Protesters wanted to stop people "being killed or harmed" by securing themselves around a deportation plane preparing for take-off, a court heard.
The jet had been chartered by the Home Office to take people from UK detention centres to Africa on 28 March 2017.
Fifteen activists made their way onto the runway at Stansted Airport before locking themselves together with pipes and foam, Chelmsford Crown Court heard.
One said he feared for the safety of those due to be deported.
Benjamin Smoke, 27, of Rowley Gardens, London, said the group had been told there were three deportees due to be on the flight who were in danger if they were returned to Nigeria and Ghana.
Mr Stoke said he feared for the safety of a woman who had said her husband had told her he would kill her if she came home.
He said: "I was fighting to stop the plane deporting people to a place where they would be at risk of being killed or seriously harmed."
The defendants have pleaded not guilty to a single charge of intentional disruption of services at an aerodrome.
- Helen Brewer, 28, of Ferne Park Road, London
- Lyndsay Burtonshaw, 28, of Upper Lewes Road, Brighton
- Nathan Clack, 30, of Ferne Park Road, London
- Laura Clayson, 28, of Brownswood Road, London
- Melanie Evans, 35, of Vicarage Road, London
- Joseph McGahan, 35, of Path Hill Farm, Reading
- Benjamin Smoke, 27, of Rowley Gardens, London
- Jyotsna Ram, 33, of Brownswood Road, London
- Nicholas Sigsworth, 29, of Ferne Park Road, London
- Melanie Strickland, 35, of Borwick Avenue, London
- Alistair Tamlit, 30, of Brownswood Road, London
- Edward Thacker, 29, of Ferne Park Road, London
- Emma Hughes, 38, of Vicarage Road, London
- May McKeith, 33, of Vicarage Road, London
- Ruth Potts, 44, of Ashton Gate Terrace, Bristol.
The trial continues.