One particular area of interest was the airworthiness of aeroplanes — Page 57, Lesson 104

I want to walk you through the start of Chapter 3, "Airworthiness of Aircraft." This is where we begin to understand how an aircraft is legally certified as safe to fly, and it's a foundational concept for everything you'll do as a professional pilot. Let's start with the background. The Chicago Convention, which is the international treaty that governs civil aviation, placed great emphasis on safety. One particular area of interest was the airworthiness of aeroplanes. To ensure an aeroplane was safe to use, it was agreed that every aeroplane would have a certificate stating that the aircraft was airworthy when it was manufactured. And crucially, through the continued validation of that certificate, the continuing airworthiness of the aircraft would be ensured. So you have two distinct ideas here: the initial certificate at manufacture, and the ongoing validation that keeps it airworthy throughout its life. Now, during the design and building stage of the life of a type of aeroplane, rigorous rules and regulations are applied to the manufacturing processes and the flight testing process. The goal is to ensure that the aircraft does what it is intended to do. Once the testing procedures have been successfully completed, the State of Manufacture issues a Type Certificate. Let me define that clearly: the State of Manufacture is the country where the aircraft is built — the USA in the case of Boeing aircraft, and France in the case of Airbus. The Type Certificate is the document that approves the design of the type, and it's applicable to all subsequent production models. However, the certificate for each individual aircraft is issued by the State of Registry, and that happens after a short 'compliance' air test. So the State of Manufacture certifies the type, and the State of Registry certifies each individual aircraft against that type. The initial certificate would also be applicable to all subsequent marks or upgrades of the type, within reason. But here's the catch: the FAA and the UK CAA decided that the 747-400 was not the same aeroplane as the original 747, and they required re-certification. That was an expensive process for Boeing. So the lesson is that a major change to a type can trigger a fresh certification. For the initial flight testing, the prototype is permitted to fly under a Permit to Fly, which is issued by the State of Manufacture. So before the type is fully certified, the prototype flies under this special permit. Now let's move to standards. The airworthiness standards of Annex 8 of the Chicago Convention are related to the standards of Annex 6, Part 1, which deals with aeroplane performance operating limitations. An element of the safety of an operation is the intrinsic safety of the aircraft. That's the inherent safety built into the machine itself, as opposed to the safety provided by the crew or the procedures. Let me show you what a Certificate of Airworthiness looks like, so you can see the document we're talking about. That's the certificate that validates the airworthiness of an individual aircraft. So to tie it together: the Type Certificate approves the design, the Permit to Fly allows the prototype to test, and the Certificate of Airworthiness is what each production aircraft gets from its State of Registry.