This week's tip is from our archive. In How to fly the flatlands in Cross Country issue 133 we asked expert pilots for their advice.

Do you use the ‘thirds rule’ – divide the sky up into thirds and make your decisions based on the terrain when in the bottom third, on clouds in the top third and both in the middle section?

Steve Ham: On a day with cumulus I spend most of my time looking ahead at possible routes that the clouds will permit. Not just the obvious next cloud, but how the pattern continues beyond. Some of the streets are better formed than others, so it makes sense to set yourself up to run the best street well ahead of time. Thinking of how easy it is going to be 40km down the line when you hit that cloud street is a positive thing to think about on a glide rather than stressing about not connecting with the next Cu on route.

Dustin Martin: If it's a cloud day, I'll defer to a cloud all the way to the dirt. If I'm low and can’t reach any clouds then I’ll go for more productive terrain. But even then, I'll be much more interested in real-time signs of lift like dusties and birds.

Karel Vejchodsky: It’s a good rule. I use it automatically, not strictly into thirds but according to the current conditions. With a high cloudbase the rule is useful, if it’s low though I watch the sky and ground constantly.

Photo: Ed Ewing