International law relating to aircraft noise has recently been clarified. It must be used to terminate an unfortunate German/Swiss dispute

A dispute about aircraft noise on the main approach to Zurich airport, Switzerland, is going to be an interesting test of inter-state goodwill within Europe and respect for international law as it relates to aviation.

Zurich's Kloten airport is within 15km (9nm) of the German border, and the extended centreline to its main landing runway - 14 - happens to cross the closest point on the frontier. The dispute is about aircraft noise, and the citizens of southern Germany have been backed up by a German court in their contention that they should not have to endure the noise of aircraft using a Swiss airport.

This is a use of the sovereignty card, which is traditionally used relative to airport approaches only when a country does not recognise the state it borders with. Gibraltar is an example, with its citizens resolute in their Britishness and the territory claimed by Spain. Aircraft using Gibraltar's airport have not been allowed to infringe Spanish airspace, which means tight turns on some approaches or departures. But recognition is scarcely an issue between Germany and Switzerland. The border between the two countries is open and there is free movement of labour.

Germany has not yet banned flights approaching runway 14, but it has tightened an already demanding curfew and the Swiss have complied. The dispute has now reached government-to-government level since the Swiss federal parliament declared its belief that the restrictions are illegal. The noose really tightens, however, from 10 July, when Germany intends to ban approaches even outside the curfew unless visibility conditions are so bad that the instrument landing system approach to runway 14 is the only option for inbound aircraft.

These unilaterally imposed rules contravene the International Civil Aviation Organisation Chicago Convention in the letter and the spirit. What is more, this principle has recently been reinforced by an ICAO ruling on a disagreement between the USA and the European Commission on noisy aircraft. Europe was going to stop aircraft hushkitted to Chapter 3 standards being introduced on to the European register because they meet the specifications by only a slender margin. The USA, whose industry produced most of the aircraft affected, won the argument against the proposed EC action when it took the case to ICAO, and Europe had to climb down.

However understandable the EU's intent, its action ran counter to the principle that, in aviation, which is international by its nature, the world has to establish what acceptable international operating standards are and stick to them until they are changed by consensus at the appropriate forum - in this case ICAO. Certainly states cannot dissent from the noise standards in the treaty, although there is a provision for local rules to be tightened for good reasons if all other means of ameliorating the situation have been exhausted. In this case, however, the situation is international whether the citizens of southern Germany like it or not.

It is, nevertheless, relevant to consider whether the Swiss have followed ICAO guidelines to reduce Zurich airport noise or its effects. Before local restrictions can be put in place, says ICAO, three measures must have been tried: introduce quieter aircraft; ensure that dwellings are not built under existing approach or departure paths; and operate noise abatement procedures or fly into the runways that have the fewest people living under their approaches. Zurich airport has a per-aircraft tariff that increases according to an aircraft's noise footprint; it operates noise abatement procedures; and runway 14's approach passes over the least populous land. In fact, by compelling Zurich to use alternative runways, Germany is forcing approaches over more populous areas. The part of southern Germany under the 14 approach is sparsely populated, hilly, mainly agricultural land.

Meanwhile, safety inevitably enters the equation. The most dramatic example is a November 2001 accident involving a Crossair flight planning a runway 14 ILS approach. It was re-routed on to a non-precision approach to runway 28 because the 22:00 curfew had just come into effect. It crashed on final approach, killing 24 people. It would be wrong to say that the runway change was the cause of the accident, but it can be said with near certainty that the accident would not have occurred had the approach to 14 gone ahead.

Rulings so far have been made at German courts, but this is an international issue. The German government must assume responsibility here and abide by international law.

Source: Flight International