[pilot7378535]

"Flying cars" made sense to me until I started flying. Now I think "driving airplanes" is the more appropriate phrase for what might be in the realm of possibility.

For example: here's how you'd prepare to visit distant relatives with each vehicle:

Car: load up however much weight you want, turn the keys and start driving. Low on gas? Just turn off at the next exit. Weather looks bad? Just drive slowly and carefully and you'll be fine.

Airplane: visually inspect your vehicle, be careful distributing limited weight around the cabin, get a weather briefing and accept that many days you just can't fly, break out your slide rule (literally!) and plot a course between waypoints, with calculations accounting for wind deflection, magnetic variation, fuel burn, and various other factors. And don't forget to plan out refueling stops and emergency airfields too. Then run through your checklist and (once you get permission from the tower, if any) take off.

I never appreciated how user-friendly modern cars are until flying. And air travelers are spoiled by all-weather jetliners piloted by the pros.

[Johnny555]

Couldn't most of that be done by computer? Weight sensors in the wheels can determine weight and balance, the computer can evaluate the weather and plot the course taking into account all of the factors you noted, including refueling stops and emergency airfields, and it can even run through the checklist for you.

About the only part of that it can't do is the visual inspection.

[pilot7378535]

Sure, if you trust the correctness of the computer's software with your life and the lives of any passengers. There are popular apps now that do some of what you suggest, especially trip planning.

I've seen enough bugs in my day job to want to at least verify the computer's work and have backup instruments, even if just my own senses. Aerospace software is known for relatively low bug counts[1] but also causing fatal crashes[2].

I trust my car controls to be correct and if they aren't I can brake to a stop if anything else seems off. (Unless of course the brakes stop working!) But since you have to take off to fly, you might not realize you can't control the plane until it's already at dangerous speeds.[3]

1: https://www.bugsplat.com/blog/less-serious/why-nasa-code-doe...

2: See https://en.wikipedia.org/wiki/List_of_software_bugs sections on Space, Military, and Transportation for examples.

3: Amazing story about an airliner that took off not knowing its controls had been reversed (a maintenance mistake). Pilots declared "MAYDAY plane is completely uncontrollable we plan to ditch" but eventually figured out how to fly the reversed controls and landed it safely—super impressive. https://www.youtube.com/watch?v=kIc8Rr-cKd8

[tim333]

I think most of that is done automatically by computers in the case of airline jets. For single engine aircraft it's mostly DIY. Though with the jets the pilots get many hours of training on what to do if the various systems / computers go wrong.

[jaywalk]

Believe it or not, weight and balance calculations are not automatic even in the most advanced airliners. The airlines have algorithms they use which spit out numbers that are provided to the pilots, which they enter into the aircraft's computer. These numbers are vitally important, and on one flight I was on we had actually taken the runway but had to taxi back off because Delta was too slow at getting the numbers calculated.

[alanbernstein]

Not that your general point is wrong, but I don't think "flying cars" are intended to replace airliners. They're supposed to be for travel within a city. Complicated calculations for route planning and refueling seem much less relevant for that case.

[shortstuffsushi]

How much weight do you think it would realistically take to alter flight in a plane of this size? For instance, if both the pilot and passenger weighed e.g. 200lbs and sat toward the left of the plane, would that considerably (or perhaps even just perceptibly) impact flight? Same for some of the other variables, is there an appreciable different for things like magnetic variation? Wind, of course, seems reasonable - the others I've heard less about. I don't fly, and have never been in a small engine craft.

[sokoloff]

Fore and aft weight distribution matters a lot in terms of how the airplane flies. Side to side not as much. (Most single-engine airplanes have more moment arm of fuel weight change in the wings than moment arm of two people sitting on the left side of the airplane.)

Fore and aft changes in center of gravity affect how far the center of mass is from the tail control surfaces and the amount of negative lift the tail has to contribute. I can feel the difference when my (fairly small framed) family moves around in the back cabin.

Aft weight distribution makes the airplane far more sensitive in pitch, reduces drag from the tail negative lift, which slightly increases climb rate and/or forward speed for a given power setting.

[pilot7378535]

Not sure about the plane from the original post; it looks pretty hefty. And lateral weight is so close to the center of mass that it's unlikely to have much effect. What's more of a concern is having a bunch of weight far from the plane's center of mass, where the weight tries to lever the plane end over end, increasing the risk of a stall. I heard about a crash where the pilot's seat adjuster didn't lock, so when he took off his seat slid all the way back (just a few inches) but that was enough to cause a crash. Could theoretically happen to any size plane, but matters more with little light planes like those in general aviation.

I have no idea if "Spirit Airlines weight distribution issue" actually happened, but it's funny so I'll share: https://youtu.be/YvfYK0EEhK4

Magnetic variation in my area is +20° (west) off true north. So if I want to follow longitude line true north I need to fly such that the compass reads 20° NEN. And don't forget to account for the hunks of metal inside the airplane, which can affect the compass differently depending on your heading.