What type of oxygen generation is used on all aircraft except B747 and B787?

The use of chemically generated oxygen on most aircraft, with the exception of the B747 and B787, is based on the requirements for emergency situations where supplemental oxygen is essential for passenger and crew safety. Chemically generated oxygen systems use chemical reactions to produce oxygen instantly, which is crucial in emergencies where passengers may need to utilize oxygen masks quickly in case of cabin depressurization.

This method is advantageous because it has a lower weight and can be stored compactly, making it ideal for aircraft design and safety protocols. The chemical oxygen generators provide a reliable and efficient source of oxygen that can be activated by the user in an emergency situation.

In contrast, other methods like compressed oxygen require heavy tanks and involve additional considerations for maintenance and pressure checks, while electrical oxygen generation is less common in commercial aviation due to limitations in current technology for immediate oxygen availability. Liquid oxygen systems, while efficient, are not widely used in commercial jets due to safety concerns associated with cryogenic storage. Thus, chemically generated oxygen is the preferred choice for the majority of aircraft in emergency scenarios.