Commercial aviation is in just the beginning of its current crisis. During such time employees should expect to take employment condition hits, like everybody else in the world.
I cannot see why sectorial employee contracts need to have expiration dates and therefore be renegotiated. This creates instability, permanently inherent in the British labor market, adversely affecting the British economy, or anywhere else this pattern exists. Moreover, emplyee unions cause more harm than good to the people they represent and thereby to the whole society.
You have a marketable skill- sell your ability, work properly and get rewarded. I worked as freelance flight program manager, did a good job and for a one year effort payable by 12 monthly salaries, I got three additional equal payments as bonus, not included in my contract. Why? because my management did miracles to the boss's bottom line as well as his long term position in that specific market. He knew how to appreciate it. Unions? a thing of the not so successful past. Proper performance-based remuneration should replace it.