Thaw and Sierra Kilo 138…
11th February 2023
The wet and windy theme continued today, as the slow thaw continues to take hold. Reports from SAIS Forecasters out in the Creag Meagaidh area yesterday indicated that there was some variation in precipitation (I actually mean rain), between the Coire Ardair area and the eastern end of the massif approached from the Upper Spey.
This might mean the thawing snowpack has different characteristics from east to west. Visiting Coire Ardair today, the heavier rain of yesterday has clearly percolated through the snowpack resulting in a period of instability, evidenced by cornice debris in multiple locations from above Bellevue Buttress, under the post face and Inner Coire. In time this will bring consolidation of the snowpack, but at the moment wet snow instabilities still exist in steeper locations above 850 metres. These are mainly confined to the lee aspects of recent days, that is to say North, North-East, East and South-East aspects. The big picture is that of a Low Avalanche Hazard.
However, the threat of cornice collapse remains. There will almost certainly be cornices that linger above the big faces of Coire Ardair, although unfortunately the coire rim remained largely shrouded in cloud today.
Little change is expected tomorrow as the thaw continues. The freezing level is around 2800 metres, but it is likely the surface of the snow will be firm given a slightly more stable airmass than of late, combined with some radiation cooling. So while the snowpack will be saturated and soft in the vast majority of locations, don’t throw winter equipment out of the bag just yet! You might need the security of crampons and an axe at higher elevations tomorrow.
I have often wandered away from the path on the decent from Coire Ardair in search of the spot where Sea King ‘Sierra Kilo 138’ crashed on the 28 January 1989. Making an approach to the mountain rescue kit box close to the Lochan, the aircraft suffered a failure in one of two engines. It must have gone down on the only easy angled boggy ground in the otherwise steep corrie, preventing any significant injury of those on board (of which there were 9). The mountain rescue kit box is no longer there incidentally, and I have always assumed it used to be where the bench is now. I can’t remember from my early trips into the corrie, but perhaps somebody knows?
Anyway, today during my wanderings I found a small solitary shard of fuselage lying in the bog from XZ585 aka SK138. The location was NN440885 for those interested. Details at: https://aviation-safety.net/wikibase/137133
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