Well behind many other regions, and more than 10 years after initial proposals, Europe is about to rule on proposed commercial single-turbine-engine flights at night or in instrument meteorological conditions (SEIMC operations, roughly equivalent to flights under U.S. commercial single-engine instrument flight rules.) Approval is not certain, since some countries remain unconvinced about the safety of SEIMC services–even though some states permit cargo-only operations under exemptions or passenger operations within national airspace.

The Joint Aviation Authorities Committee (JAAC) will consider a proposed amendment to basic JAA fixed-wing operations requirements (JAR-OPS 1), but senior industry and regulation officials do not expect unanimous agreement among all constituent states. (The JAA promulgates regional aviation standards, but national authorities may apply local rules under exemption.)

If unresolved at the meeting scheduled for late this month in Cologne (Germany), responsibility for a ruling on the proposal–JAR OPS Notice of Proposed Amendment Number 29 (NPA 29), now in its 13th draft–could be handed on to the new European Aviation Safety Agency (EASA) when it begins to inherit aviation rulemaking from the JAA in October.

Advocates had hoped commercial SEIMC operations would get the green light more than three years ago, but discussion among national agencies and four rounds of industry consultation have only now produced a formal proposal from the JAA SEIMC working group.

A Long Road

For proponents, getting to this stage has been a frustrating saga.

The story so far: when the International Civil Aviation Organization (ICAO) was establishing standards in the late 1940s, almost all single-engine public-transport aircraft were restricted to daylight flights in visual meteorological conditions (VMC) and always within gliding distance of a suitable forced-landing site. The requirements were driven by relatively poor engine reliability, and ICAO member states were expected to incorporate these global standards in national regulations.

The advent of turbine engines in particular, with their absence of reciprocating parts, brought about huge increases in performance and reliability, but it took decades for rule makers to catch up. Indeed, it was not until 1988 that the FAA permitted such flights, and then only for freight, says the Single Engine Turbine Alliance (SETA), an industry lobby group pressing for SEIMC approval.

Slowly, other countries followed suit, and by 1997 Australia, Canada, New Zealand and South Africa permitted both passenger and cargo commercial SEIMC flights. Then, in 1998, the FAA approved passenger services, and joined Australian and Canadian regulators in producing a safety-benefit analysis and reporting satisfactory commercial SEIMC performance in service.

Also in 1998 the JAA opened the door to possible change when it published an Advanced Notice of Proposed Amendment to modify JAR-OPS 1 and established the SEIMC working group to gather industry input and draft what has become NPA 29.

Meanwhile, more than 20 ICAO countries have approved commercial SEIMC passenger/freight services, with three more member states permitting cargo-only operations. “Now, countries responsible for more than half of the world’s civil aviation approve SEIMC,” said SETA European representative Ron Ashford, a former JAA secretary-general and previously head of UK aviation safety regulation. “The three main single-engine turboprops (Cessna 208 [Caravan I], Pilatus PC-12, and [EADS] Socata TBM 700) have together flown about 10 million hours, about half on commercial flights, [and] more than 2,000 modern single-engine turboprops have been delivered to 70 countries.”

When–or rather, if–adopted, new regulations covering SEIMC services could be implemented immediately. Current European regulations prohibit public-transport SEIMC, except under special visual-flight clearance. Piper, Cessna, Pilatus and Socata set up SETA to lobby for regulatory reform to permit commercial operations. The alliance engaged Ashford and former U.S. FAA Administrator Langhorne Bond as consultants to argue the case that such single-engine turboprops are at least as safe as multi-engine machines.

Expanding SEIMC Ops

SEIMC operations have recently been approved in flight-information regions around Denmark and Greenland. Finland and Norway permit both passenger and freight services, while France, Spain and Sweden now approve cargo-only flights. In addition, Switzerland allows passenger and cargo services by Swiss companies flying Swiss-registered aircraft in Swiss airspace.

These initiatives have been offset in other European countries by national airworthiness regulators that have taken a more conservative approach to such operations, often voicing concern about carriage of fare-paying passengers in single-engine aircraft over populous districts at night or in cloud. Germany, the Netherlands, Italy and the UK have had the greatest reservations about the safety of such flights.

A major consideration for some has been the exposure that national regulators might feel to public criticism–and perhaps the possibility of litigation–if an aircraft came down fatally in a residential area as a result of failure of its sole engine, given a possible perception that two engines must be safer than one. For example, the UK Civil Aviation Authority has always been concerned about such operations, believing that forced landings at night “invariably lead to catastrophe,” Ashford told AIN.

Continued resistance by individual authorities could prevent JAAC unanimity–or even a consensus–say officials. “It is very difficult to judge,” said JAA operations director George Rebender. “One group is willing to make [the NPA] progress, but some are concerned.”

An example of an incident that could worry regulators was the street landing of a PC-12 in Indiana last December. Pilatus subsequently reported that initial findings showed that failure of the Pratt & Whitney Canada (P&WC) PT6 was caused by a pneumatic leak in the fuel control unit (FCU).

SEIMC working group chairman Tony Wassell is uncertain if JAAC unanimity is required: “I can’t give a definitive answer, as they normally operate by consensus. I believe [committee members] could approve on a majority, but I am not aware of any precedents. That is what makes the prediction of the outcome so difficult.”

Ashford believes unanimity is not required, but that compromise could be reached. Rebender said accommodation of dissenting national authorities through consensus is “a question for the JAAC chairman.”

Proposed Requirements

The latest NPA 29 proposal specifies a maximum time for any SEIMC flight to be out of still-air gliding range of a landing site during an accumulation of so-called ‘risk periods.’ Wassell told AIN, “One or more risk periods are permitted, provided these do not exceed a maximum of 15 minutes per flight.” Previous proposals (with allowance for restricted flight over water or inhospitable terrain) required flights always to be within reach of a landing site should power be lost.

The SEIMC working group has also written in requirements for systems and equipment enhancements and more comprehensive experience and training of pilots. Proposed engine-reliability requirements specify that power loss (such that a forced landing becomes inevitable) should occur at a rate of less than one per 100,000 hours of flight.

Recent work by SETA has provided better understanding of actual single-engine turboprop reliability in service since 1991. Considering available data for Caravan I, TBM 700 and PC-12 operations (up to Dec. 31, 2004, March 31, 2005, and Dec. 31, 2002, respectively), the lobby group says there have been 21 fatal accidents (all Caravan Is) in the period. These events occurred during a total of 4.928 million hours of “commercial operations [with these types] in western nations [having] safety standards equivalent to those to be expected in JAA countries.”

SETA said this is equivalent to 4.26 per million hours. Comparable overall turboprop fatal-accident rates ranged between 2.4 per million hours (worldwide Twin Otter scheduled operations) and 19.3 per million hours (UK turboprop airline operations). SEIMC working group members consider that this meets JAA requirements for single-engine turboprop performance to be as good as that of comparable light twins, said Ashford.

To accommodate the adoption of NPA 29, the current JAR OPS 1 rules have required modification to allow single-engine all-weather operations, which were not anticipated in the original regulation. Requirements have been introduced for takeoff runway visual range and visibility minimums to take account of aborted takeoffs or continued flight to specified minimum altitude in the event of critical power failure.

Earlier this year, the ICAO Operations Panel proposed amendments to Annex 6 (including turbine SEIMC flights) that with very little change have been approved by the Air Navigation Commission and the ICAO Council.

The new rule, which is close to the proposed JAA SEIMC wording (but without requirements for available landing sites for overland flights), is scheduled to take effect in November. SETA officials say that the great majority of member states are expected to adopt “something very close” to ICAO wording in revised national standards.