Today's fatal crash of a Dornier 228-200 in Nepal was the second in the mountainous country this year and adds to a dreadful safety record of nine fatal crashes of twin turboprop commuter airliners in the last ten years, and many more before that.
The crashes in the last decade included three recent fatal accidents involving Dornier 228-series aircraft, four de Havilland Canada Twin Otters and one Beechcraft 1900D.
Twin-turboprops are the backbone of the country's domestic air transport sector and are used to ferry thousands of mountaineers and trekkers that visit Nepal each year to the remote airstrips in the Himalayas from which they can start their adventures.
As a flying environment Nepal is demanding. Kathmandu is in a deep valley where the visibility is frequently reduced by air pollution. Nepal's mountains, the highest in the world, are a terrain threat to aviation unlike any other. The fickleness of the local weather in the high valleys and in the vicinity of remote airfields is yet another considerable challenge to pilots.
Finally the airstrips themselves are notoriously challenging, with short runways that are uneven, sloping, or both, and with approach and departure paths obstructed by high ground. When the weather changes rapidly, pilots are faced with difficult decisions about whether it is safe to continue an approach, and if the weather closes in too fast, abandoning the approach may be equally risky.