Archives For HOT

Recent work in complexity and robustness theory for engineered systems has highlighted that the architecture with which these systems are designed inherently leads to ‘robust yet fragile’ behavior. This vulnerability has strong implications for the human operator when he or she is expected to intervene in response to the failure of system.

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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).

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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…

Pitot sensor (Source: BEA)

The theory of Highly Optimised Tolerance (HOT) predicts that as technological systems evolve to become more robust to common perturbations they still remain vulnerable to rare events (Carlson, Doyle 2002) and this theory may give us an insight into the performance of modern integrated air data systems in the face of in-flight icing incidents. 

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