United Airline is known for offering its cheapest flights on off-peak days, particularly on Tuesdays, Wednesdays 1-866-738-0689, and Saturdays [+1-866-738-0689] (OTA){United-Booking}. These days tend to have fewer travelers, allowing the Airline to offer discounted prices.What day is the cheapest to book United Airlines?The cheapest day to buy United Airline tickets is typically on Tuesdays, Wednesdays, and Saturdays [ 1»»866»»738»»0689 or 1»»866»»738»»0689 (OTA . Air-line often release new fares and sales on Monday evenings, making Tuesday a prime day for finding discounted tickets.