Swiss air traffic controllers are to impose temporary capacity reduction at Zurich airport, in order to implement a new airspace structure which has been based on collision-risk modelling.
The redesigned airspace – intended to minimise infringements – will come into effect from 20 March.
Swiss air navigation service Skyguide will reduce Zurich arrival capacity by 20% for four weeks, and also restrict general aviation activity in the vicinity of the airport.
The redesign features changes such as a revision of terminal airspace zones. It covers not only Zurich but the military airspace around Dubendorf airfield, and also involves adjustments to gliding areas.
Skyguide says the “far-reaching” change is the largest to the airport’s airspace in “several decades”, but adds that it is “committed to minimising the impact”.
The redesign has been spurred by a number of airprox incidents at Zurich but, in particular, a serious occurrence in March 2011 when two Swiss Airbus A320s were cleared for take-off on intersecting runways within 46s of one another.
As the jets accelerated, the crew of the A320 on runway 28 – having seen the other A320 converging from runway 16 – aborted the take-off at 135kt. The abort was initiated 550m before the runway intersection and just as the other aircraft was lifting off at 162kt.
Swiss investigators stated that the situation involved a “high risk” of collision. The inquiry found that the airport’s complex operation on intersecting runways was subject to only “a small error tolerance” during periods of high-volume traffic.
The Swiss federal civil aviation office launched the airspace redesign process in 2018, intending to simplify the structure in order to improve safety.
“This is the first time in Europe that the airspace structure around a major commercial airport has been redesigned based on collision-risk modelling,” the office claims.
It states that the airspace in the vicinity of Zurich handles some 300,000 annual aircraft movements, and has three control zones and 17 local control districts.
“Airspace violations occurred regularly,” the office adds.
It says the redesign has been founded on a target level of safety – set at a one-in-1 billion probability – to protect scheduled flights, with calculation of collision risks in relation to approach and departure procedures.
“Based on these results, the extent of the respective airspaces was adjusted until the specified safety limit could be met,” it states, adding that these limits are maintained when taking into account military and general aviation requirements.
No noise impact will arise from the new airspace structure, the office says, with the approach and departure routes remaining unchanged.
Skyguide says its capacity-reduction measures will give air traffic controllers and pilots time to adjust to amended routine, reducing the risk of “system overload”. It adds that it will continually evaluate the extent to which it needs to keep the measures in place.
