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Comment by tropo | Hacker News Reader

I don't think you need to "go from wings level to a banked turn at exactly the right moment" for this. There are two ways to make it work.

As proposed, the runway is banked. You bank your aircraft well above the runway surface. You fly above the runway, possibly following it as your holding pattern prior to landing. You can keep going around, banked already. When it is your time to land, you continue around in that bank and descend to the runway.

Alternately, it could be unbanked with straight landings. This makes the circle considerably thicker. Landing is quite normal, aside from the runway markings.

BTW, your "kick out of the crab angle just prior to touchdown" method may be standard, but it is pretty bad. The B-52 gets this right, with 4 pairs of wheels that touch the ground at the same time and are all capable of being rotated.

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The whole point of a stabilized approach is to avoid unnecessary maneuvers in the final moments of flight, and to simplify decision making. Your approach is a straight in powered glide. If you like where you end up, you cut power, flare and land. If you don't like the situation, you apply full power and climb straight ahead, then turn according to the rejected landing procedure for the runway or ATC instructions.

What you describe needlessly adds complication to the approach, which adds risk, which will certainly result in accidents and fatalities. It's just a bad idea, and there is a reason airport designers never considered this (it is not as if the idea of banked curved roadways is new).

Sorry as a pilot, I can say this is not just a bad idea, it is a lethally bad idea. A fun simulator challenge, but not something that will work in the real world. If you are doubtful, I would suggest you try circling around a point in IFR conditions within 50' lateral tolerance above a circular runway. Be sure to add zero visibility and a 10-20 knot cross wind to simulate doing so in the clouds above the runway as you descend.

> Be sure to add zero visibility and a 10-20 knot cross wind to simulate doing so in the clouds above the runway as you descend.

With a circular approach to a circular runway, aren't all winds cross winds (and, also, headwinds and tailwinds)?

That was a trick suggestion. Also while dealing with flying the airplane, also be sure to keep track of whether the landing pattern is clockwise, or counter-clockwise, or was it clockwise, and which heading you are currently on and how that relates to your rejected landing turn in case you need it, which you probably will. I don't see what could possibly go wrong.

All I'll say is if I was the head of the programming committee for the air transport association conference, I would invite the designer to keynote, as comic relief.

I don't see why a human has to do this.

Even if they do, I don't see why it can't be done with an awareness system like the F-35 helmet. That would let you see the outline of the runway through arbitrary fog.

There is no special "rejected landing turn". You rise up just a bit, keep following the runway, and retry when you wish.

> I don't see why a human has to do this.

Because automated systems fail.

> Even if they do, I don't see why it can't be done with an awareness system like the F-35 helmet.

Because most aircraft aren't F-35s and expenses and fallible systems that are appropriate and sensible for combat aircraft that may have to operate in conditions in which civilian aviation would not aren't necessarily something you want to make civilian aviation dependent on in conditions in which, with sensible things like straight runways, it would not be.

> I don't see why a human has to do this.

Because a human driving the plane has a vested interest in surviving the landing.

A person who writes buggy landing software, or an operator "piloting" it from the ground can get another job if they fail.

The Romans would put civil engineers underneath newly-built bridges, then march the army over. Very few low-quality bridges were built, and nobody built more than one low-quality bridge.

This sort of thing works for planes too.

No. Wind can be circular. For example, right above the runway could be the eyewall of a hurricane.

Good point.

That might produce other problems for landing, though.

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