Which of the following is important to check before driving a vehicle airside?

Before driving a vehicle airside, it is crucial to check the vehicle's brakes, tires, and overall operational condition. This is important for ensuring safety while operating in a potentially high-risk environment such as an airport. The brakes must be fully functional to allow for safe stopping, while the tires need to be in good condition to provide proper traction, especially on various surfaces commonly found airside.

Additionally, the overall operational condition encompasses checks on the lights, fluid levels, and any other essential components necessary for the vehicle's safe operation. Any malfunction in these areas could lead to accidents or situations that may endanger not only the driver but also others working or moving in the airside area.

The other choices focus on aspects that, while relevant in certain contexts, do not encompass the critical safety checks necessary prior to operating a vehicle in an airside environment. Fuel level is important for ensuring the vehicle can operate but does not address immediate safety concerns linked to the vehicle's ability to stop or maneuver effectively. GPS functionality might assist with navigation but does not impact the foundational safety aspects. Lastly, driver comfort is certainly a part of the overall driving experience but is not a priority in assessing safety and operational readiness before entering an airside area.