Flashlight User Interface2016-12-12T14:15:05-05:00

Tactical Flashlight User Interface

by David Barnett, P.E.

One of the most critical features setting apart a tactical flashlight from the non-tactical variety is its user interface. Simply put, a user interface is the method by which the operator of a device controls its functionality. In the case of a flashlight, it refers to the manner of turning the light on and off and, if applicable, changing modes of operation.

A tactical flashlight, when properly designed, must provide reliable control when the operator is under high stress and in adverse conditions. A tactical flashlight must provide simple and intuitive operation when the user is mentally, emotionally, and physiologically overloaded. Under high stress, cognitive reasoning gives way to instinctive response, and fine motor skills degrade to brute force. These factors demand that any tool be exceedingly simple in its operation and extremely robust in its design.

Binary controls provide the most reliable systems since human reaction time increases exponentially as options increase. A binary control provides only two options (On or Off, for example). When more than one function must be regulated, the functions should be decoupled, or separated, into binary controls. Imagine the folly of an automobile with one pedal replacing the brake and accelerator (press once to accelerate, press three times and hold to brake)!

While the idiocy of a one-pedal car is apparent, many so-called “tactical” flashlights on the market use an equally inappropriate user interface. Flashlights with multi-click operation are commonly marketed as “tactical” yet use a single button to control, not only On/Off, but multiple mode selection as well. These flashlights fail to incorporate binary operation and also fail to decouple various functions. Such flashlights are wholly unsuited for tactical operations.

Multi-click user interfaces are exceedingly common, not because they perform well, but because they are cheap to manufacture. All LED flashlights contain a “driver” circuit. This circuit can be programmed to provide as many modes as desired without adding any cost to production. A manufacturer can add strobe, variable output, SOS, disco, programmability, or any number of gimmicks absolutely free so long as one button controls everything.

As many can attest, what looks impressive in the showroom does not play so well in the field. When bullets are flying and adrenaline is pumping, scrolling through a menu of various modes with a single flashlight button seldom provides the desired outcome. In life-and-death situations, the result can be catastrophic and tragic. Tactical controls are no place to cut costs.

Other flashlights use a selector ring or other switching mechanism to choose the desired mode. While this solution may achieve decoupled operation (separating On/Off from mode selection), such systems are generally not binary and also demand precise adjustment to obtain the desired mode. Additionally, such systems often require two hands to operate (clearly undesirable in a tactical situation).

Proper tactical user interfaces that are both binary and decoupled are exemplified by the unique Tailcaps offered on Elzetta Modular Flashlights. The best-selling Elzetta High/Low Tailcap, as its name implies, provides High and Low output modes. Selection of the mode is achieved by rotation of the Tailcap. If the Tailcap is completely screwed on, High output is engaged; always. Low mode is engaged simply by loosening the Tailcap anywhere from a few degrees to ¼ turn (no precise adjustment is required). On/Off is achieved via the pushbutton, which is the pushbutton’s only function. The system is binary (only High and Low are available) and decoupled (On/Off is completely separate from mode selection). This enables the operator to achieve the desired mode every time, never inadvertently engaging the wrong mode by cycling the On/Off pushbutton. It also allows mode selection to be changed whether the flashlight is On or Off. The simple elegance of this system provides intuitive operation with one hand under high stress.

The Elzetta High/Strobe Tailcap functions identically with a high-frequency Strobe mode replacing the Low mode. The Elzetta Rotary Tailcap takes decoupling even further and separates Momentary-On/Off (activated by the pushbutton) from Constant-On/Off (achieved by fully screwing the Tailcap on). Elzetta Remote Tape Switches work similar to the Rotary Tailcap with a tethered pressure pad replacing the pushbutton.

Selecting an appropriate user interface may be the most importance factor in choosing the best tactical flashlight. What seems nifty in a showroom may prove to be highly detrimental under fire. Understand the importance of a decoupled binary user interface and live to fight another day.