This week's trip behind the gates of RNAS Culdrose sees us meet a 30-year-old who is now one of the top instructors in the navy.

Lieutenant Carl Stephens has just qualified as an A2 observer instructor with 824 Naval Air Squadron in Helston - that's practically the top level of instructor and there are only a handful in the navy’s Merlin helicopter force.

The 30-year-old joined the navy at the age of 18 on stern advice from his grandfather, who had himself 30 years’ experience with the naval service.

“I remember I said to him that I wanted to fly, and he told me I’d be disowned if I ever joined the RAF,” he said jokingly.

Instead, Lt Stephens joined the Royal Navy’s Fleet Air Arm. After six months on deployment in Singapore, he completed his training at Culdrose and joined the frontline helicopter squadrons, which included serving on various ships including the old carrier HMS Illustrious.

He then trained to become an instructor, so that he could teach the next generation of aircrew in the art of being an observer.

So, who better to ask: ‘What does an observer actually do?’

Lt Stephens said: “I must have tried to explain to my mother a dozen times what I do in the navy, but never really succeed.

“The name is ‘observer’ and it comes from someone with binoculars watching from an aircraft in the First World War. We stick to it in the navy, but other nations use names like tactical mission commanders or aircraft warfare officers. I think the mission commander definition is probably the closest.

“The pilots are flying the aircraft, which the observer needs to know about of course, but as well as that you have all the information from the aircrewman with their sonics, all the information from the warfare officer on a ship, such as a frigate, and your own information from the radar. Fundamentally, the observer is in charge of all of that.

“Also, if you ever get to the point when you have to drop a weapon [a torpedo], the P-WO (principle warfare officer) makes that decision but we’re the ones who have to get the aircraft into the right position and press the button.

“On top of that, we’ve also got the safety of the aircraft to consider. We need to operate at low level, be in the right place and get back to the ship again."

So, it I part mission commander, radar operator, weapons officer and navigator and much more – far from just observing.