A DRA is normally used when the environment or the risk may be uncertain. It is usually a simple checklist that the operator ticks off when arriving on site or assessing the job in hand. Typical work would be working on a roof. Checklist should include safe access, roof ladders, edge protection, skylights, fragile roof warnings, harness points and even the prevailing weather. Obviously the list is not exhaustive.

the points noted in a dynamic RA could be made permanent at an early stage e.g. added to the specific RA's for given area but remember there will always be a case for a dynamic 'RA' as situations change

Dynamic risk assessments are used by the police in developing incidents, however they are also used to support the risk assessment which may have been written whilst planning for an event. The dynamic risk assessment is carried out prior to starting work on the day having read the original risk assessment and seeing if circumstances have changed. Would I document it, possibly yes if there are significant differences and I would document it on the original assessment. Have I used the dynamic risk assessment process - yes - many time whilst working for the police as a safety officer, it was also a way of ensuring they were included in the risk assessment should a similar task be carried out in the future. It is good practice to stand back and review what is written.