Notes from Airplane Chief Instructor - Peter Swift  With the proliferation and popularity of GPS, do we really need the E6B? What value does this most venerable instrument serve? After all most aircraft nowadays come with a GPS built in and IPads and smart phones all have the ability to have aviation software tied into their on board GPS as well as the many hand held GPS systems out there already configured for aviation. So...here are a few things to consider and ways in which the E6B and GPS are actually complimentary to each other. 1) The E6B is "fail safe"...no batteries, no power requirements at all, can be dropped, stepped on, soaked in water, frozen, etc etc and still keeps on working...! 2) No pages to scroll through, cursor key to press, sequence of button pushes to remember or screens that pop up seemingly from nowhere that only encourages the pilot to utter some rather colorful language...! 3) The GPS will inform you of the time and distance to a way point programmed in to it...But the E6B will inform you at a glance of the flight time to ANY point... Just follow these steps: a. Read the ground speed off the GPS b. Rotate the dial on the E6B until the Speed Pointer (the black triangle pointer) is aligned with the ground speed. c. Pick any number on the outer dial (this is distance) and aligned with it on the inner dial is the time it will take to go this distance.
Using this simple technique will enable you to quickly decide if a course deviation is possible (do I have enough fuel...) while still leaving your primary destination up on the GPS.
Along with this there are some simple estimation techniques that will give you information for decision making without having to "upset" your already carefully programmed GPS
To compute distances to a location on your chart do the following:
1) Use the GPS to inform you where you are now and locate this on the chart.
2) Bend your thumb at a right angle and place the joint at this point.
3) The distance from the joint to the tip of your thumb is about 10 nautical miles on a sectional chart. It is 5 nautical miles on a Terminal Area chart.
4) Keep moving your thumb "joint to tip" and adding in your head as you go until you reach the destination. You now have the total distance and one glance at your E6B will give you the time to get there.
One other "rule of thumb" that is very effective to get an estimate of your TAS (true airspeed) is as follows:
1) Read your altimeter and multiply by 2 the first 2 digits. As an example if the altimeter shows 6,000 ft., multiply 6.0 x 2 = 12. If the altimeter shows 7,500 ft, multiply 7.5 x 2 = 15
2) Add this number to your IAS (Indicated Airspeed) to approximate your TAS.
Use of this technique will enable you to have in your head your approximate TAS so when you use the E6B or GPS to compute actual TAS you can verify that you entered the date correctly.
Blue Skies,
Peter Swift, Chief Instructor
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