INSTRUMENT FLIGHT RULES WORKBOOK
502. THE COMPUTATION SIDE OF THE CR-2 COMPUTER
Before discussing the required procedures for various calculations, one needs to understand this
chapter is designed as a refresher course only. Based on the skills you learned during Aviation
Indoctrination, these problems are simple in comparison. If you require more detailed
information, refer to your AI pubs, CR-2 Instruction Manual, or consult an academic instructor.
Before attempting to solve the following problems, familiarize yourself with the makeup of the
front side of the CR-2 computer. This computer is nothing more than a circular slide rule
designed for aviation.
503. TIME, DISTANCE, SPEED PROBLEMS
You must learn to use the CR computer to rapidly and accurately solve problems associated with
time, distance, and speed.
When working with time, distance, and speed information, by knowing any two of these you can
find the third by using the index. The index represents 60 minutes (on the inner scale); thus, you
could say that the index is used as a basis for what is happening per hour. Match any distance
with the corresponding time (for a portion of your flight) and every other time and distance will
match correctly around the dial.
A time, distance, and speed problem is set up using the following ratio:
rate per hour
Figure 5-1 Time, Distance, and Speed
5-2 CR-2 COMPUTER