When can cell phones be used on Frontier flights according to regulations?

The correct answer pertains to specific guidelines regarding the use of cell phones on Frontier flights, focused on safety and operational protocols. When traveling with an airline, including Frontier, passengers are generally permitted to use their cell phones until the doors close in preparation for departure, during ground delays, and provided they have obtained permission from the captain. This policy is rooted in maintaining safety within the aircraft and ensuring that all communications necessary for operations can proceed without interference.

During critical phases such as taxi and takeoff, regulations and airline policies prioritize crew communication and passenger safety, leading to restrictions on device usage. Hence, the correct context provided by this answer is that there are designated times when passengers can use their phones while ensuring that it does not disrupt vital cockpit communications.

The other options do not align with this established policy. The use of cell phones when at cruising altitude alone fails to encompass the full range of permissible scenarios. Moreover, using devices during taxi would not accommodate the regulations designed to prevent distractions during crucial operational phases. Finally, the notion of using phones at any time not affecting crew communication is too vague and does not reflect the specific operational protocol required by airlines.