In our brigade, we use coloured cow tags on a keyring.
Each firefighter has one or more tags with their name and crew number depending on their qualifications:
Yellow = firefighter
Red = CABA
Green = HAZMAT
Blue = RCR.
Obviously if you're a BA operator, you only have a red tag, not a yellow and red.
But if you're BA, HAZ and RCR you have
Red + Green + Blue. But at the moment we don't have any green tags because we haven't been able to get hold of any.
At the front of each appliance we have a board with hooks on it. One labelled driver, one OIC and then how ever many seats are left over depending on the appliance.
24P = 7
34 = 6
14 = 3
Before you jump on the truck you clip your tag on the board, which makes it easy for the OIC to see how many of what trained personell they have on board.
It also lets the control room staff know who is on the repsonding appliance.
Generally, depeding on the call, trained personell have first preference. For example if responded to a house fire, BA operators have first preference on 24P - the first responding appliance. However, we will not hold up the truck waiting for anymore than 4 operators on the first appliance, so we fill it up with non BA. BA operators who rock up just after will follow with the remaining crew on the second truck.
Basically, we try to get as many trained personell specific to the call on the first aplliance and what ever room is left over is filled with non-trained personell.
In doing this it also encourages people to undertake specialist training - which we all need more of - so that they get preferences on appliances. Very rarely do we leave many people behind, we try to get everybody who rocks up out to the job and try to be fair to everyone.
We can usually have the first truck out the door in 4 - 8 minutes depending on the time of day and available crew etc.
The second appliance usually follows 1 - 2 minutes later, depending on numbers and type of call as above.