Boeing signed a $27 billion agreement on the second to last day of the Dubai Airshow with UAE-based flydubai for 225 of the manufacturer’s 737 Max narrowbody airliners. Airbus countered with the announcement of a memorandum of understanding (MoU) with private equity firm Indigo Partners for 430 A320neo narrowbodies, destined for four airlines. That deal, if ultimately completed, would come to close to $50 billion at list prices.

The Boeing deal is defined as a “commitment” for 175 aircraft, with purchase rights for 50 more. Fifty of the first 175 aircraft will be 737 Max 10s, the newest and largest version of the 737 family. The balance of the initial flydubai order will consist of Max 8s and Max 9s. The deal represents the largest narrowbody order ever placed by a Middle East carrier, according to Boeing.

His Highness Sheikh Ahmed bin Saeed Al Maktoum, chairman of flydubai, said, Boeing’s 737 series has “provided the foundation for the success of our business model, providing us with the operational flexibility and range to build a network of 95 destinations in 44 countries. Understanding the demand for travel across our network, our innovative approach to our cabin design and developing a product unique to our market has allowed us to exceed our passengers’ expectations in their flying experience.”

The 430-aircraft Airbus MoU with Indigo, which sets up low-cost airlines, would be allocated among the firm’s four carriers: U.S.-based Frontier Airlines; JetSmart of Chile; Mexico’s Volaris; and Wizz Air of Hungary. The deal consists of 273 A320neos and 157 A321neos. Indigo-controlled airlines have already placed orders for 420 A320-family narrowbodies.

John Leahy, Airbus COO customers, said, “Indigo Partners has been a tremendous customer and supporter of the Airbus single-aisle fleet for many years. An order for 430 aircraft is remarkable, but it’s particularly gratifying to all of us at Airbus when it comes from a group of airline professionals who know our products as well as the folks at Indigo Partners do.”