Comment by aseg
9 hours ago
Gordo and Bruce are pioneers in the gliding world. One of their coolest flights that shows their creative flight planning shows up in their 3000km flight in the Sierra Nevada's, and the build up to it.
Some basics: The major challenge in flying gliders is the inherent stochasticity in the weather system. Think of it as a contextual bandit problem with high variance w.r.t local weather (i.e. Even the best planning cannot help if the weather doesn't comply). We have some observability due to forecasting tools (skysight.io) and any policy must have affordances for pilot skill and a margin of safety. A good pilot (or 'policy') starts with multiple plans, quickly modifies to plans to suit the environment, and can seamlessly switch between plans. The primary "reward signals" are duration of flight, distance covered, and (in competitions) hitting certain waypoints.
Previous WR's for longest flight were mostly in the Andes or Alps. You want to be in a mountain range to utilize either the [ridge lift](https://en.wikipedia.org/wiki/Orographic_lift) of a mountain face or [mountain wave](https://en.wikipedia.org/wiki/Lee_wave), ideally in a polar region during the summer to maximize the daylight hours so you can fly under VFR for longer.
However, while the Sierra Nevada's have great mountain wave and ridge lift, the number of daylight hours is not ``competitive''. Their main innovation was in acclimatizing themselves with using night vision goggles for long duration in a glider. There's an article on this [here](https://magazine.weglide.org/gliding-at-night-breaking-the-3...) which describes the acclimatizing flights and the 3k km flight in great detail. It doesn't get official recognition because the FAI requires the flight to be done in daylight, but still an extremely cool flight!
Can you speak more on why glider pilots need night vision googles to fly at night but single-engine pilots don’t? Is it the risk of landing out? Or are they flying closer to the terrain?
Not the OP, but I'd say both are yes. You will be flying in close proximity to mountains, no way you can do this without actually seeing the mountain.
My understanding is that (1) there is, as you say, a very nonzero risk of landing in a field and good visibility of what is _in_ that field is critical; (2) when riding thermals it is traditionally the case that many gliders soar in close proximity close to the core rising air mass, circling at quite a high bank angle – and collisions need to be avoided (many glider pilots wear parachutes for that reason…) and having visual references, particularly to mountains, really helps; and finally (3) it is common to be flying visually as one typically staircases in an altitude profile, as seen here, and go in and out of controlled airsapce (or deliberately avoid bumping into it, as I have done at 10 kft in UK airspace a long time ago).
In contrast, general aviation aircraft:
a) Have bright lights b) Will fly in a straight line at a well defined altitude, meaning that vertical separation is sufficient to deconflict aircraft c) Do not typically land in fields and do instead land on runways which often _also_ have bright lights.