Fleet Operational Sea Training (FOST) is a Royal Navy training organisation. Up until May 2020, the Flag Officer Sea Training led a training organisation responsible for ensuring that Royal Navy and Royal Fleet Auxiliary vessels were fit to join the operational fleet. A Freedom of Information answer states that as of 1 May 2020, the position of Flag Officer Sea Training will no longer exist and the position taken up by a Commodore, in the appointment of Commander Fleet Operational Sea Training.