US planemaker Boeing and European arch-rival Airbus revealed multi-billion-dollar orders for their planes here on Tuesday as the Farnborough airshow took off from a slow start. Boeing unveiled a commitment to sell 100 upgraded single-aisle 737 planes worth a combined $9.2 billion (7.5 billion euros) at list prices to US leasing group GECAS. Though still to be finalised, the deal builds on Boeing\'s announcement Monday -- the first day of the Farnborough show -- of a contract worth $7.2 billion for 75 of its short-haul 737 MAX jets with US group Air Lease Corporation. Airbus also came good on Tuesday, surprisingly announcing that Hong Kong airline Cathay Pacific had ordered 10 of its future long-haul A350 planes worth $3.2 billion. Cathay also agreed to convert 16 of its existing orders for the A350-900 to the larger A350-1000, earning Airbus another $1.0 billion. The deal was a boost for Airbus, a day after it revealed only a tame order for four of its upcoming single-aisle neo passenger planes -- a rival to Boeing\'s MAX series -- to Arkia Israel Airlines for a combined $453 million. Also on Monday, Airbus chief executive Fabrice Bregier conceded that there could be new delays to the delivery of its A350 plane which is due to enter service in mid-2014. Speaking of the Cathay deal, Bregier said: \"This announcement from one of the world\'s most highly respected airlines is a clear endorsement of the unbeatable operating economics offered by the A350-1000. \"The A350-1000 will be a game changer in the 350-seat category, offering outstanding payload-range capability and a 25 percent reduction in fuel burn.\" The A350 is a response to Boeing\'s 787 Dreamliner, which is now flying after long technical delays. The real battle though at the latest Farnborough show -- a key biennial event in the aviation sector calendar -- was for orders of short-haul aircraft. Boeing is seeking to steal a march over France-based Airbus, which has enjoyed great success in the single-aisle sector with firm orders for its A320neo. The US company on Tuesday revealed a commitment by GE Capital Aviation Services (GECAS), the commercial aircraft leasing and financing arm of General Electric, to purchase 75 737 MAX 8s and 25 Next-Generation 737-800s. \"Boeing looks forward to working with GECAS to finalise the details of the agreement, at which time the airplanes will be posted to the Boeing Orders & Deliveries website as a firm order,\" it said. Boeing\'s 737 MAX is an upgraded and more fuel-efficient version of the 737, the world\'s best-selling commercial airplane. The first 737 MAX is scheduled to be delivered in 2017, two years after the neo, which has been billed as a more fuel-efficient A320 thanks to engine upgrades. The 737-800 is meanwhile already in service. Despite Boeing\'s success at Farnborough regarding its 737 MAX planes, the US group is playing catch-up with Airbus in the market for upgraded single-aisle planes after the European rival enjoyed big success at last year\'s Paris airshow. Elsewhere on Tuesday, Canadian aircraft manufacturer Bombardier said it had signed a letter of intent with Latvia\'s airBaltic for up to 20 of its future CSeries planes looking to compete with the neo and MAX. Bombardier said the airBaltic deal for its CS300 planes, which are due to enter service in late 2013, could be worth up to US$1.57 billion.