What Apple iOS versions does ForeFlight support?

Minimum iOS Version: 

The current minimum iOS version supported by ForeFlight is iOS 10.3. Additionally, some features in ForeFlight require iOS 11.

iOS 11 will become the minimum iOS version for new versions of ForeFlight in January 2019. Devices that are not running at least iOS 11 will not be able to update the app beyond version 10.6.