Does the app work without an internet connection during a flight?

While cruising, cellular service is either unavailable or intermittent. A reliable app must be able to function in a degraded offline mode.

• Aeronautical charts must be downloadable in advance to the device.
• GPS navigation works without a network connection (the GPS receiver is standalone).
• Documents, checklists, and frequencies must remain accessible without a connection.

Be wary of apps that require a constant connection: they become unusable as soon as the engine starts.