For Silver badge and other flights with glider without PDA, there is old timer trick in order to start the flight.

You can consult a tutorial on official forums: http://condorsoaring.com/forums/viewtopic.php?t=4487

In short:

• Race’s clock must be started (you’ve heard the 3 bips)
• You have to be in the start sector (study the flight plan before entering the game!)
• Press J to see the start TP
• Look at 90° on your left, turn your glider to have both the TP basement and your left wing on the screen
• Press S key

If all points above are correct, you’ll see the confirmation message "xxx has started task". If you have only "Screenshot xxx saved", you have to retry.

Here is a video made by Bades to illustrate a flight without PDA.