Monday, February 5, 2018

Retro Review: ASA CX-1 Pathfinder

Retro Review:  ASA CX-1 Pathfinder

Quick Facts

Company:  ASA (Aviation Supplies & Academics, Inc., )
Type:  Aviation, Flight Calculator
Original Cost:  unknown, but ASA’s current version, the CX-3 sells for $99.95, my guess would the CX-1 originally sold for that amount
Year that the CX-1 was produced:  The late 1980s
Batters for the CX-1:  2 CR 2032 batteries (the CX-3 has 4 AAA batteries)

How I Acquired the CX-1

I picked up the CX-1 at a yard sale for $1.  It needed new batteries, thankfully the battery compartment was still good.  Replacing the batteries on the CX-1 required me to remove two plates on the back.  Thank goodness for the small screwdriver sets.


The CX-1 (and subsequently the CX-2 and CX-3) is a unique type of calculator, which focuses on solving problems in aviation, as well as a timer, stopwatch, work with time (hours-minutes-seconds), and conversions.  The keys are soft, so presses have to be deliberate.

Solvers:  Aviation

The CX-1 had a vertical screen separated into two parts:  the above portion has the calculator and the solver and its prompts.  The CX-1 is an LCD calculator, hence the prompts for the solver were locked in place.  When using one of the flight applications, whatever prompt you are working with flashes. 

The bottom part of the screen contained all the solvers available.  I wasn’t able to find a manual for the CX-1 online but was able to find one for the CX-2 and together with the help card that came with the calculator to determine which solvers were included. 

Units used:

Temperature:  Celsius (°C)
Speed: Knots
Distance: Nautical Miles (usually)
Volume:  Gallons

Row 1 (from top to bottom):
Plan CAS
Calculate true air speed (TAS) given outside temperature and calibrated speed (CAS)
Calculate TAS given total temperature and CAS
Plan M#
Calculate TAS given outside temperature and mach #
Act M#
Calculate TAS given total temperature and mach #
Calculate TAS and heading (direction) given wind and course speed conditions

Row 2:
Calculate true heading given TAS, course, wind conditions
Calculates head wind (head wind is negative (in your face), tail wind is positive (wind at your back)), and X-Wind (left wind is negative, right wind is positive)
Unknown wind: calculates wind speed and direction given course direction and speed, TAS, and flight direction
Calculate GS given wind conditions and TAS
Calculate heading TAS given wind conditions and GS

Row 3:
Leg Time
Calculate time duration of a leg given distance and GS
Fuel Burn
Calculate the amount of fuel consumed give fuel burn rate and time
Calculate fuel rate (burned per hour)
Calculate how long a flight can endure given fuel capacity and burn rate
Dst Fln
Calculate distance flown given time and fuel burn rate

Row 4:
Weight – arms of an airplane (?)
Mean Aerodynamic Chord calculation
Weight - Momentum

Note CAS does not mean computer algebra system for the CX series.

In regards to direction, direction is measured in degree angles 0° to 360°, with respect to due north (I think), meaning at 90° wind goes west, 180° wind goes south, and 270° goes east.

Navigating the solvers takes a little bit getting used to, which is controlled by the arrow keys ( [ ← ], [ → ]).  The left key also acts as down when you are at the first item in a row, while the right key also acts as up when you at the last time in a row.  The solver that is being selected will have its prompt flashing.

Entering Hours-Minutes-Seconds

Use the [ T ] key after each component.  For example to enter 23 minutes 28 seconds, press 0 [ T ], 23 [ T ], 28 [ T ].

Timer and Stopwatch

To activate the stopwatch, press the [TIMER] key.  To stop the stop, press the [TIMER] again.  Clear the stopwatch by pressing the [ C ] key.

For the timer, enter a time and press [CONV] [TIMER].  The CX-1 does not have a beep.


The CX-1 features a handful of conversions, all accessed by pressing the [CONV] key first. 

Conversions available:

* Hours/Hours-Minutes-Seconds (HMS)
* Gallons/Liters
* Feet/Meters
* °F/°C
* Kilograms/Pounds
* Statue (regular) Miles (SM)/Nautical Miles (NM)
* Kilometers/Nautical Miles (NM)

The Updated CX-3

The current version, the CX-3 has a backlit, color screen, and can be flash updated.  Added in the second version are density altitude and rhumb-line navigation calculations.  Also the weight calculations have been streamlined.  I think the square root function is also added. 

Final Verdict

For a specialized calculator in aviation, the CX calculators (seemingly) fits the bill.  The keys on the CX-1 are soft, but are easy to use.  To the key is to pay attention to the prompts.  The CX series either enhances or replace the flight computer slide rules.  If you are into aviation or a profession, the CX is worth checking out.


This blog is property of Edward Shore, 2018

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