^{Figure 1: Runways at Helsinki Airport (source: Helsinki Airport Information)}

Helsinki Airport was built in 1952 and later became the largest airport in Finland and fourth largest airport within the Nordic countries. In 2018, the airport handled approximately 21 million passengers and around 350 departures per day. Additionally, the airport hosts 1500 companies and provides 25000 employment positions. The aircraft operate within the two terminals and three runways (Figure 1).

Noise regulations

Based on the Balanced Approach, the Ministry of Transport and Communications had established a working group on noise management at Helsinki Airport. The working group is led by the Finnish Transport and Communications Agency and is composed of the airport, Air Navigation Service Provider (ANSP), relevant ministries, environmental and aviation authorities, regional council, municipalities and major airlines representatives.

Previous Balanced Approach interventions included Continuous Descent Operation implementation, NADP1 implementation for Runway-22L departures, departure route design minimising the noise impact on residential areas and noise level restrictions on certain departure routes. The most typical runway configurations for Helsinki Airport are shown in Figure 2.

In 2017, effective noise abatement strategies for high-weight aircraft were applied. Housing restrictions were redefined in the high noise areas. Departure tracks have been fine-tuned according to the location of suburbs. Noise charges and other economic incentives were implemented to encourage avoiding night-time operations and supporting the use of quieter aircraft types.

^{Figure 2: Most typical runway configurations at Helsinki Airport}

An additional departure runway was required to handle the increased capacity of aircraft departures. The only possible technical solution required more intensive use of the runway RWY-22L, therefore, it would have caused more air traffic and probably a redistribution of the noise exposure. Therefore, the noise level-based departure procedure (ICAO) Noise Abatement Departure Procedure (NADP1) was introduced to prevent more intensive noise exposure for the residents.

Objective

The objective of this case study was to find a solution to increase the departures capacity of the airport without the increase of aircraft noise around the airport.

Approach

This case study describes the implementation of the NADP1 at the airport in order to reduce expected increase in noise exposure to residents from increasing capacity at Runway-22L.

The technical solution to increase capacity required airspace changes, traffic flow changes and the Standard Instrumental Departure (SID) adjustment to avoid certain residential areas better. Because of that, this case represents a useful practice through which operational procedures can be investigated.

1. The departure demand at Helsinki Airport increased during the last years and it was foreseen that the usage of the primary departure runway RWY-22R would reach its limits, especially during the afternoon peak hours between 16:00 h and 18:00 h;

2. An additional departure runway was required to handle the increased capacity of aircraft departures. The solution to increase the departure capacity was to use runway RWY-22L more intensively within already implemented noise restrictions;

3. Until April 2018, only one exit point (DOBAN) was used for the traffic to the south. Increased airplane traffic from RWY-22L that fulfilled the security requirements was enabled by splitting the DOBAN exit point into two separate exit points (KOIVU and VALOX) (Figure 3);

^{Figure 3: Splitting the DOBAN exit point into the two separate exit points VALOX and KOIVU}

4. A change in the noise exposure was expected, so in order to prevent more annoyance, a new NADP1 procedure for all the Standard Instrumental Departures of the RWY-22L was studied. It implied that the aircraft climb higher with constant speed before acceleration is applied – aircraft are flying slower but at the higher altitude. The result is a lower noise level due to a higher flight altitude (Figure 4);

^{Figure 4: The NADP1 procedure enabled a reduction of the noise level due to higher flight altitude and longer noise attenuation distances}

5. The estimated noise levels for departures using runway RWY-22L with standard procedures were compared with the estimated noise levels for the NADP1 departure procedures. Measurements proved that the application of the NADP1 departure procedure resulted in a reduction of the L_max levels of approximately 3 dB. Summing up, the results for decision making were less noise exposure and emissions, less taxi time and air time;

6. The airspace was changed by replacing the exit point DOBAN with two new exit points KOIVU and VALOX. In the same context, the Standard Instrumental Departure (SID) route was adjusted to better avoid certain residential areas. This process was implemented with an active cooperation under the framework of Central Environmental Management group created in 2018;

7. Finally, while checking the success of the new procedures, noise measurements at the Runway RWY-22L confirmed the reduction of noise levels by applying NADP1 as compared to the commonly used departure procedure.

Departures were split up between RWY-22L and RWY-22R led to fuel, time and emission savings due to shorter taxi and flight route distance. The safety and capacity situation at Helsinki Airport improved due to divided traffic flow. The noise exposure was reduced by applying the NADP1 departure procedure.

The greatest difficulty was the actual implementation of the changed operational procedure. The avionics data houses did not recognise the changes at the time when the implementation became applicable. The consequence of that was that the implementation of cockpit charts took extra time and effort. Finavia (the airport operator) implemented a note into their flight preparation software to specify departures from the RWY-22L.

The overall perception of the intervention was positive and worth the effort for the airport and the airlines. There was only a small number of noise related complaints from the nearby residential community. The increased number of flight operations has not significantly increased the annoyance of air traffic noise.