Regardless of the debate above, you all need to remember this:
Statutory Instrument 1996 No. 2798
The Civil Aviation (Investigation of Air Accidents and Incidents) Regulations 1996
(4) Subject to paragraphs (5) and (6) below, the Chief Inspector may, when he expects to draw air safety lessons from it, carry out, or cause an Inspector to carry out, an investigation into an incident, other than a serious incident, which occurs—