Single engine passenger commercial operations are already permitted by rule changes in the USA (since 1988), Canada (1993), Australia (1997), South Africa, New Zealand and the great majority of advanced aviation nations. Cargo only operations are also permitted by exemption in Denmark, Finland, France, Greenland, Norway and Sweden. Switzerland has also stated that it will now approve both passenger and cargo operations in accordance with the NPA.

The European Joint Aviation Authorities produced an Advance Notice of Proposed Amendment in 1998 to allow commercial operations at night and/or in IMC by single- engined turboprops. The basic proposals were supported by 13 of the 14 European Authorities which gave their position, only the UK CAA being opposed.

The FAA (USA), Transport Canada and CASA (Australia) also responded to the consultation, all giving their support. A new JAA Working Group was formed and completed its work in December 2001 and the Notice of Proposed Amendment has been published on the JAA web-site with an invitation for comments as the start of the consultation process and will be sent out as 'hard copy' on July 1st.2002. This NPA is intended to allow passenger or cargo commercial operations at night and/or in IMC by single- engined aeroplanes with 'very reliable' engines (in practice today this limits the potential approvals to certain turboprop aeroplanes).

ICAO's Operations Panel Working Group 1 has been tasked with developing proposals to amend its Standards and Recommended Practices to allow passenger or cargo commercial operations at night and/or in IMC. The initial draft is based on the JAA NPA but the consensus view in this wider forum so far has resulted in a number of alleviations to the detailed technical requirements relative to the NPA, as some of the latter were considered to be unnecessary and unrealistic. It seems to be possible, therefore, that the JAA NPA may be amended after consultation to incorporate some of these alleviations to reflect the wider international viewpoint and to improve harmonisation with the FAA and other countries.

The JAA work has shown that modern single-engined turboprops have an overall fatal accident rate that is clearly better than the average for 'comparable' (in capability and price) light twins - piston and turboprop combined. To allow commercial operations at night and in IMC by such single turboprops will therefore result in an important increase in safety for the pilots and passengers.

The JAA work, to which the CAA contributed in a major way, resulted in the conclusion that modern single-engined turboprops in commercial operations in western countries since 1990 have had an overall Fatal Accident Rate of 5.0 per million hours, whilst 'comparable' light twins (piston and turboprop combined) have a rate of 8.5. These figures are quoted in the first paragraph of the Preamble to the JAA NPA (primarily drafted by CAA) and the CAA has indicated their acceptance of these figures.

Piston twins have a higher accident rate than turboprops and NTSB data shows that US commercial Part 135 operations by piston twins resulted in a Fatal Accident Rate of 12.1 per million hours (see paragraph 4.2 of the JAA Report of the Accident Analysis Sub-Group, SE-IMC/AASG/7 of 16 November 2001). Thus by using single engine turboprop aircraft the safety could improve by a factor of 2 to 3 (a potential Fatal Accident Rate of 5.0 rather than 12.1).

The probable benefit would, in fact, be higher as the NPA contains more stringent requirements in crew training, equipment fit and operational limitations than are applied in other western countries

for which the above accident figures apply.

Work in the JAA Working Groups has included analysis of the risks associated with engine failure in modern single turboprops whilst in the cruise (and also during Standard Instrument Departures and Approaches) taking account of the global engine failure risk in each phase of flight and the risks of a fatal accident in the subsequent forced landing. (The NPA requires an engine loss of power rate of less than one per 100,000 hours). The analysis for the cruise phase shows that the increase in the Fatal Accident Rate due to, say, a 30 minute cruise segment where no 'suitable landing area' is available is less than 0.5%, ie insignificant, whereas the enhanced requirements in the NPA relative to the rest of the world must be expected to result in a much more important improvement. Thus on the basis of the exceptional engine reliability required over-water flights should also be allowed.

Air Medical at Oxford and Centreline at Bristol have already purchased Cessna Super Cargomaster aircraft. Captain Rod Paris of Air Med says he chose the Caravan for its ability to carry one and a half tonnes over short distances and one tonne of cargo from the Midlands direct to Gibraltar. No other aircraft offers such versatility and economy of operation, he says.

We anticipate that now the NPA has been issued then other fleet operators will soon take advantage of the change in regulations by placing orders for both Grand Caravans and more Super Cargomasters.

The JAA has now published the SEIMC NPA, which can be viewed at www.jaa.nlunderPublicationsOPS-29.

Bob Crowe, www.bobcroweaircraft.com