The man, arrested in London, was detained on suspicion of preparing terrorist acts under section 5 of the Terrorism Act 2006. He has now been released on bail as counter-terrorism police continue an investigation that officials say includes "possible foreign state involvement" in the suspected plot.
Prime Minister Andy Burnham said there were "strong indications" that Iran was involved in the incident near the Gloucestershire military base. The man is the sixth person detained in connection with the alleged plot.
The release means the suspect, who has not been charged, remains subject to the investigation while officers pursue their inquiries into the incident at RAF Fairford, a base in Gloucestershire. Details of the alleged plot itself remain limited, and no further information has been released about the circumstances of the arrests or the evidence gathered so far.