Synthetic vision mandatory for this kind of operation.
Agree but with which money ? and as 172 driver says : who is going to make and pay for the database ?
Reality check : Nepal is a the bottom of the list of poor Countries in the world and the recent earthquake is not helping improving things.
Most domestic aircraft on the Nepalese register , e.g the Dorniers , the old Twins and the Beechs have a Garmin 296 taped on the dashboard for navigation . No ILS anywhere , not even in Kathmandu. Even the Buddha ATRs fly VFR inside Nepal, and Buddah is one of the good airlines.
Ironically this brand new Twin Otter had ( according my info) a Garmin glass cockpit and terrain/EGPWs on the display, probably one of the only ones around, so I do not think navigation was an issue.
The route to fly from PKR to JMO is well known, is it inside a deep valley with 7000 peaks on either side , where the a/c crashed you have the Tukuche a 6900m on the left and the Anapurna South at 7200m on the right. If you can see the ground and follow the river you get to Jomsom without any problems.
My wild guess is that then entered bad wx lost sight of the flat ground below and decided to turn around and something went wrong during the 180.
But speculating .
Now, those who have ever attempted a 180 in bad wx ahead in a deep valley getting smaller and rising in up can throw the first stones at the crew.
And for those who always have a technological answer Mr. Garmin is not going to help you perform that 180 either, on the contrary even..