To clarify, you say a crew of five is carried - so is this a driver, an officer to co-ordinate (front passenger seat) and three regular firemen (seated in the back area of the cab)? You showed six men standing outside the truck, so I am slightly confused.
Presumably each man has a specific duty upon reaching the scene - could you run us through a typical callout to an actual fire, with pictures, naming or numbering the klickies so I can keep track?
Wel spotted, Martin, but I did say a crew of five is carried usually.
I must admit the text is from an earlier posting some years ago when I limited the crew to five because having a full crew of six in with the reflective jackets on made getting them in and out awkward, but six were carried at a push. However, since these pictures were taken, to overcome the problem of access only the grey uniformed klickies man this appliance and that does allow six to be carried.
In the British fire service there is only one specialist firefighter and that is the turntable ladder operator. Most TLs have just a normal two-man cab and usually attend an incident just crewed by a driver (although a new style appliance very similar to the 3781 is coming into use which is multi-functional and I'll post some pictures of one). Once at an incident, the driver of the TL does his job of turntable ladder operator and crew from other appliances actually go up the ladder and operate the pump if the TL is fitted with one.
In the case of the 3781, the driver is the TL operator and the rest of the crew take up whatever duties needed, being assigned them by the firefighter in charge, who may be an officer but could be a sub-officer or a leading firefighter (these are the fire service equivalent of NCOs). The advantage of the 3781 carrying a crew of six is that five crew can be available for firefighting duties when an officer isn't carried. The disposition then would be driver operating the TL, one firefighter operating the pump and also dealing with communications and acting as overall in charge and two teams of two firefighters each to carry out search and rescue duties and firefighting. If an officer is carried, then you only have three available for firefighting and rescue work, one of whom will act as pump operator leaving (if needed) and a team of two for firefighting/rescue.