Emirates, the world’s biggest long-haul airline, will form a partnership with low-cost sister carrier FlyDubai aimed at allowing the companies to feed passengers onto each other’s flights. The deal will include network collaboration and coordinated scheduling at Dubai International Airport, where both airlines are based, Emirates said in a statement Monday. It will be rolled out from the fourth quarter starting with enhanced code-sharing arrangements. Dubai has been looking at placing the two government-owned carriers under a single structure for several months. The move means FlyDubai’s regional flights will help fill Emirates jets, while the discount operator gets access to a global network of 157 destinations. New city pairs are set to be opened up and duplicated routes eliminated, while frequent-flyer programs may be aligned. The partnership unites two complementary models and will unlock “immense value,” said Sheikh Ahmed bin Saeed Al Maktoum, chairman and chief executive officer of Emirates Group and chairman of FlyDubai. The airlines will continue to be managed independently, he said. Emirates suffered a 70 percent drop in profit in the year ended March 31 as the low price of crude clipped growth in oil-based Persian Gulf economies, terrorist attacks hurt demand for travel and the company faced U.S.-imposed travel restrictions. Tim Clark, the carrier’s president, has also expressed concern about the threat from discount long-haul rivals in Asia and Europe.