Nearly 700 days have passed since a police helicopter fell out of the night sky onto a busy pub on a Friday evening on Glasgow's Clydeside.

The 160-page report yesterday published by the Air Accidents Investigation Branch has answered many questions. But there are other questions that remain unanswered, even now. The grieving families of the 10 people who died are still in the dark. It is impossible not to feel for them.

Why, they want to know, did David Traill, the helicopter pilot, continue to fly for 22 minutes despite receiving continuous low-fuel alerts that were flashing for both of the helicopter's engines? Why did he ignore strict rules by not landing the helicopter within the mandated 10 minutes? Why were two fuel-supply switches in the cockpit incorrectly turned off - an action that led to the engines cutting out? There was, as the AAIB report makes clear, "no explanation" for both being switched off.

It has to be borne in mind that the AAIB is an independent body, whose task is to look into the causes of accidents in order to prevent any recurrence and to help make aviation safer. It does not seek to apportion any blame, nor should it. Its safety recommendations deserve to be heeded.

But it is difficult not to look at the events of November 29, 2013, from the families' point of view. Each anniversary of the tragedy will be very hard for them. Next month's will be observed particularly acutely due to the report's publication.

If they had hoped against hope that the report would explain why the tragedy happened - which, after all, is the most pressing question in such harrowing circumstances - they will be feeling anger and frustration today. As the First Minister has said, it is "deeply disappointing" that the report has not reached a clearer conclusion. In some respects, Nicola Sturgeon added, it has seemed to raise more questions than it answers.

The Crown Office is to hold a Fatal Accident Inquiry, though it is unclear at this stage if the reasons behind the tragedy will emerge, even then.

In such a context, then, one AAIB recommendation - that European and British civil aviation regulators require all police and medical helicopters to carry flight recording equipment - makes sense. This is something the relatives have been seeking for some time. Airbus is set to install in-cockpit cameras on its helicopters in addition to black boxes.

Flight recorders (either black box or voice cockpit recorders) would not have prevented the Clutha crash but they would have at least shed some light on what was happening in the cockpit in those last few minutes.

Did Mr Traill believe the fuel sensors in the tanks were malfunctioning and therefore that the low-fuel warnings he was getting were erroneous? Was it all a genuine error of judgement?

Black boxes might perhaps have explained these, and other, questions. As things stand, we - and the families - may never know the answers