E6B vs AutoNavlog

The app is a computational aid. The E6B is still how you prove you understand the triangle.

Same wind triangle

Ground speed uses the law of cosines: GS² = TAS² + WS² − 2·TAS·WS·cos(wind-from − course). WCA comes from the same triangle. AutoNavlog stores WMM variation East-positive and converts MC/MH the paper way (East is least).

Rounding a CFI will look for

• Time: ceil to the next minute
• TAS: floor to the next knot
• Fuel flow: ceil to the tenth
• Fuel quantity: floor to the gallon
• Temperature: ceil

Those match the ERAU / XC Nav Log Instructions standards. Cumulative ETE and fuel remaining use unrounded internals and only round in the cell.

What you still do by hand

Compass deviation, in-flight ATE/ATA/GS ACT., and any POH note that is not in the C172S tables. Fetching AWC winds does not replace reading the official FD product.

Checkride habit

Pick one cruise leg. Compute WCA, MH, GS, and ETE on the E6B. If AutoNavlog is more than about 1° / 3 kt / 1 min off, stop and find the input error before you print. Bring both the printout and the E6B work to the oral.