Imagine the ramifications of this headline: 'Very light jet collides with Airbus A380 over London' - the story reveals that the VLJ was flown by a single pilot holding a Private Pilot's Licence with a current instrument rating and 250 hours total flying experience, who had satisfactorily passed the necessary ground and flying tests to achieve a rating on the type of VLJ he was flying. The VLJ was not equipped with a Traffic Alert and Collision Avoidance System (TCAS/ACAS): under the present regulations the VLJ would have been operating perfectly legally.

Concern has been voiced in some aviation committees, and the national press, over VLJ aircraft operating in the same airspace as commercial and similar air traffic but without the safeguard of a TCAS. At present there is no requirement for aircraft under 5,700 kg maximum take-off mass to be fitted with TCAS, but Eurocontrol has for some time made it known that a study is to be undertaken to assess the impact of VLJs on the network and evaluate the risks and safety issues of such aircraft as VLJs operating in European airspace.

Now that Mode S transponders are a mandatory fit for operations in European airspace it can be argued that it is not necessary to fit TCAS to a VLJ as a TCAS II equipped aircraft will be able to receive the signals from the Mode S transponder and take appropriate avoiding action. This can be done without the non-TCAS aircraft being aware that it is causing a possible conflict. However what is worrying is the case that if this non-TCAS aircraft does see the other it could take action that would put it in more danger due to not knowing the intent of the TCAS II operator.

The fitting of TCAS I, a cheaper alternative to TCAS II, would not really solve the problem as TCAS I only produces traffic alerts and not resolutions. This again could put both aircraft in danger if action was taken on the traffic alert without knowledge of the other aircraft's intention.

An argument for not fitting TCAS to VLJs is that if they are single pilot operated, the pilot will have enough work to do with the complexity of avionic equipment that is installed, without the additional burden of TCAS alerts. This is negated by ensuring that a pilot who intends to operate in the congested skies of Europe and elsewhere is properly trained and in practice on all the equipment that is fitted to the VLJ that he is to fly.

It would go a considerable way to assuaging the concerns of operators and crews who regularly use congested airspace if all aircraft within that airspace were fitted with TCAS II for safety purposes. Original Equipment Manufacturers should make provision for the fitting of TCAS II to VLJs so that the customer has a choice of fitting the equipment or not. If he does he will not only help to reduce the risk of a mid-air collision, so enhancing flight safety, but will also add value to his aircraft for resale purposes.

It matters little what size an aircraft is if it does collide with another, it will be still be a catastrophe. Every effort should be made to ensure that the skies are as safe as possible and if this involves fitting the appropriate available equipment then it should be done.

Comment by John B Robinson, operations consultant to the British Business and General Aviation Association