Beyond a myriad of domestic issues, the next leaders of India's top two airlines will need to mitigate the effects of the Middle East conflict, which has sent fuel prices soaring and forced lengthy detours on some routes.
New Delhi announced last week it would cap monthly increases in aviation turbine fuel prices for domestic flights at 25% to help shield passengers from sudden fare hikes.
Meanwhile, the deterioration in India's relations with Pakistan has closed Pakistan's airspace to Indian airlines as well, significantly increasing costs and flight times.
Airlines across the region have put in place contingency plans including trimming schedules and carrying additional fuel. Read here to understand some of the steps being taken.
Higher fuel costs, depreciation of the Indian rupee and lower international operations will hurt IndiGo's earnings for the financial year that began April 1, analysts at Mumbai-based brokerage Motilal Oswal said, as they cut their profit estimate for the airline by 15%.
IndiGo's global expansion goals
Immediate issues aside, analysts see Walsh's appointment as signalling the $16 billion budget carrier's seriousness about global network expansion and strategic partnerships.
At Aer Lingus, where he started out as a cadet pilot in 1979 before becoming CEO in 2001, Walsh stabilised long-haul operations while overhauling the short-haul business with significant cost cuts - earning him the nickname "Slasher".
IndiGo dominates the domestic market with a nearly two-thirds share, and currently flies to more than 40 international destinations.
It's set to take delivery in the next few years of longer-distance Airbus A321XLR and A350 jets.
Walsh doesn't take over until August, after his term ends as director general of the International Air Transport Association (IATA).
Until then, co-founder Rahul Bhatia remains in charge as interim CEO.