Great question to start with!

As an airline pilot, one of the first things you learn in flight planning is that the Earth is a globe, not just because it’s what textbooks say, but because you see and fly it every day. Pilots don’t just rely on visual confirmation from high altitudes (though yes, you can see the curvature from a cruising altitude of 35,000 feet on a clear day); we also have to understand the shape of the Earth to fly efficiently.

Let me explain:

🌍 We fly Orthodromic Routes (great circles) When planning long-haul flights, we don’t fly in a straight line on a flat map. We use what’s called the orthodromic route, or great circle route, the shortest path between two points on a sphere. On a 2D map, this looks curved, but in 3D space, it’s actually the shortest distance.

That’s why a flight from New York to Tokyo, for example, curves up over the Arctic instead of going straight west. If the Earth were flat, the shortest path would be a straight line across the Pacific, but that’s not how it works.

🧭 Loxodromic Routes are for simplicity, not efficiency Sometimes, especially in older navigation systems or short-distance flights, we might use a loxodromic (rhumb line) route: one that maintains a constant compass bearing. On a flat map, it looks straight, but on a globe, it's longer and spirals toward the poles. It's easier to follow but less fuel-efficient.

The fact that we even distinguish between these two types of navigation proves we’re dealing with a curved surface, not a flat one.

✈️ High Altitude Views Seal the Deal From 35,000 feet, with good visibility, you can see the horizon gently curve, especially over oceans or polar regions. It's subtle, but real. And the higher you go (like in a business jet or Concorde), the more obvious it becomes.

So from my experience, I'd say that the Earth isn’t flat. If it were, our navigation systems, flight routes, fuel calculations, and even satellite communications wouldn’t work the way they do.