Technique - Computing time, fuel, distance
Technique - Computing time, fuel, distance
When it comes to planning cross-countries, "I always use my calculator and my electronic E6B. And besides, there are so many websites that calculate this stuff for me!" That may be the case, but for the practical test, you may have to go back to the basics. The E6B is a surprisingly effective way to master simple time/speed/distance/fuel burn problems. Make friends with your E6B and see how much fun it is.
1. Distance
Plot a course between two airports or two checkpoints. The ASA E6B we used for this exercise can be used as a plotter; it displays statute and nautical miles for world aeronautical charts and sectional charts on its sides. We chose a leg between Frederick Municipal Airport (FDK) and Smoketown Airport (S37); the distance is a straight-line 66 nm.
2. Time
Now let’s find the time en route. We are flying a Cessna 172 with a groundspeed we determined is 130 knots. We first line up the E6B’s rate arrow to 130 (13) on the outer ring. We then look on the outer ring to find 66 nm. Directly opposite that is the time en route—30 minutes and 30 seconds.
3. Fuel
How far can we go if we want to fly past Smoketown? Assume the fuel on board has an endurance of 4.5 hours, and we know our groundspeed is 130 knots. Set the rate arrow at 130 on the outer scale. Now look for 4 hours and 30 minutes (4:30) on the inner scale. Directly opposite that is our range (endurancetime)—585 nm.
How much fuel will we burn on our FDK-S37 leg? Looking in the pilot's operating handbook for a Cessna 172, we determine a fuel burn of 7.5 gph for a given power setting. Set the rate arrow to 7.5 gallons on the outer ring. Now look for 30 minutes, 30 seconds on the middle ring. Our fuel burn—just about 3.75 gallons—is shown opposite, on the outer ring.
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