Paper Maps, Pre-flight planning and Rules of thumbs can catch simple mistakes
I went cross country with a student last week in the mighty Grob 103, we covered about 100 km. The student (actually he has a license) has been very reluctant to go cross country in his own glider. We looked at the weather and he had been watching SkySight for a few days. The forecast wasn’t very promising but we talked and figured out our Go/No Go points. He was also flying with his LXNav Nano 4, which he normally uses as his backup.
He figured out an important part, how to change waypoints. I have mentioned this before, be very familiar with your backup systems. We always kept glide back home and once we climbed (which took nearly an hour), we were at cloudbase at around 10,000 ft. This was way better than forecast and clouds were starting to form. We started looking at our next airport which we had glide to and were off following clouds with no worry about returning home because we were heading south and had our next airport within glide, even though we were not yet to our Go/No Go point we plotted on paper, it was clear we would make it. We did talk about the Go/No Go point as we passed over it. Looking over his shoulder I could see the altitude above glide on the Nano 4, the numbers seemed to be pretty optimistic for the mighty Grob 103.
A few climbs later and 20 min left in our lesson we started to make our return trip home. Again we were not near our Go/No Go, but I asked how we were doing. He claimed some great numbers (altitude above glide) from the Nano 4 and was pretty happy about heading home. Looking outside home looked a long way from us. It definitely did not look like I would want to be 250 0ft lower than we were.
Remember these magnificent electronics are garbage in, garbage out… The issue was our flight was originally planned for using our Stemme S10vt, however, it is down for a prop overhaul. His Nano 4 still was programmed for the S10vt. Which means the computer would have landed us out somewhere short of home. Once he programmed the Grob103, our reserve altitude went to nothing. On top of that, he felt just having a 1000 ft safety margin was fine, unfortunately with big thermals comes big sink, and having an MC=0 is an unattainable glide ratio. In previous articles, I talk about using a MC=6. My paper chart was using a 50% safety margin. Many people use 200 ft per mile but that is 26:1 and I like having a little more in the 103.
The other neat thing about the cross country was how simple we made the planning. We stayed within glide of our home airport until we could make the next one. Then we forgot about going home and just kept going. On our way home we were stuck at that other airport until we could make glide back home, then we would go. It can be very intimidating and there is a lot to the judgment, but if you can simplify the safety aspect of it is a lot easier. Worse case is your thermal reading isn’t that good and you safely land at the next airport. Plus our towpilots like doing aero retrieves.
Garret Willat holds a flight instructor rating with over 8000 hours in sailplanes. His parents have owned Sky Sailing Inc. since 1979. He started instructing the day after his 18th birthday. Since then, Garret has represented the US Junior team in 2003 and 2005. He graduated from Embry-Riddle with a bachelor's degree in Professional Aeronautics. Garret represented the US Open Class team in 2008 and 2010 and the Club Class team in 2014. Garret has won 3 US National Championships.