BOAC #4528
What do we really think of the HoL enquiry? - quote Lord Burnham (9:40 PM)
"The pilots were navigating by the relatively primitive TANS—tactical air navigation system—which did not at that time have a GPS input." Really does not a lot of credit to his 'learned' comments if it is rubbish.
I think this slight confusion over GPS and SuperTANS (RNS252) may be explained by the limitations in the CA Release (and hence Release to Service, as the latter simply subsumes the former);
Section O – Navigation Installations
2.2 TNL 8000 GPS – GPS has not yet been declared operational (at IOC) by the US Department of Defense and accuracy is therefore not guaranteed to any level.
2.3 (a) RNS252 GPS (Ext) Position – In addition to paragraph 2.2 above, the GPS is highly susceptible to jamming of which the only crew indication is loss of GPS. ….. The “Err” figure displayed, which has conventionally been taken as a measure of GPS performance, is meaningless and so no indication of the accuracy of the GPS is available to the user.
Now, in the context of various statements that the aircraft was “serviceable”, I ask – How do you know, and how were the pilots to know? How was it demonstrated? And, is there any wonder why the pilots didn’t trust the system?
I also ask a very simple question, which the regulations mandate as part of the process of considering the aircraft for (a) CA Release and (b) Release to Service – Given the above, and considering the fact that the FADEC software was still in the development phase at the time of the crash (as it hadn’t been validated or verified to the laid down standards), do you think this was a mature design and fit for purpose?
It matters not a jot that with hindsight the “system” turned out to be reasonably accurate – evidence shows that this was something of a hit and miss affair with other aircraft experiencing errors of up to 2nm over a similar route. What is vitally important here is the lack of confidence the crew had in the system - the human factors element of airworthiness. This has simply not been addressed by the BoI or ROs. This lack of confidence led one pilot to ask for a Mk1. Rather conveniently, this line if investigation was not pursued.
The above are direct quotes from the Master Airworthiness Reference. No wonder the ROs didn’t want the BoI to go anywhere near Airworthiness. Gross Negligence? I know who committed it and it wasn’t the pilots.