FE Meme
Flight Dynamics Assumes Flat Earth
#211: A flight-dynamics summary assumes a flat, non-rotating Earth, circled as proof pilots use flat-Earth math.
The Meme
Textbook page "Flight Dynamics Summary" with red oval highlighting bullets: flat Earth and non-rotating Earth assumptions.
Why It Spreads
A textbook Flight Dynamics Summary page with flat Earth and non-rotating Earth bullets circled in red feels like an official aerospace leak. Screenshot culture treats any syllabus phrase containing flat Earth as cosmology proof, especially when it appears inside real engineering coursework.
What It Gets Wrong
The red oval on a textbook "Flight Dynamics Summary" page highlighting flat, non-rotating Earth assumptions treats a local tangent-plane simplification as a cosmology confession. Over short range on R ≈ 6371 km, surface drop ≈ d²/(2R) is only ~8 m over 20 km, so engineers use local-level frames with explicit error bounds, then switch to WGS84 geodesics and Coriolis terms for long-range INS and FMS planning. Great-circle polar tracks on ellipsoid charts are not hidden by assumption lists that name when simplifications break down. TestTheGlobe's Aircraft Never Dip The Nose and TestTheGlobe's Flight Paths walk through the observations and predictions this image skips.
The Debunk
The red oval on a textbook "Flight Dynamics Summary" page highlighting flat, non-rotating Earth assumptions treats a local tangent-plane approximation as a cosmology confession. Over short range, Earth's ~6371 km radius makes surface curvature negligible: drop ≈ d²/(2R) is only ~8 m over 20 km, so local-level frames are standard engineering simplifications.
- Tangent-plane models hold over limited distance without endorsing flat-Earth cosmology; TestTheGlobe's Aircraft Local Level shows when local-level assumptions apply and when global geodesics take over.
- Long-range planning uses great circles on the WGS84 ellipsoid; TestTheGlobe's Flight Paths plots routes that exceed the textbook's short-range flat patch.
- Aircraft trim to local level, not constant nose-down pitching at ~15°/h; TestTheGlobe's Aircraft Never Dip The Nose explains why pilots do not chase curvature degree by degree.
- Curved routes on flat wall maps are projection artifacts; TestTheGlobe's Flights Only Make Sense On A Flat Map addresses the related misread of airline paths.