Boeing and Emirates Airlines announced at the Dubai Air Show today the airline's order for 50 Boeing 777-300ERs and options for an additional 20 aircraft. The order is valued at $18 billion, making it, by dollar value, the single largest commercial airplane order in Boeing's history.

"The 777's reliability, performance and operating economics have firmly established it as the backbone of our fleet," said His Highness Sheikh Ahmed bin Saeed Al Maktoum, chairman and chief executive of Emirates Airline and Group. Emirates' fleet of 94 Boeing 777s makes it the world's largest operator of the twin-aisle airliner. The Dubai-based airline took delivery of its first 777 in 1996.

According to Sheikh Ahmed, Emirates has "an ambitious and strategic plan to continue growing our international network and especially increasing our long-haul, non-stop routes."

The Emirates order makes 2011 the best-selling year for the 777 program, according to Boeing, bringing it to 182 aircraft. The previous record, set in 2005, was 154 aircraft.

The 777-300ER carries up to 365 passengers up to 7,930 nautical miles (14,685 kilometers).