The country's largest airline IndiGo on Friday saw its profit after tax slide 18.3 per cent to Rs 2,448.8 crore in the three months ended December 2024 due to foreign exchange loss even as revenue jumped on higher capacity and passenger traffic.The carrier, which had a fleet of 437 planes at the end of December, is planning to induct wet leased planes for long range flights and expects the number of grounded aircraft to come down to 40s by the start of next financial year from the current level of 60s.