Fixed term contract employees

Respected experts, I work for reputed airline which had a base in India. Permanent employees were recruited until 2006. From 2007 January they started recruiting employees only on fixed term contract (FTC for 1 year). They have continuously renewed these contracts for the last 10 years. Both permanent and FTC employees do the same job with same numbers of hours and benefits. Except that FTC employees are in constant fear of losing their job at the end of contract without reason. Due to which they have not been able to join Union which has only permanent employees. Currently company says that they are going to change terms of employment with reduction in salary. Permanent employees are fighting via Union, but FTC have to accept it without negotiation. Is it legal to have continuos renewal of FTC ? Is there a way that we can negotiate too after being employed for 10 years? Can we have 2 sets of employees in the same company, doing the same job but on different terms of work condition and salaries? Your opinions and suggestions are highly appreciated.