Very Tragic.
It would appear, however, from an article in the Daily Record, that they were not carrying AVDs. For the uninitiated, these are small battery powered short-range radio transceivers that greatly facilitate the recovery of avalanche victims. In my ski-mountaineering club here in France, we are not allowed out on the mountains in winter without AVDs, collapsible 3m probe and folding shovel. We also practise regularly their use. Statistics show that 92% of victims survive if recovered within 15 minutes, thereafter the percentage drops off a cliff down to about 10%. The best chance of survival therefore comes from other members of the climbing party being equipped and trained to carry out the recovery. By the time a helicopter arrives, it is usually too late.
This equipment is not expensive at all, and I am surprised that the RAFMA would appear not to require members of the party to carry it in any conditions where there is a risk of avalanche.
There also appears to have been a lack of awareness of avalanche risk as the article mentions that "two parties were on opposite sides of the valley". In general the avalanche risk in a valley is greater on one side than another, depending on wind direction and orientation to the sun, so it would appear to be that one of the parties was taking an unnecessary risk. I don't know the valley where the accident took place, but given that the snow was "like concrete" this suggests that they may have been on a south facing slope which has been subjected to thaw-freeze cycles. Here in France the excellent Meteo-France website puts out detailed avalanche risk forecasts which take into account weather patterns for the past two weeks and which are indispensable in route-planning. I don't know whether the UKMO puts out similar information.
Here is the Daily Record article:
Rescuer tells how Cairngorms avalanche victims were buried in snow 'like liquid concrete' for hours - Daily Record