TUIfly aims to cut noise with RNP trial in Hannover

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German leisure carrier TUIfly is testing required navigation procedures (RNP) at its Hannover base with a view to reducing noise for local residents.

The steep, curved approach pattern has been developed by German aerospace research centre DLR to avoid overflying of noise-sensitive areas at low altitude. But it has not yet been approved and thus can only be employed in visual meteorological conditions for the six-month trial.

The idea is to delay the descent before the final approach phase - when the instrument landing system (ILS) is used - and avoid overflying residential areas in favour of, for example, industrial zones. Instead of following a standard, straight ILS approach with a 3° glidepath, the aircraft descends on a 4.5° slope while flying through defined turns with fixed radii (RNP-RF).

The aircraft join the standard ILS approach at a later-than-usual point, 4.6nm (8.5km) from the runway threshold.

Using the RNP-RF procedure, the altitude at which certain residential areas are overflown can be increased by 55% - to 8,400ft (2,500m) - versus a standard ILS approach, says TUIfly. This should in theory lower noise "substantially".

The airline is employing the RNP-RF pattern for landings on runway 27R/09L from both directions. But the plan is to employ the procedure also on the southern, parallel runway during the trial.

If the evaluations are successful, TUIfly hopes to introduce similar procedures at other airports in Germany.