While Rainey has said the 777-300ER interests United, he noted Monday that the aircraft could be a quick fix in markets where United needs additional seats to satisfy demand so customers are not forced to book on United’s competitors. United currently is considering whether to swap Boeing 787 Dreamliners it has on order for its first 777-300ER aircraft, which can fit more seats. The swap would be a victory for Boeing, which has long insisted it can sell the 100 777-300ERs it plans to produce annually before it shifts toward building the 777X, starting in 2017.