Not density related, but one of my more interesting flights in PNG was as a passenger (in the RH seat) of a C402 into a small strip at Nuku in the West Sepik. Approach to the strip is over a ridge on the opposite side of the valley, below treetop height, through a gap in the middle of a village, with moderate power and full flap, then immediately clear of the ridge, maximum angle of sideslip to lose altitude down to the threshold, straighten up for touchdown, then full throttle - to keep it moving up to the top of the strip (let it stop and you will need the station tractor to get to the top). At the top of the strip, turn across the slope so you are not relying on brakes to avoid finding the plane at the bottom of the valley in an unairworthy condition. And turn off fuel tank crossfeed.
Takeoff (in the C402 is with very limited payload) is in the opposite direction, and turn down the valley once airborne.
Much less drama in a BN2a that has an approach speed of about 45kts compared to the C402 of about 100kts. And can depart at MTOW.
