* Air France-KLM abandons profit hopes for 2008/09
* Shares in Europe's largest airline fall 9 percent
* Warning highlights trade slump ahead of G20 summit
* Engine maker Pratt & Whitney braces for job cuts
* Brazil planemaker Embraer unveils big drop in profits
(Adds further share price fall, weaker U.S. airlines)
By Tim Hepher
PARIS, March 27 (Reuters) - Shares in Europe's largest airline fell sharply on Friday after Air France-KLM ditched any hopes of making a full-year profit and warned of "unprecedented difficulty" as the global crisis strangles trade.
The group said late on Thursday it expected an operating loss of 200 million euros ($268.1 million) in its financial year to March 31, compared with a profit of over 100 million expected by the market, sending its shares down as much as 9.1 percent.
It predicted a further operating loss in 2009/10.
The warning followed on the heels of weak traffic figures from international airlines body IATA on Thursday and fuelled evidence that economic woes have continued unabated into March, as G20 leaders prepare moves to unfreeze global trade next week.
It also contrasted with the same airline's predictions of a profit just six weeks ago, proving how many are struggling to make forecasts as their visibility over forward bookings falls.
Although most airlines are suffering, Air France-KLM is typical of network carriers taking the brunt of the pain because they depend on commerce and industry for traffic as much as tourism, the stamping ground of low-cost rivals.
"The downturn is global and the downturn is most exposed to falls in cargo and premium (business and first class) traffic," said aviation analyst Stephen Furlong at Dublin brokerage Davy.
Created by a Franco-Dutch merger in 2004, Air France-KLM says it is picking up market share thanks to a powerful twin hub at Paris and Amsterdam. But it has also been hit by outdated fuel price hedges taken out when oil prices were high.
IATA had said on Thursday passenger traffic fell 10 percent in February and international air cargo traffic fell 22.1 percent, echoing two previous months of bad data
And Air France-KLM said the first weeks of March, usually one of the busier months, brought no change in trends.
It highlighted a "significant" drop in unit revenues, "notably as a result of the decline in business travel and international trade".
LOW-COST ADVANTAGE
Air France-KLM closed down 7.8 percent at a three-week low of 6.58 euros in a market down 1 percent. In the United States, top airlines lost $1 billion in value in early trading.
Rival British Airways, which although heavily exposed to plunging transatlantic business travel is seen as less vulnerable than Air France-KLM's globally balanced network to trends in cargo, saw its shares down just 0.4 percent.
Europe's leading low-cost airlines Ryanair and EasyJet managed increases of about 1 percent.
Traditional carriers with higher fixed costs are more prone to see their core profitability kicked lower when revenues fall -- a risk-inducing financial effect known as operating leverage.
And while many people remain reluctant to sacrifice a family holiday, industrial warehouses are seen at a near standstill.
"Low-cost airlines will prove to be more defensive because they are not exposed to premium travel or cargo," said Exane BNP Paribas airlines analyst Geoff Van Klaveren in London.
Economists say a shortage of trade financing has contributed to the sharp drop in global trade which is penalising airlines and shippers. Almost half of international freight goes by air.
Britain said on Thursday it would ask G20 leaders to back a $100 billion expansion of trade finance to reverse a fall in exports at a summit it is hosting next week.
Airlines have cut tens of thousands of jobs and over 40 have been grounded in the past 18 months, crippled first by oil, then by a slump in passenger demand and now a collapse in cargo.
The downturn drew a fresh warning overnight that job pressures could feed through to aerospace manufacturers.
The head of United Technologies Corp jet engine unit Pratt & Whitney told Reuters in an interview it expected to make "significant" additional layoffs this year.
Meanwhile Brazilian jetmaker Embraer posted a 44 percent drop in fourth-quarter profits on Friday on derivative losses and slower sales. * For more on the economic crisis please click on (Additional reporting by Blaise Robinson, Scott Malone, Adrian Croft; Editing by Greg Mahlich) ($1=.7460 euros) ((+331 4949 5452 paris.equities@reuters.com))