It is less than a week since a Russian passenger jet crashed in Egypt's Sinai peninsula and already details of its black box recordings are leaking out, shedding light on the stricken aircraft's final moments.

Routine conversations between crew members turned to panic. There were sounds "uncharacteristic of a standard flight" and a "sudden emergency situation on board".

US satellites reportedly picked up a momentary heat flash around the time of Airbus jet's disappearance, and we know that the plane broke up in mid-air.

Pilot error and technical malfunction have been ruled out, and a missile attack by Islamic State-linked militants is apparently "off the table".

Downing Street said last night it believes a Lockerbie-style "explosive device" may be to blame, but physical fault is also possible. Some experts have pointed to previous tail damage in 2001 which may ultimately have led the fuselage to break off during Saturday's ill-fated flight. The same situation doomed a Japan Airlines' Boeing 747 in 1985.

The bottom line is, it is unlikely to remain a mystery.

In comparison, Scotland's own worst on-land air crash of recent years - the Clutha helicopter disaster - has left a puzzle that even a Fatal Accident Inquiry may never resolve.

It is hard to imagine how unsatisfying that is for family members who lost loved ones, and for those left injured or traumatised by events that night.

There has been much speculation in the past two weeks since the Air Accidents Investigation Branch released its final report, and some of the more lurid theories are worth addressing.

Some commentators pointed to the example of the Germanwings crash and asked why journalists "weren't asking the right questions". What about the pilot's mental health, his private life? - implying he may have taken his own life.

The lack of reporting along these lines does not necessarily mean those questions have not been asked - more likely that there is nothing to be found.

If Captain Traill wanted to kill himself and others, there were far easier ways of going about it than turning off some fuel flow switches and waiting for the engines to cut out. Why even bother calling in to request permission to land if you have no intention of doing so?

There have also been the inevitable conspiracy theories - a corporate cover-up, for example. Again, it is worth noting the AAIB has not shied away from finding fault with manufacturers in the past, so why would they make an exception with Clutha?

A "catastrophic failure" in the main gearbox was blamed for the fatal ditching of a Super Puma helicopter in 2009, which claimed the lives of 16 offshore workers and crew.

The fact the Clutha helicopter had a history of malfunctioning fuel tank sensors may go some way to explaining the pilot's behaviour, but it seems they were working correctly on the night.

The cockpit switches which could be turned off with a "light finger touch", suspending fuel transfer, may also merit modification to eliminate the risk of them being knocked out accidentally - at least one possible explanation for what unfolded.

The FAI will put the tragedy under the microscope, but without a black box the truth may never emerge.