Archives For Highly Optimised Tolerance

QF 72 (Image Source: Terence Ong)

The QF 72 accident illustrates the significant effects that ‘small field’ decisions can have on overall system safety Continue Reading…

The fallout from the QF 72 in flight accident has now reached the courts with Australian Aviation reporting that passengers and crew have taken up a joint class action against Airbus and Northrop Grumman (the manufacturer of the faulty Air Data Inertial Reference Unit).

Continue Reading...

Over the last couple of months I’ve posted on various incidents involving the Airbus A330 aircraft from the perspective of system safety. As these posts are scattered through my blog I thought I’d pull them together, the earliest post is at the bottom.

Continue Reading...

A330 Right hand AoA probes (Image source: ATSB)

I’ve just finished reading the ATSB’s second interim report on the the QF 72 in flight upset that resulted in two uncommaned pitch over events (1). In this accident one of the Air Data Inertial Reference Units (ADIRU) provided erroneous data in the form of transient spikes vales of the angle of attack AoA parameter to the flight control computers which then initiated two un-commanded extreme pitch overs.

This post is part of the Airbus aircraft family and system safety thread. Continue Reading…

If the theory of Highly Optimised Tolerance (HOT) theory holds true then we should be able to see a change in the distribution of the severity of adverse events as the design paradigm for a family of systems moves from the, ‘just make it work’ stage to the ‘optimise for robustness’ stage. This is something we can actually test through observation of real world systems.

Continue Reading...