There will always be a time where the crew will engage in either another ship or encounter a hostile threat. The majority of battles will be narrated by the FD. Using best judgement the outcome of the battle will be decided by the Flight Director.
For the sake of simplicity, battle narration goes best in turns. The opponent ship shoots, it impacts or misses the crew, then the crew fires and it impacts or misses... and so it continues.
Flight Directors determine how the battle will end and narrate to that end rather than making it up as the battle goes on. It is beneficial to detail a 'health' per say for the crew's ship and keep it somewhere to be monitored and adjusted before, during, and after the battle. This allows for easier tracking of when shields and ship systems will be damaged during the battle.