Everything a student pilot needs to actually use the manual E6B (whiz wheel) on a checkride — wind side, calculator side, and the seven problems an examiner will ask you to solve.
Designed
1933 by Lt. Philip Dalton, USN
Typical cost
$30 manual / $90 electronic
Core calculations
7 (TSD, fuel, TAS, DA, WCA, crosswind, conversions)
Required for
Private, Instrument, Commercial checkrides
Time to fluency
~10 hours of focused practice
The E6B flight computer — affectionately called the "whiz wheel" — is a circular slide rule designed in the 1930s by U.S. Navy Lieutenant Philip Dalton. Nearly a century later it's still standard equipment on Private, Instrument, and Commercial checkrides. Examiners ask for it because it proves you understand the relationships between airspeed, temperature, wind, fuel, and time — not just how to tap a button on ForeFlight.
This guide walks through every calculation you'll be asked to perform, with the exact knob-turning sequence for each. If you can do these seven problems cold, you'll never sweat the cross-country planning portion of an oral exam again.
What the E6B Actually Is
The E6B has two sides:
Calculator side (front): A circular slide rule with an outer scale (usually labeled in minutes/distance/fuel) and an inner scale (time in hours). Anything that's a ratio — speed, fuel burn, unit conversion, density altitude — happens here.
Wind side (back): A rotating azimuth disk over a sliding grid. This solves the wind triangle: given wind direction/speed, true course, and true airspeed, find your wind correction angle and groundspeed.
A standard aluminum E6B (the ASA CX-2's mechanical cousin or the classic Jeppesen CSG-1) costs about $30. It will outlast every iPad you ever own and never goes dark over the Sierras.
The Seven Problems You Must Be Able to Solve
1. Time, Speed, and Distance
The foundational E6B skill. Place the rate arrow (60) on the inner scale under your groundspeed on the outer scale. Now any distance on the outer scale lines up with its time on the inner scale.
Usable fuel 38 gal at 9.2 GPH → endurance = 4 hours 8 minutes
Always add your reserve after the calculation — day VFR requires 30 minutes at cruise per FAR 91.151, night VFR 45 minutes.
3. True Airspeed (TAS) from Indicated Airspeed
Use the small window on the calculator side.
Frequently Asked Questions
Q1Do I need a manual E6B if I have an iPad?
Yes. Most DPEs allow electronic flight bags during the checkride, but they frequently ask you to demonstrate at least one calculation — typically wind correction angle or density altitude — on a manual E6B to confirm you understand the underlying math. A manual aluminum E6B costs about $30 and is required equipment at most Part 141 schools. It's also your backup when an iPad overheats or dies in cruise.
Q2What does E6B stand for?
E6B is a U.S. Navy designation, not an acronym. The "E" indicates electronics/computing equipment, and "6B" was the model number assigned to Philip Dalton's circular flight computer when the Navy adopted it in the late 1930s. The design itself dates to a 1933 patent. It has been refined repeatedly but the core slide-rule mechanic — and the name — has been unchanged for nearly 90 years.
Q3How do I find true airspeed on an E6B?
On the calculator side, locate the small window labeled "For Airspeed and Density Altitude Computations." Align your pressure altitude with the outside air temperature in Celsius. Without moving the wheel, find your calibrated airspeed on the inner scale and read true airspeed directly above on the outer scale. As a sanity check, TAS increases roughly 2% per 1,000 feet of density altitude — so 110 KCAS at 8,000 ft DA is about 125 KTAS.
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"For Airspeed and Density Altitude Computations"
Align pressure altitude (in the window's altitude scale) with outside air temperature (°C).
Don't move the wheel.
Find your calibrated airspeed (CAS) on the inner scale — read TAS directly above on the outer scale.
Rule of thumb to sanity-check: TAS increases roughly 2% per 1,000 ft of density altitude. At 8,000 ft on a standard day, 110 KCAS ≈ 125 KTAS.
4. Density Altitude
Same window as TAS. After aligning pressure altitude with OAT, look at the small density altitude window — it reads directly.
Pressure altitude 5,000 ft, OAT +30 °C → density altitude ≈ 8,000 ft
This is the number that matters for takeoff performance, not your altimeter.
5. Wind Correction Angle and Groundspeed (Wind Side)
This is the calculation most students fumble. The sequence:
Rotate the azimuth disk so wind direction is at the top index (TRUE).
From the grommet (center hole), mark wind speed straight up with a pencil dot.
Rotate the disk so true course is at the top index.
Slide the grid until the wind dot sits on the TAS arc (e.g., the 120 line if TAS is 120 kt).
Read groundspeed under the grommet.
Read wind correction angle as the left/right deflection of the wind dot from the centerline.
Add or subtract WCA from true course to get true heading. Then apply magnetic variation, then deviation, to get the compass heading you'll fly.
6. Crosswind and Headwind Components
Use the wind side or the dedicated crosswind grid printed on most E6Bs.
Mental shortcut: at 30° the crosswind component is half the wind speed; at 60° it's the full wind speed.
7. Unit Conversions
The outer scale has tick marks for NM ↔ SM ↔ km, gal ↔ liters, lbs ↔ kg, and °F ↔ °C. Line the source unit up with its index arrow and read the converted unit on the same scale.
