Shawn,
The SARPs and advisory material for single-engine flight in IMC are included in ICAO Annex 6 Part III Revision 12. The SARPs are not just restricted to engine reliability, they include other elements to ensure that the Risk Profile remains acceptable.
Really enjoyed reading Rich's two posts, the second included almost the whole of the meaning of life in a capitalist society and then ended with ethical issues and global warming - phew!
However, it is easy to support the thrust of his argument - which was about risk management - because it is exactly that which drives the shape of regulations. Probably the only point missed was the level of safety demanded by society (the culture) - which establishes the targets for States/Regions. I would question Rich's contention "Thousands of people every day select low fare options over higher fares even when they are completely aware of the additional risks"; firstly with the low cost Air Transport Operators in Europe, there do not appear to be any additional (safety) risks - although there are some anti-social practices; and secondly, the average passenger in helicopters generally has no idea of the elements of risk that are extant for any flight (Norwegian offshore passengers excluded, they appear to be well aware of the risks and their power to minimise them).
The argument on comparative safety (NTSB over the amazon) is accepted as it is an integral part of the JAA culture.
As I understand it, the basis for the JAA philosophy is that flights over a hostile environment should be conducted by a helicopter certificated in Category A. The main reason for that is not performance - although it is an important element - but certification. As Nick Lappos has often stated, the certification basis for a Transport Category helicopter includes provisions that are not present for the Normal Category - except where that Normal Category helicopter is certificated to Appendix C of Part 27.
From the previous discussion it can be seen that: design assessment, fault tolerance, redundancy, compliance with 29.1309 etc., provide a level of confidence that the helicopter will continue to fly (usually related to some quantitative value). When this is characterised in a discussion about one or two engines it translates to a failure rate of 1:100,000 as opposed to one close to 1:1,000,000,000. Using the simplest analogy - because we all understand it - if an oil patch requires 400,000 hours to service all clients, there would be 4 engine failures/year. If those helicopters were singles, the result would be ditching but the consequence would depend on the water over which the flights are conducted. Clearly the GOM is (on most occasions) non-hostile but the North Sea (on most occasions) is hostile - hence there is no JAA prohibition on flying to helideck in a non-hostile environment because the consequence of a failure would likely be a safe-forced-landing.
As was stated earlier, there is no twin-only mentality but risk assessed regulations that take into account the hostile, non-hostile categorisation - i.e. it is not the failure that is important only the consequence.
The argument that simplicity is safer than complexity is a given, only the consequence of failure is in question.
Jim
Last edited by JimL; 12th Sep 2007 at 14:01.
Reason: Correction of the failure rate.