Which system is least complicated and used for emergency oxygen supply in pressurized aircraft?

The least complicated system used for emergency oxygen supply in pressurized aircraft is the chemical oxygen generator system. This system operates through a simple chemical reaction that produces oxygen when a chemical compound is ignited. It requires minimal maintenance and has a straightforward design, making it highly reliable for emergency situations.

Chemical oxygen generators are typically compact and lightweight, which is essential for aircraft applications where space and weight constraints are critical. When activated, these generators produce oxygen quickly and efficiently without the need for complex mechanisms or storage systems associated with other oxygen supply systems.

In contrast, other systems such as compressed gas systems involve gas storage under high pressure, requiring robust design and careful maintenance to prevent failures. Liquid oxygen systems need specialized storage conditions due to very low temperatures and handling procedures, while mixed gas systems may involve elaborate mixing processes that add to their complexity. Therefore, the chemical oxygen generator is favored for its simplicity and reliability in emergency scenarios.