New Delhi, April 16 -- With a market cap of $23.45 billion, Indigo just became the world's most valuable airline. Let that sink in. This is a company that didn't exist 20 years ago, in a sector that was thrown open to the private sector just 10 years before that. Sure, it is a beneficiary of the changing dynamics of the global travel industry in which South Asia and India are the world's fastest-growing commercial aviation markets. Aircraft maker Boeing has forecast that India and South Asia's commercial airplane fleet will grow nearly four-fold over the next 20 years, with the region's air traffic set to expand more than 7% annually through 2043.

That figures. Two years ago, IndiGo and Air India placed orders for hundreds of jets in wha...