Jet Airways' pilots' union has appealed to India's top court to direct State Bank Of India (SBI) to release interim funding to try to revive the grounded airline, according to a court filing made on Tuesday which was reviewed by Reuters.

Jet halted all flight operations indefinitely on April 17 after its lenders rejected its plea for emergency funds, potentially the end of the line for what was once India's largest private airline.

The debt-laden airline has struggled to compete with low-cost carriers like IndiGo and SpiceJet that now dominate Indian skies, and its mounting losses forced it to ground its planes.

The National Aviator's Guild said in its petition that SBI's decision to not give the interim funding of 15 billion rupees ($216 million), after agreeing to it in March as part a resolution plan, has resulted in the airline being grounded and has impacted the livelihood of Jet's 22,000 employees.

This ‘singular decision’ by SBI was responsible for the operations of Jet Airways coming to a stop and ‘substantial de-valuation/depreciation in the value of Jet’, the union said in the court filing.

SBI, as part of the resolution plan, has also invited bids from potential investor to take a stake in Jet. So far no bidders have publicly shown interest and the final bids are expected to be submitted by May 10.

There was no immediate comment from SBI.

Without the emergency funds Jet was unable to pay rentals on its leased aircraft, forcing lessors to take back planes.

Its slots have been temporarily re-allocated to other airlines and some of its pilots and other employees who have not been paid in months have taken up jobs elsewhere.

The union has asked the Supreme Court to direct the civil aviation ministry and aviation regulator to decline any further de-registration requests for Jet's leased aircraft and not to reassign its slots to other airlines permanently, according to the filing.

Allocation of Jet's slots, allotment of its seats under the international bilateral agreement with other airlines and handing over its de-registered aircraft to other carriers without following due process has ‘further devalued the worth of Jet Airways’, the union said in its petition.

‘The consequence is that there is hardly any likelihood of some serious buyer for the airline,’ the pilots' union said in the petition, urging the court to act swiftly.