Wikipedia:Reference desk/Archives/Science/2022 March 22

= March 22 =

Stillbirth
What could be responsible for a baby dying in the womb? — Preceding unsigned comment added by 2A03:2880:30FF:10:0:0:FACE:B00C (talk) 18:46, 22 March 2022 (UTC)
 * Have you looked at the Stillbirth article? There is also an UK NHS page here. Hope that might help. Martinevans123 (talk) 19:04, 22 March 2022 (UTC)

What are the implications, if an airplane crashes in a vertical nose-dive descent?
Re: China Eastern Airlines Flight 5735. The article states: ... footage depicts the plane in a nose first vertical descent. What is the significance and/or implications of a near-vertical nose-first descent? In other words, what does that "fact" tell investigators? Thanks. Joseph A. Spadaro (talk) 18:49, 22 March 2022 (UTC)
 * Even if all engine power is removed from a Boeing 737, so that any autopilot mode is disengaged, during a straight and level cruise, if the aircraft surfaces remain as set, the aircraft should be able to glide for about 60 miles? A nose dive suggests either catastrophic failure of the control surfaces or that the aircraft has been intentionally flown into that dive profile? Martinevans123 (talk) 19:02, 22 March 2022 (UTC)


 * Hmmmmm ... thanks.  In other words, it could/would be a (possible) sign of a pilot suicide?  Joseph A. Spadaro (talk) 19:32, 22 March 2022 (UTC)


 * I wouldn't like to speculate. But if the aircraft in question hit the ground, such a scenario might not be easily proved or disproved by the FDR data, or even the CVR data. Martinevans123 (talk) 19:56, 22 March 2022 (UTC)


 * Thanks. I am not referring to this specific case, but just to airplane crashes in general.  If investigators see a vertical nose-dive descent ... does that trigger the thought that it's a possible pilot's (or some other on-board individual's) suicide?  Thanks.      Joseph A. Spadaro (talk) 20:03, 22 March 2022 (UTC)


 * Unless the aircraft has been blown up by a bomb, and it's just fragments that are falling, I think vertical descents are rare in plane crashes. But then pilot suicide is also quite rare. Martinevans123 (talk) 20:36, 22 March 2022 (UTC)


 * Based on my extensive expertise from watching airplane accident TV shows, it is very difficult to get a modern airliner to go vertical and remain vertical unless it is deliberate. Also see Suicide by pilot. Clarityfiend (talk) 23:29, 22 March 2022 (UTC)


 * The general description of the crash reminds me of USAir Flight 427, which was a "hard rudder over" event. --←Baseball Bugs What's up, Doc? carrots→ 21:41, 22 March 2022 (UTC)
 * Possibly so. Even that was only pitched 80° nose-down and banked 60° left. Martinevans123 (talk) 22:06, 22 March 2022 (UTC)

Reading the comment above by Clarityfiend made me think of another (somewhat related) question. Is there any valid or legitimate reason for a pilot to deliberately engage in a nose-first vertical descent? Or maybe ascent? Is there any scenario in which that would be "proper" or appropriate? I am not talking about engaging in a nose-first vertical descent, until the pilot crashes (or lands) the plane into the ground or the ocean or a mountain. I guess I mean for a brief temporary time-frame, to avoid some problem or collision or weather or whatever emergency? Would there ever be such a scenario that might call for such a maneuver? Thanks. Joseph A. Spadaro (talk) 00:52, 23 March 2022 (UTC)


