Hi

When planning a flight fro Denmark to Marocco in a Cirrus SR22T with indicated speed 170kt I get data for Best altitude. If I change to a Cessna 172 with indicated speed of 100kt I get no data. What is the correlation between speed and Best altitude?

Thanks Tim, that make sense, but for someone that do not know the relation between performance data and Best altitude it will be a puzzle. Any chance to create a hint why it say Incomplete Forecast?

Now I can make better planning - great!