ASA CX-3 Computer: Simple, Full Featured

ASA updates the CX-series E6-B electronic flight computer with a color display, faster processor and slimmer footprint.

At a time when nearly every pilot struts around with a tablet computer or smartphone running their favorite navigation app, we were surprised to see that pilot supplier giant ASA (Aviation Supplies and Academics) redesigned its CX-series flight computer.

Still, more than one high-volume mail order house, including Sporty’s, told us the new ASA CX-3 computer is in strong demand. There’s a reason for that. You can’t take any FAA knowledge exam with any type of tablet or smartphone. But the dumbed-down ASA CX-3 is fair game, since it’s authorized for use on FAA (and Canadian) exams.

Curious as to how dumbed down the ultra-modern new CX-3 really is, we ordered one to see if it’s worth the $79.95 asking price. Here’s a field report.


If you haven’t taken an FAA knowledge exam lately, FAA Order 8080.6 and Advisory Circular (AC) 60-11 cover test aids and materials that may be used by airman knowledge testing applicants for all pilot, mechanic, dispatcher and other FAA exams. The CX-3 is fully compliant.

The redesigned CX-3 is the follow-on product to the ASA CX-2. At roughly 3 inches wide, 6.5 inches high and 3/4 inches deep, the .70-pound CX-3 feels like a big smartphone. Remove the plastic protective cover and it looks like a traditional handheld calculator.

The device is styled for stashing in a map pocket or flight bag, but we think the casing is too slick. It has a thin non-slip strip on the back to keep it from sliding on a surface, but it came out of the hand in turbulence. Battery endurance is impressive on four AAA alkalines. Plan on 20 hours of continuous use when the device is set for full brightness.

We like that you can choose between four backlighting options, depending on the ambient light in the cockpit. In normal mode, the screen is backlit and the function keys aren’t, while in daylight mode, the screen is always at full brightness (and the characters are black)—which works we’ll in sun-splashed cabins. In the night mode, the screen has a black background (with green and white characters) and the keypad is lit. There’s even a dusk mode—which turns down the display backlighting to medium-low.

ASA did a good job of keeping the CX-3’s menu structure shallow and it’s nearly impossible to get lost in any menu. Think in terms of input and output. Any CX-3 function can be reached with a maximum of two keystrokes, and you can go directly to the Flight, Plan, Timer, Calculator and Weight and Balance menus with dedicated function keys for each operation.

To help ease the data entry process on the fly, the single-line inputs and outputs of each function are clearly separated on the display to distinguish between entered numbers and calculated values, along with their corresponding units of measurement. ASA says the computer’s menu organization reflects the normal process for planning and executing a flight, which is true. The result is a natural flow from one function to the next with a minimum of keystrokes. Logically, when planning a flight, simply work from the menus in sequential order as you fill in your flight plan

form. The computer prompts you for the input with an amber question mark, and the answers will display with a green equals sign.

Better yet, you can perform chain calculations where the answer to a preceding problem is automatically entered in subsequent problems. This saves the tedious effort of entering data more than once. And, standard mathematical calculations and conversions can be performed within each aviation function without having to back out of menus to get the calculator functions.

The CX-3 is smart enough to remember previously entered aircraft profile data (it remembers the most recent display of variables, whether it was an input or an answer) thanks to its non-volatile memory storage. This means stuff you use the most—like weight and balance base figures and trip planning constants—are stored in the computer until you perform a memory reset or remove the batteries. For software updates, the device has a Mini-B data port on top of the case.

Speaking of weight and balance, we like the Weight Shift Formula function. This computes the amount of weight that must shift to move the CG to a desired location in the airframe.

For large aircraft, there is the %MAC function, which expresses the CG as a percent of the mean aerodynamic chord.

FAT aviation BRAIN

We can’t come close to covering all of the CX-3’s functions, but we’ll touch on some that stand out—both basic and advanced.

As rudimentary as it may sound, some of the more useful features in the CX-3 are its timers and clocks. There are two timers, including a stopwatch and a countdown timer that you might use for switching fuel tanks or timing an approach segment. Heck, we think the timer and clock utilities are better than the ones on a Garmin D2 aviator watch. An internal clock runs even when the unit is powered off, and it can display local time, destination time and UTC.

As you would expect, the CX-3 is all about computing complex conversions, and there are 12 categories in all to include distance, speed, duration, temperature, pressure, volume, rate, weight, rate of climb/descent, angle of climb/descent, torque and angle. These 12 conversion categories contain 38 different conversion units for more than 100 functions.

With the FLT mode (E6-B functions) it’s easy to see why the CX-3 could be as useful in a knowledge exam as it is in the cockpit. The dedicated Conv Unit key is used to quickly convert items like gallons to pounds, knots to MPH and Celsius to Fahrenheit temperature. The FLT function handles pressure altitude and density altitude calculations.

As one example, say you plan to fly at 4500 feet indicated altitude and the current altimeter setting is 30.15. To figure out which pressure altitude you should use to calculate the true airspeed, press the FLT key, highlight the Altitude line and enter 4500. Then enter the 30.15 for the altimeter setting. The computer will spit out 4289 feet as the pressure altitude.

Need a fast density altitude conversion for an airport where you know the field elevation? Enter the indicated altitude, enter the baro setting and then enter the outside air temperature. The computer does the rest, displaying the pressure altitude and density altitude.

