What are the primary functions of an aircraft’s electrical system?

The primary functions of an aircraft's electrical system center around providing electrical power essential for various operational systems on the aircraft. This includes powering navigation systems, communication equipment, lighting (both external and internal), and some engine functions. Each of these components plays a critical role in ensuring that the aircraft operates safely and efficiently.

Navigation systems require electrical power to function accurately, enabling pilots to determine their position and course during flight. Communication systems rely on electrical power to maintain contact with air traffic control and other aircraft, which is vital for maintaining situational awareness and safety in the airspace. Lighting is necessary both for visibility during takeoff, landing, and taxiing as well as for cockpit instrumentation. Additionally, certain engine functions, such as ignition and monitoring, depend on the electrical system to ensure proper engine performance.

Other choices, while related to aircraft operation, do not encompass the full spectrum of functions provided by the electrical system. The control of altitude and speed is primarily managed by the aircraft's flight control and propulsion systems, while hydraulic pressure is supplied by the hydraulic system, and cabin air pressure maintenance falls under the environmental control system's responsibilities. Thus, the electrical system is indeed fundamental for the specific functions listed in the correct choice.