Manual E6B vs. Electronic E6B vs. App
Tool
Cost
Allowed on Checkride
Best For
Manual E6B (whiz wheel)
~$30
Yes, all
Learning the relationships, oral exam credibility
Electronic E6B (ASA CX-3, Sporty's)
~$90
Yes, all
Faster cross-country planning, weight & balance
iPad app (ForeFlight, etc.)
Subscription
Usually yes — examiner's discretion
Real-world flying; many DPEs still want to see the manual unit
Most DPEs will let you use whatever tool you brought, but they'll often ask you to demonstrate one calculation on the manual E6B to prove you understand the math. Don't show up without one.
When You'll Actually Need It After the Checkride
Honest answer: rarely, in the cockpit. Modern EFBs handle the wind triangle in real time using GPS groundspeed. But the underlying skill matters because:
iPad batteries die. The E6B is your backup.
Cross-country planning required by FAR 91.103 (preflight action) means computing fuel and time before you launch — the E6B is faster than you'd think once you're fluent.
Density altitude awareness at high-elevation airports is a survival skill. Knowing that 5,000 ft of pressure altitude on a 95 °F day means an 8,500 ft DA could keep you out of an NTSB report.
Aeronautical knowledge standards under FAR 61.105 explicitly include navigation and flight planning by reference to manual computations.
ACS Standards You're Being Tested Against
The Private Pilot ACS Area of Operation I, Task D (Cross-Country Flight Planning) requires you to:
Compute headings, flight time, and fuel requirements
Apply pertinent information from charts, the AIM, and weather reports
Recompute fuel reserves based on changing conditions
Commercial and Instrument ACS add wind correction at altitude and IFR fuel reserves under FAR 91.167 (45-minute alternate fuel). The E6B is the tool that produces these numbers in your nav log.
Common Mistakes That Cost Students Points
Confusing pressure altitude with indicated altitude. Set the altimeter to 29.92 to read pressure altitude — or compute it: PA = field elevation + (29.92 − local altimeter) × 1,000.
Using °F instead of °C. The E6B is calibrated in Celsius. Convert first.
Forgetting magnetic variation. Wind side gives you true heading. You still owe the examiner true → magnetic → compass.
Putting the wind dot below the grommet instead of above. The dot represents where the wind is coming from; with the wind direction at the index, it goes up.
Sliding the grid the wrong direction so the dot lands off-scale. If your TAS is 120 and your dot is way past 200, you flipped a step — start over.
How GroundScholar helps with this
E6B problems are pattern recognition: once you've solved fifty, the fifty-first takes thirty seconds. GroundScholar's adaptive drill engine generates fresh wind-triangle, fuel, and density-altitude scenarios at exactly your difficulty level, then explains the manual E6B sequence step-by-step when you miss one. No two practice sets are the same.
In our mock checkride, the AI examiner will hand you a cross-country leg with realistic winds aloft and a non-standard temperature, then probe your reasoning the way a real DPE does: "Walk me through how you got that wind correction angle. What changes if the temperature drops 15 degrees?" Every answer is graded against the current ACS, and every regulatory cite is verified against the live FAR/AIM.
You won't memorize an E6B from a YouTube video. You'll learn it by solving problems under pressure until the knob-turning is automatic.
Q4How do I calculate wind correction angle on the E6B?
Rotate the azimuth disk to put wind direction at the top index. From the grommet, mark wind speed straight up with a pencil. Rotate the disk to put true course at the top index. Slide the grid until the wind dot sits on the arc matching your TAS. Read groundspeed under the grommet, and read wind correction angle as the left or right deflection of the wind dot from the centerline. Apply WCA to true course to get true heading.
Q5Is the electronic E6B easier than the manual one?
Faster, yes. Easier to learn, no. Electronic units like the ASA CX-3 require you to navigate menus and remember which screen handles which calculation. The manual E6B is one-screen-always-visible and forces you to understand the relationship between variables. Most instructors recommend learning the manual E6B first, then optionally adding an electronic unit for cross-country planning speed. The manual unit is sufficient for every checkride task.
Q6What's the difference between density altitude and pressure altitude?
Pressure altitude is your altitude above the standard datum plane (29.92 inches Hg) — set your altimeter to 29.92 to read it directly. Density altitude is pressure altitude corrected for non-standard temperature: it tells you what altitude the airplane *thinks* it's at for performance purposes. On a hot day, density altitude is significantly higher than pressure altitude, which means longer takeoff rolls, reduced climb rate, and degraded engine performance. The E6B computes DA in the airspeed window.
Q7Can I use a regular calculator instead of an E6B?
For time-speed-distance and fuel burn, yes — a basic calculator works fine if you know the formulas. But the E6B's wind side solves the wind triangle graphically without trigonometry, which is faster than computing sines and cosines by hand. Most DPEs expect to see either a manual or electronic E6B during cross-country planning. Showing up with only a calculator will work, but it signals weak preparation.
Q8How long does it take to get fluent on an E6B?
Most students need about 8-12 hours of focused practice across two to three weeks to be checkride-ready. The first hour is figuring out which way to turn the disk; hours two through five build muscle memory on the seven core problems; the remaining time is speed under pressure. Fluency means solving a wind correction problem in under 60 seconds and a fuel/time problem in under 20. Daily 15-minute drill sessions beat weekend cram attempts.
E6B Flight Computer: How to Use the Whiz Wheel | GroundScholar