The turret was surrounded by a fairing which contained a cam track. By restricting the movement of the guns, this ensured that he couldn't damage his own aircraft when firing. When the guns were elevated at 20 degrees or more, turret traverse was fast and smooth, but below this it was much slower.
This was to avoid damage to the turret firing at full depression, but in action, it was a serious disadvantage as it made tracking a fast moving enemy fighter very difficult.
In an emergency the Mid-Upper Gunner had to squirm out of the turret, retrieve his parachute from its stowage and depart through the door by which he entered. Just ahead of the mid-upper turret was an escape hatch in the fuselage rood, which was to be used in the event of a crash landing or a ditching at sea.