Obstacles to air navigation

Provisions on when setting up an obstacle to air navigation requires an obstacle permission are laid down in section 158 of the Aviation Act 864/2014. 

Determining when you need to apply for an obstacle permission requires considering the distance to and relative position of the nearest aerodrome.

You can check the approximate locations of airports in for example (does not include uncontrolled aerodromes and emergency landing sites).

An obstacle permission is required when the obstacle to be set up:

1. extends to a height of more than 10 metres above the earth’s or water’s surface and is located within a rectangular area around a runway of an aerodrome, light aviation aerodrome or emergency landing site, with the long sides of the rectangle at a distance of 500 metres from runway centreline and the short sides at a distance of 2,500 metres from runway thresholds;
2. extends to a height of more than 30 metres above the earth’s or water’s surface and is located outside the area referred to in paragraph 1, but no farther than 45 kilometres from the reference point of an airport (Finavia, Enontekiö, Lappeenranta, Mikkeli, Seinäjoki);
3. extends to a height of more than 30 metres above the earth’s or water’s surface and is located outside the area referred to in paragraph 1, but no farther than 12 kilometres from the reference point of an emergency landing site or an aerodrome other than an airport (Finavia, Enontekiö, Lappeenranta, Mikkeli, Seinäjoki);
4. extends to a height of more than 60 metres above the earth’s or water’s surface and is located outside the areas referred to in paragraphs 1–3.

Example 1:

Question: Do I need an obstacle permission for my new 20-metre-tall grain silo, which will be built at a distance of 400 metres sideways from the runway centreline of Lapinlahti Airfield?

Answer: Yes. An obstacle permission is needed for all structures that are over 10 metres tall if they are located within a distance of 500 metres sideways from a runway centreline (parallel to the long side of the runway)

Example 2:

Question: Do I need an obstacle permission for my 50-metre-tall new amateur radio mast, which will be built 52 kilometres away from the nearest airport or other aerodrome?

Answer: No. The mast is less than 60 metres tall and is located over 45 kilometres away from an airport.

Example 3:

Question: Does a 40-metre-tall truck-mounted crane that is used to lift prefabricated building elements 20 km away from Pori Airport require an obstacle permission?

Answer: Yes. The crane is located within 45 kilometres of the airport and is over 30 metres tall.

Obstacle permission applications are normally processed with limited resources in the order in which they are received. Applicants are asked to prepare for the processing by submitting their applications in good time.

The processing time depends on the obstacle and work queue, as the processing requires third party statements and potential additional reviews.

The location of the obstacle should be precisely determined before applying for an obstacle permission. In practice, the set-up conditions may vary significantly even in very small areas. If this is the case, the obstacle is allowed to be moved laterally within a radius of approximately 50 metres of the location specified on the application without having to apply for a new permission, provided that the height of the obstacle does not increase and the obstacle is located far away from aerodromes, outside of obstacle limitation surfaces. Such changes must be reported to Traficom with the notification of completion along with the actual ETRS89 geographic coordinates (~WGS84) of the obstacle.

Raising the height of an obstacle beyond the height specified on the obstacle permission is not allowed without applying for a new permission from Traficom.

The height of an obstacle can be lowered from the height specified on the permission without requiring a new permission. The actual height of the obstacle must be reported to Traficom with the notification of completion. 

This paragraph makes it possible to carry out lifting and set up structures over 10 metres tall in an airport area without an obstacle permission from Traficom. However, the lifting must be approved and supervised by the aerodrome operator (Finavia, Enontekiö, Lappeenranta, Seinäjoki, Mikkeli). Even then, the effects of the obstacle on air traffic must be determined first.

If the terms of the obstacle permission mention the need to submit an advance notice for publication purposes, the notice must be submitted before starting the set-up of the obstacle to Fintraffic Lennonvarmistus Oy (lentoesteet@fintraffic.fi) in accordance with the terms of the obstacle permission.

The completion, lowering, removal and change of maintainer of an obstacle must be reported to Traficom at with a separate notice. The notice must include the ID number of the obstacle.

The change of owner or holder of an obstacle must be reported to Traficom at with a separate notice. The notice must include the ID number of the obstacle.

If a permanent obstacle cannot be set up by the date mentioned on the permission, it is necessary to apply for an extension of the obstacle permission from Traficom. The extension must be applied for before the existing permission expires. The processing of the extension at Traficom is free of charge when the old permission is still valid, but if the time for setting up the obstacle mentioned on the permission has expired, the application is treated as a new site and subject to the associated fee. 

As for temporary obstacles, such as cranes, etc., a change in operating time is always considered a new case requiring a new obstacle permission.

If the masts are located outside of an airport area, the bottom 24 metres above ground level can be left unpainted.

White RAL 9003 (in wind power plants, also 7035, 7038, 7047, 9016, 9018)

Red RAL 3024, RAL 3026

Orange RAL 2009

Yellow RAL 1003 (in wind power plants in a sea area also 1023)

The required obstruction lights are specified on the obstacle permission, in the part concerning the terms of the permission.

Obstruction lights are required for structures that

• pierce obstacle limitation surfaces of an aerodrome or are very close to these surfaces
• are in the circling approach area and exceed a height of 45 metres above ground level (the circling approach area is an area within approximately a 10-kilometre radius around an airport)
• are elsewhere and exceed a height of 70 metres above ground level.

The owner of the obstacle is responsible for the maintenance and functionality of the obstruction lights. Obstruction lights cannot be removed without permission. You can ask Traficom about the conditions for removing obstacle lights by sending an email to .

If a tower or antenna structure illuminated by a high-intensity obstruction light in the daytime includes an additional structure that is over 12 metres tall, e.g. a pole or an antenna, at the top of which it is, in practice, not possible to install a high-intensity obstruction light, such a light must be installed as high as possible and efforts must be made to install a medium-intensity obstruction light of type A at the top.

The obstruction light must be visible in all directions so, in practice, one light is not enough because of the blind spots caused by the blades. Depending on the structure, at least two obstruction lighting fixtures that are placed sufficiently far away from each other are needed.

In practice, wind turbines must have at least four intermediate-level lights placed around the tower. At least two lighting fixtures per level must be visible in approach directions.

The light flash frequency of a high-intensity light is 40–60 times per minute.

At present, there are no provisions concerning the emergency power of obstruction lights located outside an airport area.

During set-up work, an obstacle with a height exceeding 70 metres above ground level must be equipped with temporary obstruction lights during the dark part of the day. The obstacle must have at least low-intensity obstruction lights showing a fixed red light in all directions at the top of the obstacle.

When the height of the obstacle to be set up exceeds 100 metres above ground level, the obstacle must also be equipped with obstruction lights at least at one intermediate level during set-up in addition to the lights mentioned in the paragraph above. 

The set-up must be planned so that operations relying on temporary obstruction lights remain as short as possible.

In grouping, low-intensity obstruction lights of type B are used in the inner area turbines.

The maintainer of the obstacle is responsible for ensuring that the visibility and functioning of the obstacle lights correspond to the obstacle permission. Non-functioning obstacle lights and their repair schedules must be immediately reported to Traficom at . 

Provide the coordinates for the centre point of the crane at either end of its movement range, use the additional information field to provide the length and direction of the range and include an attachment, such as a layout plan, that shows the operating range of the crane. The radius of rotation of the tower crane’s jib (the length of the jib) must also be included in additional information.

An obstacle permission is not required for a crane that is working in connection with a fixed obstacle if the height of the crane does not exceed the height of this fixed obstacle.  The fixed obstacle can be a building, mast, wind power turbine, etc.