First-hand look: Flying over Nepal’s flood disaster zone

The scars of disaster stretching from one valley to the next . There's no road to reach the high altitude villages decimated by last Wednesday's catastrophic flood . Right now, only helicopters can do the job . We're heading north now [music] up the Trishuli River . This is a really busy air corridor still more than a week after the devastating floods . And for most of these remote communities, helicopter is the only way to reach them given that all of the infrastructure has been destroyed . And from up here, the scale of the damage is shocking . An entire valley that's been wiped away . This is a hydropower corridor, but it's been ripped apart . From above, we spot the technical rescues underway at tunnel projects concentrated right along the Trishuli . Hundreds of workers may still be alive underground . They're running out of time . With each bend of the river comes the next town in pieces and the next . Above Timure, close to the border with China , very little to suggest a village once stood here . Bodies are still being pulled out of the mud . It's not safe to land. . A little further south, we set sights on Syabrubesi . Before last week, a popular stop for trekkers and pilgrims . We've landed in Syabrubesi . You can see a lot of helicopters coming in and out . There are rescue teams from Nepal and also from India . This is about 15 km from the border with China and further down closer to the river , the entire village has been wiped out . This riverside used to have hundreds of houses and hotels . 80% of them are now gone . We go down as far as the road still goes . This Buddhist shrine marks the end . It has partly survived . Inside, mud-spattered religious texts and statues