Recently, I thought I lost my favorite flashlight. It is a Smith & Wesson with the ability to project a white, red, and green light. It is my favorite to bring along in the airplane because it provides illumination for the preflight as well as illumination in the cockpit in the event the panel post lights fail.
Also, it was the last Christmas present my father gave me before he flew West—and flashlights were very, very important to my father.
Dad was known for his flashlights. When someone in the neighborhood needed a giant floodlight, a flashlight with an angled head, one with a magnet in the base or a clip that allowed you to work hands free—they came to him. With this in mind, it’s easy to understand the drama created when I forgot my flashlight on a Girl Scout camping trip when I was nine. From the way the troop leaders reacted you would have thought I had defected to the Campfire Girls. How in the world could my father’s daughter forget her flashlight? I swear the event traumatized me, because since that day forward, I have never been without a working flashlight. This is a personality trait that has served me well as a pilot.
Flashlights and Pilots
How many flashlights do you carry in your flight bag? There was a time when it was recommended that a pilot carry two for night flight: a D-cell battery-operated version with a white lens for preflight inspection, and a flashlight with a red lens for cockpit illumination at night. Understanding how the human eye works was and is part of a pilot’s education.
Because of the particular physiology of the eye, humans have diminished visibility in low-light situations. (You can find the details in Chapter 11 of the FAA’s Airplane Flying Handbook.)
Light from an object enters the eye through the cornea and the pupil. The pupil either expands or constricts, controlled by the colored part of the eye known as the iris.
The lens of the eye is located behind the pupil and its function is to focus light on the surface of the inner layer of the eyeball known as the retina.
The retina contains photosensitive cells called rods and cones. The cones are in a higher concentration than rods in the central area of the retina known as the macula. The exact center of the macula has a very small depression called the fovea, which contains cones only.
The cones are used for day or high-intensity light vision. They are involved with central vision to detect detail, perceive color, and identify far-away objects.
The rods are located mainly in the periphery of the retina—an area that is about 10,000 times more sensitive to light than the fovea, so the rods are more useful for night vision.
It can take up to 30 minutes for a person’s eyes to adjust to low light situations.
For pilots, losing night vision during a flight could be dangerous—so keep the white lights out of the cockpit. Instead, use a flashlight with a colored lens such as red, green, yellow, or blue to protect your night vision.
Unfortunately, some pilots seem to be missing that, as I have seen private pilot candidates attempting to use their cellphone light in the darkened cockpit because the illumination provided by the post lights wasn’t enough. Please don’t do this, as not only do you destroy your own night vision but also that of the instructor sitting next to you. At least warn the person sitting next to you so they can cover one eye and look away to preserve their night vision.
Colored Light in the Cockpit
For decades, red light was the most common color used in cockpits. Around 2010, there was a move away from red light in the cockpit during night flight to green illumination, as many pilots found they had better visual acuity under green light. Blue and yellow lenses are also available if they work better for you—it pays to experiment.
Many aviation flashlights have the ability to project light in multiple colors. Figure out which one works best for you, and when you activate it, keep the lens pointed down just in case you make a mistake and activate white instead of the color you intended to use.
The Right Angle Flashlight
A flashlight with an angled head is one of the most useful designs—it can be set on end and used hands free, or in the cockpit, it can be strategically placed down the front of a polo shirt or locked in with the shoulder harness to illuminate the cockpit panel. The price of these J-shaped flashlights varies from around $10 to $70 depending on the size and materials used. Most come with multiple-colored lenses. Fair warning: Lower price can mean lower quality. They are made of plastic, and plastic is not terribly forgiving when it gets dropped, nor does it protect the interior of the device. The contact points inside the flashlight body are what usually fail, and often they are difficult to repair or replace.
When shopping for a flashlight, note the batteries required. If the batteries are not easily acquired, you may want to think twice, as you should always carry replacement batteries with you in your flight bag. Either keep the batteries in the original packaging or with tape over the contact points to avoid accidental arcing if the battery encounters a loose piece of metal—like a key—in the gear bag.
Most batteries are rechargeable—but they will never go back to 100 percent. An overcharging battery can lead to a thermal runaway and fire, especially if you opt for off-brand cheap batteries not recommended by the manufacturer. Off-brand cheap batteries can also corrode or split, resulting in damage to the flashlight. When a battery goes critical or oxides, it is pretty much the end of the flashlight. Stick with name-brand batteries for best results.
Hand Crank Flashlights
Some flashlights don’t need batteries at all. Hand crank flashlights utilize a circular crank or a squeeze handle to spin a flywheel inside the flashlight that is attached to a small generator/dynamo. This supplies electric current to an incandescent bulb or LED bulb.
Hand crank flashlights work great in an emergency or when batteries are not available. The downside is that they may not hold power very well. Before use the flashlight needs to be cranked for a few minutes in order to be used effectively. Cost: $10-$27.
The cousin of the hand crank flashlight is the shake flashlight. The power for the LED is generated through the movement of a magnet through a coil of wire in a tube. As the magnet moves through the coil of wires it generates a pulse of electricity and there is light. A shake of about 30 seconds —like you are mixing up a beverage—to a minute provides power for about 20 minutes. Cost: $10-$33.
Rechargeable flashlights are a greener alternative. You can have the best of both worlds with a rechargeable LED flashlight. When not in use they plug into the wall and achieve charge via a micro-USB. There is an LED indicator that displays the battery level and warns you when it is running out of juice. Cost: $80+.
Does Size Matter?
The size of the flashlight — be it AAA, AA batteries, or D or C cell — doesn’t really make a difference, because with the invention of the LED (light emitting diode) and the adjustable beam even the smallest device can project a great deal of light.
While smaller flashlights are easier to carry in your flight bag or jacket pocket, they are also easier to lose. For that reason you may want to go big—such as with the traditional D-cell design.
My first pilot flashlight was a two D-cell flashlight Maglite. I still have it—it is heavy and on the larger side as it is similar to the ones used by law enforcement. Over the years I have found it most useful for illumination and a few times it doubled as a defensive tool, I mean, I swung that thing like it was Excalibur.
And about the flashlight I thought I lost? I found it under the lining in the trunk of my car. It must have fallen out of my gear bag. I celebrated as only my family does in these cases—by buying another flashlight.