5 per cent to 527,000 while Jetstar international passengers jumped 51 per cent to 205,000 as Qantas switches more routes to its low cost carrier.

But the yield numbers indicate both cause and effect for the move to the LCC, even as the company cuts total capacity, down-sizing its operations to fit the reduced and more competitive market.

While total group revenue passenger kilometres - backsides on seats - were down 3.9 per cent, total available seat kilometres - capacity - had been cut by 8.3 per cent, allowing the company to post an almost 5 per cent rise in its revenue seat factor.

But that rise means little when the amount passengers are paying for the seats has crashed.

As a 1970s professor of statistics allegedly used to tell his class: "Statistics are like a bikini, ladies and gentlemen. What is revealed is suggestive, but what is concealed is vital."

And the discounting continues. Qantas today announced 30 per cent off its business class fares across the continent to Perth - a route and seating class that the commodities bubble had made extremely profitable and busy.

(Qantas was asked to comment on May's fall in yield. A spokesperson said monthly yield was not an ASX reporting requirement. Further comment was not received by publication time.)

Michael Pascoe is a BusinessDay contributing editor.