High temperatures make air less dense, reducing engine performance and the amount of lift produced at a given speed. That generally means lower takeoff weights and longer takeoff distances are needed to produce sufficient lift.

United announced its largest-ever South Pacific schedule a few months ago. Across the Atlantic, United also has the most extensive network, 10% greater than the next American carrier.

The recent delays were driven mostly by a series of rolling storms coupled with other issues like a shortage of air traffic controllers in congested airspace around New York and other areas, derailing travel plans of thousands of customers.