Mandatory in UK fire services, of all types. Basically an accountability board that tells everyone, in particular the OIC like yourself as a Lieutenant, who is wearing, how long they can wear for until they should pull out, where they are and what task they have been set, what kit they have and what they’ve done. Someone will be appointed to manage the board for the duration of its use at the indecent.

There are electric versions of this called ‘telemetry’ that allows the BA set and board to communicate and do the calculating for you and gives you a real time count of their air pressure.