What can pilots see at night – and what's the point of those headlights?
Andrew Mccoy Anyone who has ever star-gazed will know that aircraft use lights when flying, pesky planes masquerading as shooting stars throughout the hours of darkness.
But the powerful LED spotted from the ground, 35,000 feet below, is not a headlight, guiding the path of the 8.30pm service to Chicago; more likely a beacon to help other pilots spot the plane in the air. At altitude, planes do not use headlights in the traditional sense.
“Many times when I am making oceanic crossings at night, there is nothing outside the windshield but blackness for hours on end,” says pilot and flying instructor Tim Sanders.
“As pilots learn the art of science and flight, we have to make a transition to using our flight instruments, navigation sensors and weather sensors (primarily radar) to substitute for normal vision during night or other times when in cloud.”
Do planes have headlights?
Though aircraft do not have headlights in the traditional sense, they do have a plethora of illuminations, each performing a different function.
The lights closest to those we might have on our cars or motorbikes are the landing lights employed by the flight deck on approach to an airport. They are positioned in different places on different aircraft, from the wing to the fuselage.
These not only help the pilot land at night but also make the aircraft more noticeable to anyone in the vicinity. To become yet more conspicuous some pilots will flash their landing lights on final approach or when they have deployed their landing gear to let the air traffic control tower know.
Other lights on an aircraft include red and green LEDs on each wing to indicate to other aircraft at night which direction the plane is facing - green right, red left. There are also anti-collision beacon lights on the top and bottom of the fuselage that rotate reddish orange to produce a flashing effect. These are turned on as long as the plane’s engines are running.
How powerful are plane lights?
Lighting experts Oxley, a company which began life producing capacitors for the military in the Second World War, today serves all sorts of aviation clients with the lights needed for a modern aircraft.
Among them are landing lights able to operate in temperatures from -54C to 71C. Their peak intensity is 600,000cd - that’s 600,000 candela, offering about 600,000 the luminous intensity of a single candle.
“Most of us think of airports as quite well-lit places, and it’s true that the apron areas around the terminal buildings are often brightly illuminated,” writes Mark Vanhoenacker in his book How to Land a Plane.
“But taxiways and runways are so subtly lit that picking out an airfield at night, especially in an urban landscape often involves looking for a particularly dark spot. Close in, thankfully the approach and runway lights are unmistakable.”
What can pilots see from the cockpit?
Given that they are often operating above the cloud in near-absolute darkness, one might think that the view from the cockpit is not up to much.
But according to US Air Force turned commercial pilot Ron Wagner, there is plenty to look out for.
“On clear nights going east somewhere around Oklahoma City and Tulsa I have seen the lights of Dallas (180 miles) and Houston (420 miles) in one direction and Kansas City (300 miles) and St Louis (460 miles) in the other direction, all at the same time,” he said.
Beyond the city lights laid out below, pilots also get a front row seat to weather phenomena, from storm clouds and lightning to the Northern Lights.
“Speaking of things that gave me the creeps in jet cockpits at night was when we got St Elmo’s Fire dancing all over the windshield,” said Wagner.
“Sometimes it would come into the cockpit and dance on the glare shield. Despite being a smart guy with an aerospace engineering degree, St Elmo’s Fire always creeped me out. Something in my unconscious gets weirded out at the sight of dancing electricity at night.”
Wagner also spoke of witnessing “the infamous and elusive green flash”, a verdant blip that occurs at the moment the “last tiny dot of the sun” disappears over a crisp, clean horizon, rarely visible from the ground.
Pilots sometimes pass other planes, too, a few thousand feet apart.
What happens when pilots cannot see anything?
Pilots are trained to perform “instrument landings” when they execute an approach and touch-down in minimal visibility, most often thanks to extreme weather, using only the information and positioning delivered on screens in the cockpit.
Airports also help, providing an Instrument Landing System (ILS), where pilots lock onto a landing beam emitted from the runway.
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