https://forums.operationsports.com/forums/forum/football/madden-nfl-football/madden-nfl-football-online/tfl/26823086-what-is-the-best-time-to-buy-united-airlines-tickets
Travellers have the alternative to check in via airport as well. Those who do not want to check in online, can check in at the airport. At the airport, the travellers can either check in by visiting the Lufthansa check in desks or by using the self check in machines available at the airport