The top event describes the point where we no longer have
adequate control over the hazard.
It is usually what we consider to be an unsafe state that is not yet an accident. Therefore, top
events while not being disasters themselves have the potential to become disasters if nothing is
done to control them.
In our driving a car on a busy motorway example, the top event could be described as losing
control of the car.
A point in time which describes the release or loss of control over a Hazard. The undesired
The top event is described as a loss of control event (not relevant to the Significant Seven)
but in a context of an undesired safety state. By defining this, we are able to consider multiple
potential causes for the loss of control and the various potential outcomes (as opposed to
considering just one fixed accident chain).
If you find that you are not examining the area you are most interested in, consider if it would
be reasonable to redefine the top event either left or right to suit your needs.
Read all @UK_CAA
South Coast and South West drone users invited to ‘Share the air’ event at Compton Abbas airfield
17 October, 2017
ADS-B can help reduce airspace infringements and mid-air collisions, says CAA
16 August, 2017
CAA statement on Government drone consultation response
24 July, 2017
Read all News
‘Share the Air’ gets off to a flying start
1 December, 2017
Mandatory occurrence reporting
7 December, 2016
Guidance for flying drones
17 May, 2016
Read All Blogs