Emirates has ordered 50 wide-body 777 jetliners, a deal valued at $18 billion or more, at the Dubai Air Show. It’s the largest airplane order in the long history of Boeing and a huge boost to the air show, already the largest industry event in the Middle East. More big announcements from other airlines might follow at the event, which runs until November 17. Meanwhile airlines based in Europe and other markets can only watch nervously as oil-money-backed Emirates and other Gulf airlines continue to expand in reach and scale, reshaping the world aviation map and putting the Middle East ever more at the center with planes that, like the 777, can fly long distances with relative fuel-efficiency.