There is no general legal requirement in the UK for British civil aircraft to be fitted with an Airborne Integrated Data System. Although the Air Navigation Order requires all aircraft over 5700 kg maximum take-off weight with a Transport Category Certificate of Airworthiness to carry some form of crash recorder, this is not necessarily associated with an AIDS. However, in two areas AIDS have virtually been a requirement as part of the certification process. On Concorde the Anglo-French certification authorities produced a totally new set of airworthiness requirements to match the advanced and novel features of the aircraft. The several new and previously untried approaches to airworthiness, and the state-of-the-art of AIDS recording, caused the joint authorities specifically to require the analysis of in-service flight recorder data to validate certain certification assumptions. The Supersonic Transport Aircraft Requirements state ‘… it will be necessary … to gather, as far as possible, flight statistical data both before certification and in subsequent commercial operations. This information will be compared with the assumptions made for the application of the requirement (e.g. assumptions as regards system reliability, statistics of turbulence, etc).’

It is usual to consider AIDS as applicable mainly to digital data; this data can usefully be divided into two main data management requirements that are unlikely to integrate for many years.

Data is required for active control of the aircraft and weapons system. This data must be immediately available to the pilot, aircraft and weapons control system; its integrity tends to demand triplex or quadruplex data sources with comprehensive Built In Test and reversionary mode operation under fault conditions. Some data also needs to be stored to aid subsequent fault diagnosis and ground maintenance but usually represents a very low data storage and analysis requirement.

Despite the many learned books and articles which have treated the theory of spinning in some depth, there still remains an aura of black magic about it. This article is written in an attempt to explain the spin in simple language and hopefully to take away some of the black magic. It has been written primarily with the HS Gnat in mind, because, although it is forbidden to spin a Gnat, there have been incidents over the past fifteen years that it has been in service, where even experienced pilots have got into spin prone situations. Now, it might be said, that a new generation of pilots has emerged who do not appreciate the reasons for the prohibition of Gnat spinning, which have been lost in the mists of antiquity.