andrewducker | Interesting Links for 13-05-2022

The SIDS result may not be that useful.

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This is a really promising finding!

I think it's worth the caveat, the study's numbers do not so far show this butyrylcholinesterase assay being useful in screening for SIDS risk. But looking further along this line of work could lead to other measurements that can make a useful test, or possibly even treatments.

Why am I saying not so far shown to be useful? Table 1 and this plot: the two populations (SIDS cases and controls) overlap a lot in BChe levels.

Attempting to use this for screening, if we set a threshold to detect 50% of SIDS susceptibles (50% miss rate, not great obviously), and screen 100,000 U.S. newborns, we'd catch 16 SIDS susceptibles, miss 16, and also flag 23,000 others incorrectly as susceptible. Of the positive tests, 99.93% are false positives. Not useful as-is to parents or doctors. But this paper will surely spark a lot of research.

(By my math: SIDS median 5.2, which is 23% of the way up CDF for the control's 7.7 ± 3.6 sigma.)
posted by away for regrooving

https://www.metafilter.com/195304/Researchers-Pinpoint-Reason-Infants-Die-From-SIDS#8247103

Why are we not using genetic engineering to make new fruit out of currently inedible precursors? We have such a small sample of possible fruit space, and it would be way less risky than buggering about with things that currently by and large work. If you accidentally make a toxic gualtheria berry it doesn't matter because we weren't eating them anyway, but if you can stop them tasting of hospital disinfectant and make them six times bigger they might be great.

It depends on the aircraft.

We'll talk about that, and some interesting boundary cases, in a moment.

It also depends on knowing the flight manual, or having someone on-hand who does, and has sufficient experience as an instructor to 'talk you down': and that person isn't me. I've never flown solo and I've only ever landed a glider under instruction...

But I spent many years listening to entertaining breakfast-table stories from student pilots; and, a few times, this type of story has come up.

The answers aren't reassuring, even for the extreme case on the 'safe' side, the Antonov An-2. It's a postwar Soviet biplane intended to support forestry work in undeveloped areas of Russia, and it's probably the slowest aircraft ever to go into commercial service.

It might actually be the slowest aircraft, ever, unless we talk about hot-air balloons.

It has no published stall speed, and the flight manual tells you that if you haul back on the stick all the way, it will descent 'at parachute-descent speeds' and you will survive the landing, even if the undercarriage doesn't.

Even with the full 1-ton payload or 12 passengers: this is a real, honest-to-god grown-up aeroplane in commercial service and thousands of them are still flying.

Not in 'The West', though, because there are none of the modern navigational aids required for an airworthiness certificate.

It's a very forgiving aircraft with, I am told (and I should check this), very slow and predictable control responses.

I'm a little alarmed that the light aircraft used in that story was, in the pilot's experience, so jumpy: I'll put that down to his total inexeperience... But it might be generally true of all light aircraft: even basic trainers.

So it may well be that the nervous and tense overcontrols and overcorrections of a complete novice place a safe landing out of reach (or, at least, at very high risk) in even the most forgiving and predictable of light aircraft.

Let's not take this to the extremes of (say) a high-performance private jet. They do have the slow landing speeds required for short fields, and you might land it safely if you can line up on a long, wide runway with zero crosswind: but if it happened to me, I'd ask the Control Tower for a heading to one of those dry lake beds they have in Nevada.

Assuming I'm in Nevada.

I don't think I could line up on a runway, maintain my heading, and manage a safe descent - even with a continuous talk-me-down from. an instructor taking me from instrument to instrument (horizon, attitude, airspeed, altitude) and guiding my actions on the controls: there is so much to do, all at once, and I do not believe that I can do them all at once without practicing the necessary aircraft-handling skills until they are down to the 'reflex' level where I'm no longer thinking of my actions on the controls, I'm thinking of the aircraft.

There's a well-documented number of hours' of flight instruction and practice that is known to be required in irder to get there, and I haven't put those hours in.

I haven't put *anything like* those hours in.

...And that's for basic training aircraft, which are designed to support the skills-development of inexperienced pilots.

Modern commercial aircraft are another matter. Some of them do indeed land themselves, but that needs some setup work (no flight is completely hands-off) and the pilots I've asked were very doubtful, or even dismissive, of the idea that a complete novice could safely engage the auto-landing systems.

So now we come to the extreme (ish) case of the most common passenger jet in revenue service: the Boeing 737. It has a very, very high landing speed and the consensus among pilots and instructors is that only a lottery-winner's luck would let a novice never-taken-the-controls non-pilot land it and walk away.

Edited (Spelling) 2022-05-15 09:27 (UTC)

Interesting Links for 13-05-2022

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"Hello Control Tower... Can you help me land this thing?"

Re: "Hello Control Tower... Can you help me land this thing?"