He takes over from Hameed Ali, who will join the airline's board. Jet Airways' chairman Naresh Goyal's wife Anita, too, will join the board.
Karnik has worked in senior roles in marketing, strategic planning and finance departments of North West, Continental and Delta Airlines and was president and CEO of Global Aero Logistics, the largest provider of private air charter service to US military.
Before joining Jet Airways, Karnik worked as a vice-president with consultancy firm ICF International.
A Jet Airways spokesperson was not immediately available for comment. An airline source said Karnik had been designated as COO and his appointment would be subject to home ministry's clearance.
In May, the airline had appointed Cramer Ball, a former Etihad Airways executive, as CEO.
Jet Airways expects to return to profit in the next 18 months, following implementation of a new route network and fleet strategy and cost optimisation measures.
In May this year, Jet Airways chairman Naresh Goyal had said in a statement that the airline would have to take tough decisions and follow a three-year business plan to achieve profitability.
"We need to take stringent measures to ensure our success in this challenging and competitive aviation industry.
"There can be no short-term solution.
"The changes required will take time to implement.
"Our first priority on the journey to profitability will be to establish a more solid financial foundation for this airline," Goyal had said.
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