According to Eurocontrol, by 2010, European operators will have ordered some 500 very light jets (VLJs) and about 300 of these will have been delivered by then, with most of them being destined for air-taxi services. The agency’s initial assessment indicates this new generation of business jets will have a significant impact on Europe’s airspace and Eurocontrol is studying the case for mandating TCAS II traffic alert and collision avoidance systems for all VLJs.

The agency’s Trends in Air Traffic study of business aviation, released in May 2006, estimated that by 2015 the number of business jets (including VLJs) in Europe would be 500 to 1,500 greater than it was in 2004. More recent projections, however, see just over 500 VLJs in Europe by 2010. Cessna has already started delivering its new Citation Mustang on this side of the Atlantic and at least 14 are already in service (registered in Germany, the UK, Austria, Spain, Denmark, Netherlands, plus several U.S.-registered aircraft based in the UK).

The Eurocontrol figures suggest that around 100 VLJs could be delivered to Europe each year through the end of 2010. If this rate is sustained it would result in the number of VLJs in the region totaling about 700 by 2015.

What is not yet clear is how many of these VLJs will replace older, more expensive aircraft. Since many of the operators are startups planning new business ventures with these aircraft, the extent of direct replacement is assumed to be relatively low. However, there is likely to be some indirect replacement, where the new aircraft force out current models. In that scenario, it is widely assumed that the VLJs will replace older turboprops.

Currently, daily use of business aircraft varies widely, from two flights per week on average for a corporate flight department, to five weekly flights for charter operations and as many as three daily flights for more intensive users (including positioning flights). Forecasts of future volumes of VLJ flights are therefore contingent on the assumptions made about how they will be used. Nevertheless, most of the orders placed to date appear to be for air-taxi type operations, such as those flown by Bikkair, London Executive Aviation, JetBird and Blink.

Taking these assumptions, one can arrive at a rough estimate that VLJs will fly up to 300 additional flights daily each year in European airspace; that is, 100 additional aircraft flying three flights per day. This is an upper estimate, as the two main variables could reduce this total. The first variable would be the delivery schedules, which for new aircraft types are more likely to be delayed than to be advanced. Second, the estimate is based on the optimistic prognosis that the new air taxi services will be an instant success.

To put this growth in context, Eurocontrol’s figures indicate that all business aircraft in Europe flew about 200 more movements each day in 2007 than in 2006. This is already a significant portion of the total growth in European traffic–now running at about 1,500 additional movements each day–but the current thought is that VLJ deliveries are likely to drive this number higher.

To ensure that the increase in VLJs entering operations in European skies over the next five to 10 years is handled safely and efficiently, Eurocontrol’s European VLJs Integration Platform (VIP) is assessing solutions for integrating VLJs into the European air traffic system. In addition to the European Business Aviation Association, several VLJ manufacturers and operators are participating in the VIP process.

Eurocontrol is also preparing a real-time simulation that will assess the impact of VLJ operations on the European ATM network. The simulation is scheduled to be conducted in Budapest in October.

An initial comparison of published VLJ performances shows that for some of the phases of flight, VLJs will have very different speeds and cruising altitudes than commercial jets. For that reason, it is likely that VLJs will have a considerable impact on the network during at least the takeoff and en route phases.

Eurocontrol also is analyzing the technical requirements for onboard systems, as it may be difficult to adapt particular navigation requirements into some of the fully integrated avionics systems currently installed in certain VLJs.

In Europe, the installation of  TCAS II equipment to reduce the risk of midair collisions was mandated in two phases: starting in January 2000 for aircraft with a max takeoff weight above 15 metric tons (33,068 pounds) or carrying more than 30 passengers; and beginning in January 2005 for aircraft with an mtow above 5.7 metric tons (12,566 pounds) or carrying more than 19 passengers. Now Eurocontrol is posing the question as to whether safety benefits would derive from extending the use of TCAS II to very light jets; that is, aircraft weighing below 10,000 pounds mtow.

Eurocontrol’s AVAL project is trying to answer this question. The study is being carried out in two phases, with the final analysis to be completed in 2009. The findings of the first phase indicate that TCAS II provides safety benefits to equipped aircraft, as well as the entire airspace system, and works better when both VLJs and light jets are equipped.

Furthermore, there is evidence that the new VLJs and other small light jets will have an effect on the overall performance of TCAS II as a safety net. If they are not equipped with TCAS II, they will not benefit from the safety aspects of the system, and may also have an impact on the safety of TCAS II-equipped aircraft. However, the report indicates the safety benefits derived from an extended TCAS II mandate need to be quantified.

Additionally, the report stresses that pilot’s response to TCAS II resolution advisories will be an important consideration and that pilots need to be trained carefully in the operation of the collision avoidance system. Among possible realistic scenarios would be a new mandate with a target date of 2015.