In an airport, especially at night there are so many lighting systems that allow it to operate as efficiently as possible, this include general lighting systems, runway lighting systems, approach lighting systems and last but not least taxiway lighting systems.
in general lighting systems there is an airport beacon mounted or set on top of airport buildings or on towers. it is very strong and has rotating light visible from very far away hence help identify the airport at night.
Beacon usually works by; 2 quick white flashes & green flash for military airport, flashing white & yellow for water airport, flashing white, yellow & green for heliport,flashing white & green for civilian airports.A picture of a beacon mounted on a tower is shown below :-
The runway lighting systems, approach lighting systems & taxiway lighting systems are found along the runway :-
The above image has all lights shown except the PAPI lights as shown below : –
- Run way edge lights – are steady white lights used to highlight or show the pilot edges of the runway at night or during non visibility periods.
- Runway end identifier lights (REIL) – there are two white flashing lights on each side of the approach end of the runway that aid in the identification of the runway i.e from taxiways at night.
- Taxiway edge lights – they are blue in color and are there to help the pilot maneuver his way around the airport
- Runway center line lighting system (RCLS) – they are white lights spaced at fifty foot intervals on the center line of the runway thereafter three thousand feet the white lights change to alternating white and red, and then all red during last stretch of one thousand feet. They are used to designate the center of the runway.
- Touch down Zone lights – this lights are steady white lights placed two rows next to the center line.
- PAPI lights – Precision approach path indicator lights. this are aligned beside the runway and consists of 4 lamp lights on the approach side and aid in glide path. they are designed to show lights either red or white. depending on approach angle, the PAPI lights show either white or red. i.e too high will show all 4 white lights, slightly high 1 red, 3 white lights, correct path 2 white, 2 red, slightly low will show 3 red, 1 white light, too low depicts 4 red lights.
- Approach lights – This lights are set and put as one approaches the runway i.e right before threshold and touch down zone lights. they must all be at same height so in some instances they are put in pedestals . The structural integrity of this pedestals must not be firm in-case of collision with an aeroplane they must give way. This include both center row or side row inset lights.
- Threshold lights – threshold means beginning of the landing portion of the runway and the lights are meant to show this. they light up green on approach side and are put on the beginning of the runway landing and 3m to the end of the runway.
- Guard lights – they are yellow lights deemed necessary in warning both pilots and drivers along the taxiways not to enter an active runway.
- Clearance bar lights – they are inside taxiway and are meant to increase visibility of taxiway intersection or hold line.
- Stop bar lights – these lights are meant to reinforce an ATC clearance i.e cross or enter a runway in low visibility situations hence only installed in a couple of airports. In the situation a pilot is cleared onto the runway, the stop bar lights will be turned off.
- Land & hold short lights (LAHSO) – this are lights in ATC aiding in aircraft landing and holding short of an intersecting runway or specific point on a runway
- VASI lights – Visual Approach Slope Indicators are used both during the day & night and their main use is to aid the pilot with an glide scope angle i.e 3 degrees for small aircraft and a little less for larger aircraft. When Vasi lights indicate 4 white lights you are too high, when there are 2 red and 2 white lights you are in the correct glidepath and when there are 4 red lights you are too low.
ATC – AIR TRAFFIC CONTROL LIGHT GUN SIGNALS
This are gun signals are located at the ATC and are referred to as control tower light gun signals. They flash in different colours i.e red, green & white. They are as follows :-
- Steady green light – This denotes that aircraft on air is clear to land while aircraft on land is clear for take off.
- Flashing green light – This denotes that aircraft on ground is clear for taxi while aircraft on air should return for landing i.e should wait for a steady green light.
- Steady red signal – This denotes that aircraft on ground must stop while aircraft on air should give way to another aircraft and proceed to circle.
- Flashing red signal – This denotes that the aircraft on air must not land while aircraft on ground must taxi clear off runway in use.
- Flashing white signal – This denotes that aircraft on ground must return to starting point on airport while this is never applicable to aircraft on air.
- Alternating green and red – This denotes that both aircraft on air or on ground must exercise extreme caution.