JAT Tehnika mechanics work on maintening of Russian Transaero Boeing 737, in front of JAT Boeing 737-300, in technical maintenance hangar at Belgrade International airport, Thursday, Oct. 1, 2009. JAT Airways said Wednesday that all its flights have been grounded indefinitely because its maintenance company has stopped servicing its planes over unpaid bills. JAT said that none of its aircraft has taken off since Tuesday evening, when aviation maintenance company JAT Tehnika halted its work on JAT's fleet.