As Jet Airways continues to ground aircraft and cancel significant number of flights, the airline's aircraft maintenance engineers' union wrote to the aviation regulator on Tuesday that three months of salary was overdue to them and flight safety "is at risk".

"It has been arduous for us to meet our financial requirements, result of which have adversely affected the psychological condition of Aircraft Engineers at work and therefore the safety of public transport airplanes being flown by Jet Airways across India and the world is at risk," the Jet Aircraft Engineers Welfare Association (JAMEWA) said in a letter to the Directorate General of Civil Aviation (DGCA).

The letter, which has been accessed by PTI, stated: "While the senior management is finding a resolution to be in business, we the Engineers who inspect, troubleshoot and certify the public transport airplanes for its airworthiness are in tremendous stress due to non-payment of salaries on time, since last 7 months. As of now, 3 month's salary is overdue to us."

Cash-strapped Jet Airways had on Monday said it had grounded four more planes, taking the number of aircraft that are non-operational due to non-payment of lease rentals to 41.

The JAMEWA requested the DGCA to intervene in the matter.

"Jet Airways' senior management had a series of meetings with us to resolve our overdue salaries and after much deliberation, finally released a payment schedule in Dec 2018 which would clear our dues in full, by the end of this financial year. However, it defaulted on it and our confidence in the company's commitments have shaken," it said.

"We request you to kindly intervene and direct Jet Airways to clear our outstanding dues and pay us our salaries on time in future to enable us to continue deliver safe airplanes," it added.

According to the Jet Airways' website, the airline has a fleet of 119 planes. For the past few weeks, passengers have been venting their ire on social media as the airline's flight cancellations have increased gradually due to the rising number of grounded aircraft. Grappling with financial woes, the carrier has been looking at ways to raise fresh funds.

Etihad Airport services had in a notification to its passengers on Sunday said: "Jet Airways has cancelled all their flights from Abu Dhabi with immediate effect from March 18 due to operational reasons".