Definition of Obstruction Light
A light indicating the presence of an object which is dangerous to an aircraft in flight. The obstruction light is to be mounted at the highest point of the wind cone assembly to avoid being obscured by any other part when viewed from above.
Types of Obstruction Lights
Obstruction Lights are broadly divided into three following parts–
•Low Intensity Obstruction Lights: These lights should be used where the object is a less extensive one and its height above the surrounding ground is less than 45 m.
Medium-Intensity Obstruction Light
• Medium Intensity Obstruction Lights: Medium Intensity obstacle lights should be used where the object is an extensive one or its height above the level of the surrounding ground is greater than 45m.
• High Intensity Obstruction Lights: These lights should be used to indicate the presence of an object if its height above the level of the surrounding ground exceeds 150m. According to ICAO regulations Obstruction lights are divided in following types.
• Low Intensity – Type A: Red color steady lights are used for fixed obstacles. Their minimum intensity should be 10 candelas.
• Low Intensity – Type B: Red color steady lights are used for fixed obstacles. Their minimum intensity should be 32 candelas.
• Low Intensity – Type C: These Yellow/Blue color flashing lights are used for mobile obstacles. Their minimum intensity should be 40 candelas.
• Low Intensity – Type D: These Yellow color flashing lights are used for “Follow me” Vehicles. Their minimum intensity should be 200 candelas.
• Medium Intensity – Type A: White color flashing lights are used for obstacles having height more than 45 meters. Their minimum intensity should be 2000 candelas.
• Medium Intensity – Type B: Red color flashing lights are used for obstacles having height more than 45 meters. Their minimum intensity should be 2000 candelas.
• Medium Intensity – Type C: Red color fixed lights are used for obstacles having height more than 45 meters. Their minimum intensity should be 2000 candelas.
• High Intensity – Type A: White color flashing lights are used for obstacles having height more than 150 meters. Their minimum intensity should be 2000 candelas.
• High Intensity – Type B: White color flashing lights are used for obstacles having height more than 150 meters. Their minimum intensity should be 2000 candelas.
Where Will Require Aviation Obstruction Lights And How Many Will Be Used?
Need of Obstruction Light
Any structure in a flight path or even a structure which in height is 150mtr or higher, requires visual marking with aircraft warning lights.
Number of Obstruction Light
Number of obstruction lights to be placed on tall structures can be calculated by the following formula –
• Number of Lights = N = Y/45 Where Y is the height of the Obstruction.
• Light spacing = X = Y/N <= 45m There should be atleast 45 meter gap between two obstruction lights installed on tall structures
Obstruction Light Selection for Vertical Structures
|
ELEVATION |
MARKED |
Low Intensity Obstruction Light Type – A/B |
Medium Intensity Obstruction Light Type – A |
Medium Intensity Obstruction Light Type – B/C |
High Intensity Obstruction Light Type – A |
|
<45m |
YES |
only night |
|
|
|
|
<45m |
NO |
only night |
|
|
|
|
>45m <105m |
YES |
only night 1 |
|
only night 2 |
|
|
>45m <105m |
YES |
|
only night |
|
|
|
>45m <105m |
NO |
|
day night |
|
|
|
>105m <150m |
YES |
only night 1 |
|
only night 2 |
|
|
>105m <150m |
YES |
|
only night |
|
|
|
>105m <150m |
NO |
|
day night |
|
|
|
>150m |
YES |
only night 1, 3 |
|
only night 2 |
|
|
>150m |
YES |
|
only night 3 |
|
|
|
>150m |
YES |
|
|
|
day night 4 |
|
>150m |
NO |
|
day night 3 |
|
|
|
>150m |
NO |
|
|
|
day night 4 |
1.Lower Level
2.Upper Level
3.More Than one level (Distance between levels 52m maximum)
4.More Than one level (Distance between levels 75m maximum)
Post time: Jun-15-2019