There’s also a cloud base function, which computes the altitude of the cloud base after you key in the dew point and OAT at the airfield. For example, if you enter the surface temperature as 90 degrees and the dew point as 45 degrees, the CX-3 does the math, putting the clouds at 10,227 feet AGL.

Perhaps a favorite tool (also in the E6-B group) is the Holding Pattern utility. With limited data entry, it prompts with the recommended holding pattern entry. Say you’re instructed to hold on a 270-degree radial while flying on a 160-degree heading. In the FLT menu, select Holding Pattern. Key in 160 for the heading and 270 for the holding radial. The display would show “Direct” as the entry procedure and 90 degrees as the inbound heading to fly.

On a side note, you can also source holding pattern guidance from a Garmin or Avidyne GPS navigator. In Garmin’s GTN750, you can add a hold to any flight plan waypoint, specifying inbound or outbound course, direction of turns and time or distance legs. The navigator shows the entry on the moving map for when you cross the holding fix. The utility also exists in Garmin’s G1000. For use in some flight simulators and real airplanes not so equipped, the CX-3’s holding pattern is a useful tool.

If you’re not up for figuring out wind correction angles on a traditional E6-B (see the sidebar above), the CX-3 has plenty of capability. The Wind Component utility computes the headwind or tailwind component, plus the crosswind component for a given wind and runway. But you have to enter the data correctly—something we botched at first, followed by some head scratching.

Since the required data inputs are wind speed, wind direction and runway, you enter the runway number and not the runway’s magnetic course. For example, type 24—not 240—for runway 24. For a crosswind component from the left, the computer displays a negative value. From the right, it’s a positive value.

BELT, SUSPENDERs AND A learning tool

Not every pilot needs the CX-3 computer, but we think plenty can benefit from its utility. Plus, the price is right. On the other hand, like you, we’re we’ll aware of the flight planning and E6-B functions that are built into popular navigation apps and even within the auxiliary menus of GPS navigators.

We’ll look at those capabilities and see how different programs are equipped in an upcoming series on tablet navigation apps.

ASA’s Brian Snider understands the reality of the modern competition, but makes a good point when it comes to the device’s utility as a learning tool.

“Using an electronic flight computer like the CX-3 helps students understand the relationship between the components and variables involved in an equation, the data that is needed to complete the equation and how to more accurately pinpoint the answer for a given test question or real-world situation,” he said.

Of course, we think there is value in having all of that computing power in a standalone, separate device. The CX-3 doesn’t rely on a Wi-Fi connection, isn’t affected by program crashes and serves as a belt-and-suspender standby tool.

ASA covers the device with a five-year limited warranty, provides a protecting storage cover and a set of batteries and it is available from ASA directly, or from a variety of retailers.


Long before electronic flight computers, tablet apps and GPS navigators made child’s play out of on-the-fly aviation math, there was the E6-B, affectionately nicknamed the whiz wheel. There’s some interesting history behind the device, and for aviation buffs it’s worth a Google search. Developed in the 1930s by naval Lt. Philip Dalton, the E6-B name carries over from the original part number for the U.S. Army Air Corps. Over 400,000 E6-B’s were manufactured during World War II and most were made of plastic that glowed under black light-illuminated fighter cockpits. My use of the whiz wheel is far less glamorous, but I remember demonstrating my proficiency with it during a checkride in a Cessna 150 in the mid-1980s. The same well-worn whiz wheel has a spot for life at the bottom of the flight bag.

If you’ve never used a whiz wheel, it has two main parts: a circular slide rule side for making quick airspeed and density altitude calculations (to name two), plus a wind side for computing groundspeed and wind correction angle. The slide portion of the circular slide rule is packed with quick-reference data, including crosswind correction, or the angle between the wind direction and true course. You can also solve problems involving fuel consumption, fuel endurance and fuel capacity, plus time-speed-distance.

ASA currently sells no fewer than five different models of its AirClassics mechanical flight computer. The $34.95 flagship ASA-E6-B is a color version shown in the main photo below. It’s the same whiz wheel ASA has sold for years, but enhanced with color markings for easier readability. Made of brushed aluminum, the wheel and slide-equipped computer measures just shy of 10 inches long and 5 inches wide. If that’s too big to carry around (it comes with a storage pocket), the $29.95 Micro-E6-B is 6 inches long and 3.5 inches wide. It has a high- and low-speed wind correction slide, plus all of the other functions found on the larger computer. There’s also the $12.95 paper model, which is made from solid heavyweight fiberboard.

ASA also sells the $12.95 model E6-B High Speed Slide. This is a companion product for high-speed flight (220 to 700 knots) computations. It has a compressibility correction chart, worldwide time correction chart and an ICAO Standard Atmosphere reference table.

After using ASA’s CX-3, it would be tough to go back to an old-school whiz wheel, but it’s a money saver and more interesting than typing in the data.

Editor in Chief Larry Anglisano has been a staple at Aviation Consumer since 1995. An active land, sea and glider pilot, Larry has over 30 years’ experience as an avionics repairman and flight test pilot. He’s the editorial director overseeing sister publications Aviation Safety magazine, IFR magazine and is a regular contributor to KITPLANES magazine with his Avionics Bootcamp column.