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Comment by gus_massa | Hacker News Reader

Just for comparison, look at the standard "landing" sign in an airport https://www.google.com/search?q=airplane+landing+sign&tbm=is... I always chuckle

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Oh cool, now we know why it looks so stupid: it's because it's almost impossible to distinguish takeoff from landing if you don't exaggerate the angle.

Exactly, that's why I think this is a great pictogram: it makes it clear what it's supposed to represent, even though it has nothing to do with what a healthy landing looks like. A pictogram's job is to fit most people's conceptual model of what it represents while being simple and distinguishable, not to be an accurate representation of whatever it stands for.

This pictogram is simple (just a few shapes), it's easy to distinguish (e.g. from the pictogram for "departure"), and it fits most people's conceptual model of a landing (plane comes down from sky to earth).

Now that you point it out, that icon is terrifying

Huh, I have a question about that: do planes actually point downward at any point during a normal descent, or do they just adjust velocity and control surfaces so as to produce less lift?

I understand that planes are pitched upward at the moment of landing, but I don't know if that's true during all stages of normal flight or not!

Generally speaking, during the approach the nose of the plane will actually be pointed slightly downward to control the airspeed (pitch for airspeed, power for altitude). Once you cross the threshold, the pilot generally removes any remaining power and begins to pitch the airplane upward (flare) to reduce the airspeed to stall the airplane. Ideally, the airplane basically stalls at the exact same time the wheels touch down on the runway.

General aviation airplanes typically fly nose-down during final approach, then pitch nose-up for the flare. Jets typically fly slightly nose-up during final approach and maintain the same attitude during the flare (or you could say they don't flare, they just fly straight down to the runway).

They do point slightly downwards during approach, before levelling off then pitching upwards slightly before touchdown.

> do planes actually point downward at any point during a normal descent

For a "Sarajevo Approach" the nose of the plane actually points down until the very last moment [0]. I saw once live and it looked quite sketchy but they routinely did this routinely during the Bosnian war in order to stay out of the range of rockets for as long as possible.

[0] https://www.youtube.com/watch?v=hNQRGOgHrZU and https://www.youtube.com/watch?v=gc6s9fopyg8

Previously known as the "Khe Sanh approach" [0]

[0] http://h2g2.com/approved_entry/A4187621

From your link:

>One of the weirdest things about this is the fact that you get to see the upper side of the wing. With planes this big, this rarely happens. If you see them on the ground, you walk under and around them, always looking upwards. When you see them in flight, you obviously very rarely get to see them from any quarter other than below. Seeing the top half of the Hercules like this therefore feels inherently wrong, especially since the plane is pointing directly at the ground. Like seeing a picture of sinking ship perpendicular in the water or a crashed car upside-down with wheels still gently turning, seeing the unfamiliar upper side of the wing induces a sort of subconscious panic.

This perfectly explains what I was feeling when I was watching GP's youtube links.

Just as an aside: if you have too much energy on approach in a small single engine piston plane (e.g. a Cessna 172), you can pull the throttle to idle, pull the nose up until you're below full flap extension speed (85 knots), then put in full flaps, and then point the nose down and keep descending (in a steep nose down attitude) at 85 knots. It's quite fun, and brings you down fast (i.e. steeply).

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