WHEN people consider which manufacturer will dominate the skies in the age of wide-bodied aircraft, they usually think of Boeing and its 777 or Airbus with its A330. But there is another, equally fierce, battle being waged: between the makers of the engines which are used on the new generation of aircraft. The battle pits three players - General Electric (GE), Pratt and Whitney (P&W) and Rolls-Royce International (R-RI) - all of whom are engaged in a do or die competition to see which can persuade aircraft manufacturers to certify their engines. The battle is so intense that engine manufacturers are spending millions of dollars helping the aircraft manufacturers to certify their engines. According to Geoff Landamore, regional executive with R-RI, the battle for market share is all the more precarious because manufacturers no longer have a strong loyalty to a favoured engine-maker. ''In the past, airlines tended to be dedicated to one engine,'' said Mr Landamore. In the early days of aviation, it was common to see just one type of engine on a given make of aircraft. In the '50s, the Boeing 707 would use P&W engines and nothing else. But more recently, as the aviation industry has become more sophisticated, it has become possible to outfit the same make of aircraft with more than one type of engine. Today different engine designs and makes can be found on both the Airbus 320 and the Boeing 767. Mr Landamore said the result has been that the monopoly that a given engine-maker enjoyed with an aircraft manufacturer was now breaking up. ''The engine manufacturers are looking to break into one another's markets.'' The see-saw battle for market share is already taking place for new generation aircraft like the Boeing 777 and the new Airbus. One of R-RI's success stories was to persuade Thai International to switch from using only GE engines to using R-RI engines as well. Mr Landamore said the company had fought back from a position where it controlled just eight per cent of the engine market in the early '80s. Last year it took 25 per cent of the market and was hoping to account for 30 per cent in the near future. ''In the '80s, Pratt and Whitney dominated the market and Rolls-Royce was in third place,'' he said. ''But we have improved significantly. We have come out with a much broader selection of products.'' Part of R-RI's continued success will no doubt involve more orders from China. The company has had an office in Beijing since the '70s. That has not necessarily translated into a flood of orders. ''The United States got in there early with their Pratt and Whitney and they got a strong relationship going with the Chinese,'' Mr Landamore said. But he added that airlines might switch to R-RI if the company could come up with something significantly different to what was now on offer.