* Qantas says Q1 revenue down 3 pct on international fares
* H1 underlying profit seen A$800 mln - A$850 mln vs A$921 mln
* Shares bounce back from heavy fall, up 4 pct (Recasts throughout, updates shares, adds fund manager)
By Byron Kaye
SYDNEY, Oct 31 (Reuters) - Australian flagship carrier Qantas Airways Ltd QAN.AX warned on Monday that half-year profit could fall nearly a sixth, sending its shares into wild gyrations amid concerns about the effects of a price war hammering airline earnings globally.
By calling out the impact of cut-price international airfares, the so-called "Flying Kangaroo" joins Hong Kong's Cathay Pacific Airways Ltd 0293 , Dubai's Emirates Airline EMIRA.UL and Air New Zealand Ltd AIZ.AX which have complained about competition in recent weeks. warning, contained in Qantas's first ever quarterly earnings update, also underscores comments from Chief Executive Officer Alan Joyce at the company's Oct. 21 annual meeting, when he said it competed with 30 airlines on the key London-to-Australia route. will put pressure on Joyce to maximise returns from a host of new planned China-to-Australia routes, a growth strategy taken up by Qantas and smaller Australian rival Virgin Australia Holdings Ltd VAH.AX .
The company said it expected underlying profit before tax of between A$800 million ($607 million) and A$850 million for the six months to Dec. 31, 2016, compared with A$921 million for the same period a year earlier.
The update did not break out revenue from individual routes but the company said new international routes had "lowered average international unit revenue during their ramp-up phase".
Overall revenue fell 3 percent to A$3.98 billion in the three months to end-September, including a 6.9 percent decline in international revenue.
"Like most carriers globally, we are seeing international airfares below where they were 12 months ago," Joyce in a statement.
"The impact of that is tempered by the competitive advantages we've been working hard to fortify, including our strong domestic position and diversified loyalty business."
After falling 9 percent at the open, Qantas shares rebounded to be up 4 percent by mid-session as investors cheered a drop in the oil price at the weekend and the fact that the stock is already cheap compared with its peers. downside wasn't enough to justify any further fall in the share price, particularly when the oil price has come back under $50," said Bill Keenan, general manager of equities at Lonsec Stockbroking.
Qantas shares traded at a trailing price-earnings ratio of six, while regional rival Cathay Pacific traded at nine, Keenan said.
($1 = 1.3172 Australian dollars)