According to a study by UK research contractor Qinetiq for the European Aviation Safety Agency (EASA), commercial air transport flights by single-engine aircraft in instrument meteorological conditions or at night (SE-IMC/night) should not be prohibited automatically. That is the good news for proponents of SE-IMC/night operations who have been seeking the clearance for more than 20 years. The bad news is that further public comment likely will be required and EASA has not yet scheduled the necessary rulemaking process.

The agency inherited responsibility for considering commercial SE-IMC/night flights from Europe’s now-defunct Joint Aviation Authorities (JAA), which failed to resolve arguments between the industry and national regulators. Individual countries–including Australia, Canada, the U.S., and European Union states such as Denmark, Finland and Norway–have adopted rules that permit commercial SE-IMC operations under specified conditions, and the International Civil Aviation Organization issued SE-IMC operating standards in 2005.

Roughly equivalent to flights under U.S. single-engine instrument flight rules, such operations might have been possible in Europe in early 2010 had EASA accepted without question data used previously by JAA concerning similar operations in other regions. However, approval seems now to have slipped at least 12 months.

According to EASA, the Qinetiq report has concluded that there is “no need for a blanket [SE-IMC] prohibition,” rather it recommends additions to EASA’s earlier notice of proposed amendment (NPA) to implementation of flight rules. Now the agency–whose staff is facing a mounting workload as they assume new responsibilities for aircraft operations and pilot certification–intends to publish the report at an unspecified date, but has not issued any rulemaking proposals.

EASA is currently drafting the implementation rule, which involves transfer of existing commercial air transport operations legislation. SE-IMC/night operations will be a separate rulemaking task after the agency issues its “opinion” on the initial implementation rules. [Opinions are draft legislation sent to the European Commission for further process by the Commission, or the Council of Ministers and the European Parliament, before enactment. Any new legislation would be an amendment to the EASA Basic Regulation and its implementation rules.–Ed.]

The agency will not finalize plans for the 2009 rulemaking until the end of this year, until it has determined priorities after discussions with two regulatory and industry consultative bodies–the Advisory Group of National Authorities and the Safety Standards Consultative Committee.

This procedure suggests that approval might not come before 2011, since additional public comment would be needed if EASA accepts the Qinetiq study, which is reported to include the recommendation that SE-IMC/night operations always require two crewmembers.

Industry aspirations to fly fare-paying passengers in single-engine aircraft in instrument conditions or at night have had a long tortuous history, with some European regulators–particularly the UK Civil Aviation Authority–adopting a very conservative approach. These officials may have been encouraged by EASA’s rejection of earlier industry arguments supporting of commercial SE-IMC clearance and by the as-yet-unpublished Qinetiq recommendations for an apparent tightening of planned requirements. The agency also said some of the safety data accepted by the JAA related to equipment or conditions not representative of operations in Europe.

Industry lobbyists, representing both operators and manufacturers, had hoped to persuade JAA safety officials to support commercial SE-IMC/night operations with so-called “risk periods” of up to a cumulative 15 minutes in any flight. For example, one idea was to allow for the possible loss of engine power while the aircraft was outside the still-air gliding range of undefined alternative landing areas.

Britain’s CAA was strongly opposed to that concept, saying it did “not accept the concept of an in-flight ‘risk period.’” When challenged by a Cessna Caravan I sales agency about just how much better single-engine safety had to be for SE-IMC/night approval to be granted, the CAA responded that the level of acceptability was not tied to “any particular fatal-accident rate.”

EASA contracted the Qinetiq study, saying the firm should take into account “all the risks,” considering, if necessary, additional sources of safety data. As planned 12 months ago, the report, submitted on time last October, might have permitted EASA development of new operating rules to begin in late 2007 or this year.

Before EASA inherited the SE-IMC/night controversy, two successive JAA working groups had prepared draft regulations to replace national rules. They circulated myriad proposals for member states’ comments, but they could not achieve a consensus on a draft final rule.

EASA officials had hoped to adopt such a rule as the basis for its own proposed regulation– which unlike JAA rules would be mandatory–but lack of agreement within JAA and arguments against a supporting regulatory impact assessment (RIA) prompted the new research.

The agency concluded that some objections to SE-IMC/night operations (see box)–particularly those against the RIA–“might be valid” and suspended planned rulemaking in favor of a “full and objective” assessment for each phase of proposed commercial SE-IMC/night operations. “It is necessary to identify all the risks and possible mitigating factors assuring that SE-IMC operations do not involve more risks than multi-engine IMC operations,” the agency concluded.

Qinetiq was specifically required to review existing reliability data, using the results of JAA reports, and particularly to verify that data was “statistically valid, balanced, applicable to the airplanes expected to be used in [European] SE-IMC operations, and reflects the specifics of the European region.”

Where data did not meet these criteria, Qinetiq could use additional sources to complement and/ or update existing information with new data. The contractor considered reliability of modern engines, including risk periods and their impact on safety, and the new ICAO requirements adopted into the Annex 6.   

SE-IMC Operations Challenged

In the process of determining whether to allow commercial air transport flights by single-engine aircraft in IMC, the EASA contracted Qinetiq to study the risks. Before receiving the company’s report, the agency listed the following concerns about such operations:

• the concept of “risk periods” on departure and during cruise where there is no available “landing site” provided insufficient safety;

• specifications for a “landing site” and requirements for its availability and physical inspections were insufficient and did not provide enough safety;

• operations over densely populated regions might be unacceptable;

• reliability data on accidents/incidents involving SE-IMC operations that was based on U.S. data was considered unbalanced and incomplete;

• a prevailing percentage of operations with a single airplane type (Cessna 208 Caravan I) was not representative of potential European operations;

• U.S. data did not reflect specific European conditions, such as population density and lack of suitable landing sites in certain European regions; and

• composition of the JAA working groups preparing the commercial SE-IMC notice of proposed amendment did not have balanced supporters and opponents.