 * I was thinking of ValuJet Airlines Flight 592, but now that I found the article, that was due to mechanical failure, not murder/suicide, so ignore the first part of what I said. Clarityfiend (talk) 02:40, 23 March 2022 (UTC)
 * There was also Indonesia AirAsia Flight 8501. While this was more complicated than just a sudden descend, it did involved a stall and rapid descent. The maximum descent rate is only about 2/3 of that of the recent crash however it was still fairly high. I have no idea what the nose pitch etc would have been like during the descent although do find some sources suggesting it may have hit the water nose first. Nil Einne (talk) 04:46, 23 March 2022 (UTC)
 * Some more reading found Alaska Airlines Flight 261: and  and  I also found Atlas Air Flight 3591 it was on approach but did enter what is a called a nose dive. And Adam Air Flight 574:   Some also mention Flash Airlines Flight 604 which is called a nose-dive although at least from the description in our article, it doesn't sound that similar:  Nil Einne (talk) 05:50, 23 March 2022 (UTC)
 * There is also [//www.seattletimes.com/nation-world/japans-ana-co-pilot-error-sent-737-into-nose-dive/] [//japantoday.com/category/national/ana-pilots-unaware-for-20-seconds-that-plane-was-almost-turning-upside-down] although it was only briefly by comparison. Nil Einne (talk) 06:29, 23 March 2022 (UTC)
 * Is there any valid or legitimate reason for a pilot to deliberately engage in a nose-first vertical descent? Not really. At least, not to a point so fast like this that there wouldn't have been any contact with ATC. Even emergency descents (say, due to depressurisation) would not be conducted at a 30000 fpm rate (and consequently, certainly not at a full nose down attitude); and in any case flight manuals recommend maintaining a safe speed and common sense dictates one should retain control of the aircraft while doing so. Modern jetliners are wonderful machines, but they are not aerobatic or fighter aircraft, and such extreme maneuvers are not something the plane is designed for, and even less so of a good idea if there are actually passengers aboard. Short of the pilot deliberately doing so, there do remain some options, such as critical damage to a flight control surface (or it being forced into an inappropriate position); or an in-flight upset, caused either by heavy turbulence or a combination of other factors (makes me think of China Airlines Flight 006 - although the pilots there managed to recover safely, although the plane was badly damaged). The more precise data from FR24 suggests the plane levelled off, at least momentarily, but without information regarding it's bank angle or pitch at that time, it is impossible to know whether this was simply the trajectory followed by an otherwise uncontrollable plane, or whether it was an unsuccessful attempt by pilots to regain control, or even if this was indeed a suicide by pilot and somebody was trying to wrestle the controls from him. RandomCanadian (talk / contribs) 05:13, 23 March 2022 (UTC)


 * In the above post, RandomCanadian uses the term FR24. What does that refer to?  Is it a flight?  A flight recorder?  What do the letters (FR) and the numbers (24) stand for?  Thanks.    Joseph A. Spadaro (talk) 17:58, 23 March 2022 (UTC)
 * @Joseph A. Spadaro: Flightradar24. 199.208.172.35 (talk) 19:40, 23 March 2022 (UTC)


 * Looks like it was about to approach destination airport, and I heard (unconfirmed) there were 3 crew members on the flight deck, it also briefly leveled / climbed, so this might not be intentional, or maybe a fight/struggle among the pilots, or something that disabled the entire crew, but don't quote me on this. A bad stall that's not recovered from could end up in a nose dive, especially if the control surfaces create more drag to the rear of the airframe. Although from 30 K, with enough airspeed, as long as you have controls, there's a fair chance of recovery. I find the lack of reporting of any radio communication quite strange however. GeorgiaDC (talk) 09:23, 23 March 2022 (UTC)
 * If the "black boxes" managed to survive the impact, they might tell the story. Whether the Chinese government sees fit to reveal that story, remains to be seen. --←Baseball Bugs What's up, Doc? carrots→ 11:43, 23 March 2022 (UTC)
 * The one box they have found is so badly damaged it's unclear if it was the FDR or the CVR. Whatever story it does tell might well be ambiguous. But I think it's highly unlikely we'll get to see any personal information on the pilot or other crew. Martinevans123 (talk) 11:47, 23 March 2022 (UTC)
 * Reports say it actually had 3 pilots. FR24 charts. Plane doesn't appear to have stalled. Looking at the vertical rate, there appears to be attempt to reverse from dive to climb, over 60 sec or so. Combining ground and vertical speeds, the actual dive wasn't necessarily straight down, more like 45 degrees. Here's angle 1, appears almost vertical. But here's angle 2, less vertical. Of course, a lot talk at this point about angle 1, but it could be misleading. I also can't make out any wings, blurry as the footages are. GeorgiaDC (talk) 23:00, 23 March 2022 (UTC)

Thanks, all. Joseph A. Spadaro (talk) 20:30, 27 March 2022 (UTC)