Decisions on flight procedures to minimise aviation's impact on an airport local environment must never force safety into second place

Airline chiefs may moan about how tough life is - and recently it has been for many of them. But commercial air transport's main problem for the future - in mature Western-style economies anyway - is the continually growing demand for air travel combined with the infrastructural restraints on the airlines' ability to meet demand.

Flight International predicted many years ago that pressures to introduce environmental constraints on existing services - let alone growth - were going to start hitting the industry in a more organised and relentless form than that to which it had been accustomed. These pressures will continue to accelerate proportionately with time as the lobby groups become more organised, and exponentially with industry growth.

The two forces - demand for travel and pressure to contain its undesirable environmental by-products - create a finely balanced equation. Ultimately, decisions on the balance of the two forces is the stuff of politics, both central and local government. The politicians want to deliver freedom to travel, prosperity, and a quiet environment with clean air. The result has to be a compromise, but that trade-off is weighted differently region by region.

The forces to allow air travel to expand are difficult for politicians to deny because they involve freedom of choice and prosperity. Meanwhile as vast nations like China - with its explosive economic potential - develop, they almost unquestioningly provide their airlines with the infrastructure for rapid air transport growth internally and externally. This raises the pressure to increase trade with them, and that creates - inevitably - an increased need for air travel connections. It is difficult for politicians to resist this if they want their countries to take part in the evolving global economy. Meanwhile, back at home the environmental lobby groups press for air travel containment. These groups cannot be - and should not be - ignored, but some decisions that result from their pressure can be dangerous. This is definitely not the lobby groups' intention, but it can be the result of poorly considered political reaction.

The UK Civil Aviation Authority has just released a sponsored study of international procedures introduced to minimise noise and pollution near airports. Many procedures, especially those initiated a long time ago - and even when adjusted since - never underwent a safety case study before implementation, says report author Professor Peter Brooker of Cranfield University, CAA professor of air traffic management and environmental policy. The result has been that some noise abatement procedures are difficult to fly, or increase pilots' workload to a point where they could become distracted from the main task of handling the aircraft safely. Any procedure that has not been subjected to safety case study must now undergo it, advises Brooker. On the whole, however, Brooker does not find that most environmental procedures like noise abatement take-off procedures, noise preferential routeings, and continuous descent approaches represent a significant increase in safety risk.

But there are two areas where Brooker says there is real cause for concern: the allocation of runways for environmental rather than safety reasons, particularly when aircraft are required to land with tailwinds or crosswinds at an airport where there is a choice of an operationally more suitable runway; and most dangerous by far, requiring an aircraft to use a runway which has a non-precision approach (NPA) at night or in instrument meteorological conditions when there is a suitable runway available with a precision approach aid. Forcing the use of non-precision approaches solely for environmental reasons should simply not be done, says Brooker, because the accident risk increases by a factor of 8.5 for an NPA compared with a precision approach. The mathematics are derived from real accidents.

When Brooker looked into the national laws on which the UK CAA is required to base its environmental procedure judgements, he found that the agency is told unequivocally to rank safety as the paramount consideration. That is also what the International Civil Aviation Organisation says and what the European Joint Aviation Authorities require. All government directives to their aviation agencies should specify safety as the top priority when environmental and safety issues clash. When incremental risk factors like 8.5 are at stake, either the environment has to take second place or aircraft should be required to divert rather than carry out the approach. A crash that killed 24 people on an unnecessary NPA in Switzerland in 2001 is testimony to that.

Source: Flight International