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WHAT DO THE LIGHTS OF THE RUNWAY MEAN?

Who of us, at least once during a flight, has not admired the lights of the runway during the approach to the airport of your destination?
Not only from the windows but, now that the newer airplane models allow it, you can see them directly from the screen placed on the back of the seat in front of us.
I personally never miss a take-off nor a landing: the lights that characterize the runway are like a magnet for the eyes!

But what are they serve for and what do they mean? To identify the runway, you’d say …

And it is certainly correct, but there is much more!
The lights of the runway and, more generally, all the lights of the airport areas have a very precise meaning:  it is are a real code that communicates to the pilot and to his crew a whole range of information.

During the night or when there are conditions of poor visibility, the pilot and his co-pilot distinguish without error all of the zones of the airport and of the various equipment thanks to the different lighting systems of which the airport is equipped.
All the information that during the day is communicated by the signs on the ground, at night and in conditions of poor visibility, they are entrusted to the lighting systems, to the different colours and to their intensity.

Not only the runway itself, but the entire airport is a luminous informational code in addition to the indications provided by Control Tower.

 

APRON AND TAXIWAY

The illumination of these areas indicate to the pilot spaces and limits and are integrated with the instructions provided by the flight controller.

Obviously, the spotlight reflectors serve to provide adequate constant lighting for the taxiing, of all refuelling operations, boarding and disembarkation of goods or passengers and for all of the necessary assistance. But the apron illumination also serves for the surveillance by the security staff that can detect the presence of unauthorized people or vehicles.

The taxiway is bordered by the blue lights along the edges, while the central lines, embedded in the flooring, are green. The latter are also in proximity of the junctions, which permit pilots to identify them immediately.
If we see red lights on the taxiway, it means that we are at a waiting point at an intersection with another runway.

Sometimes yellow lights can be found near intersections with other taxiways. It serves to establish waiting positions that regulate the airplanes real-time transit, excluding any possible interference between them.

 

TAKE-OFF AND LANDING RUNWAYS

The lights of the take-off runway are the real magic in the eyes of the passenger: it is a “catwalk” that accompanies and welcomes airplanes during take-off or landing phases.
To explain in detail, we should write a real flight manual. Therefore, in order to avoid it being boring, we will explain their principle meaning.

The external row of lights delimits the runway, it is white, and the lights are fixed. Sometimes the lights of the last 600 meters are yellow, which indicates to the pilot the approaching of the runway end. And, since, the runway is used in both directions (take-off and landing) the lights are bidirectional – white during landing or take-off and yellow at the end of the runway.

At the beginning of the runway the centreline lights are white, then alternated with red lights in the central part and afterwards becoming all red in the last 300 meters. Obviously, also in this case, the lights are bi-directional.
At the end of the runway, the lights are all red and transversal while those that indicate its beginning are all green. Sometimes, if the airport is near a large city with a lot of lighting that could create potential confusion, intermittent white lights are added to indicate the exact contact area.

But in my opinion the most evocative lights are those related to the glide slope.

These lights are not part of the actual runway, but it anticipates it and allows the pilot, during its final phase, the right approach.
These lights change colour from white to red depending on the position and the altitude of the airplane and based on the perception of colours (in addition, of course, to the indications of the flight controller), the pilot manages to line up properly with the runway.

There are several lighting systems and the main ones are:

 
  • VASIS  (Visual Approach Slope Indicator System)

It consists of 12 lights placed on the ground at the sides of the contact area of the runway forming 4 bars and visually providing to the pilot during approach phase the indications of the optimal descent angle to maintain for the landing. The lights change colour based on altitude and distance, from red, to pink and then to white. When the downwind lights become all white and the upwind lights all red, the airplane can begin the slope.

Consists of 20 lights. 8 of these form 2 bars of 4 lights each, while the others form 2 rows of 6 lights each called Fly-up.
The pilot initially sees the bars and the fly-up lights. As the airplane gets closer, the lights turn white and then the fly-ups disappear. From this moment he can set the slope. If the pilot is in the correct position, he will only see the lights of the two crossbars and will touch the runway exactly in the touchdown zone.

  • PAPI  (Precision Approach Path Indicator)

This system is based on Vasis but it is much more precise, because the colour change excludes pink and it is more clear.
It consists of a single bar of 4 lights arranged, generally, to the left of the runway.
When the aircraft is on the correct glide slope, the pilot sees the two red lights closest to the runway and the other two exterior lights white. If the airplane is slightly high, the light closest to the runway will be seen red and the other three white. If it is very high, the lights will be all white. Conversely, if it is slightly low or too low, the pilot will see the three lights next to the runway – red and one white light, or all red, respectively.

 

APPROACH LIGHT SYSTEM

The Approach Light System allows the pilot to pass from internal instrumental references to external visual references and this lighting system is located at the beginning of the runway.
Obviously, each system varies according to the ILS category (plane system for planimetric survey) in use.
The most used in Europe is known as Calvert and it consists of a row of white lights aligned on the extension of the runway axis for 900 meters, and transversely cut by a series of light bars at regular intervals.
Initially the row of central lights is triple, then it becomes double and finally single when the airplane comes close to the threshold of the runway.
The cross bars, on the other hand, are of decreasing length as you approach them.

Dear readers, we hope to have been able to convey to you some of the magic that surrounds the world of aviation.
Now, for your next flight, you too will see the signal lights of the airport and the landing runway, and you will understand its meaning!

 

That Aviation Italia: passion for flying.

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