United Airlines is unveiling two new mainline jets that are the largest in its class. The airline announced it's acquiring 270 Boeing and Airbus jets with plans to carry more travelers. The airline said it intends to add roomier seats and seatback entertainment. An executive for United says the purchase of the new aircrafts is a landmark moment that symbolizes an improved outlook for future travel. The five-year expansion plan is also expected to add thousands of jobs at the airline's hubs around the country, including 3,000 jobs in Houston.