Group 1 - Frontier Airlines has joined Delta Air Lines in withdrawing its full-year outlook and reducing flight capacity due to a decline in demand and an "uncertain environment" [1] - The budget airline has also revised its first-quarter outlook, projecting a revenue growth of approximately 5% with capacity also increasing by 5% compared to the previous year [1] Group 2 - Revenue growth is expected to be lower than anticipated due to weakened demand observed in March, leading to fare discounting and promotions across the airline industry [2] - A decline in consumer confidence in March has been cited as a contributing factor to the reduced demand [2]