If you are having a hard time seeing your iPad screen in the sunlight, the first thing to do is make sure your brightness is set to display brightly. To do this, open the iPad's SETTINGS APP and go to DISPLAY & BRIGHTNESS. Adjust the BRIGHTNESS SLIDER to FULL BRIGHT (Right Side).
Image 1. Open the iPad's SETTINGS APP and go to DISPLAY &BRIGHTNESS. Adjust the BRIGHTNESS SLIDER to FULL BRIGHT.
Next, open ForeFlight and go to MORE > SETTINGS and ensure the brightness slider at the top is set to FULL BRIGHT (to the right).
Image 2. Go to MORE > SETTINGS and slide the brightness slider to FULL BRIGHT.
To further reduce glare, a company called MyGoFlight makes a tempered glass screen overlay called ArmorGlass that is supposed to work well. You can learn more here: