Synthetic Vision requires you have an up-to-date version of the ForeFlight Mobile EFB. If needed, here is a link to step-by-step instructions on updating your app to the latest version: www.foreflight.com/support/app-update
To start using Synthetic Vision on your iPad, please do the following:
1. Open ForeFlight Mobile and tap on MORE > DOWNLOADS > UNITED STATES and turn the HIGH RESOLUTION TERRAIN switch to ON. (Or in place of the United States, select the area you require).
2. Tap the black "Downloads" BACK BUTTON to go back.
3. Tap the blue DOWNLOAD button to download the High-Resolution Terrain data.
4. Go to the MAPS page.
5. Tap the SYNTHETIC VISION button at the top of page (looks like a banked-over Attitude Indicator) to display the Synthetic Vision view.
NOTE: If you don't have a source for pitch and roll information, an external AHRS (Attitude Heading Reference System) unit is needed. This can be provided by a Sentry http://flywithsentry.com/
Without an AHRS unit, you will see the Terrain and Obstacles but no attitude (pitch/roll) information.