Not at all. Indeed the p value (if one is to use the dreaded p value in order to accept hypothesis) should be adjusted and fairly small. In essence, we could go in blind over all data available, but adjust the p value according to degrees of freedom available to avoid false positives.

Now given that the flight data sample is huge (say, all flights in the past 3 years), the probability of false positive is actually small anyway. So is there a statistically significant difference between # of flights that did/didn't crash in the group of flights which are Boeing in low visibility on final/approach?

And btw, picking a hypothesis up front makes no difference. Imagine 20 different statisticians would decide to test a hypothesis over flight data, each unbeknown and independent of each other. Each would choose a different parameter, but p of only 0.05. Those results would not be different, but there would indeed likely be at least 1 false positive due to stupidly large p value (0.05 is really astronomical when you think about it).

ADS-B data from FR24 gives GPS derived speed, which is the ground speed, i.e. the speed of the aircraft in the horizontal plane only as seen from straight above. If you're tossing a stone off a tower by throwing it away from the tower, it will retain most of the forward velocity but vertical velocity will continue to increase until it hits the ground, thus creating parabolic flight path. An aircraft without (sufficient) elevator authority will do the same. The impact velocity is far greater than the horizontal velocity would indicate, it's the vector product of both the horizontal and vertical speed components.

Lion Air was a very different case. Fly Dubai and this Atlas crash look a lot more similar in the end phase - which bears absolutely no meaning on the root cause. All it says is: elevator authority was impaired. Period.

Going to be lots of human factors focus here. Interactions between pilots, between controllers, between pilots and controllers.

Why the CA/PF was on the radio descending through 17,800' when Approach cleared them for the 26L transition (they were actually told that they "can" fly the 26L, pilot appeared to say "91" but did not read back the transition change).
What was the FO/PM working on.
Why they were approaching RDFSH at 6000' and not GARRR at 7000' (sure, Approach thought 3591 was deviating for weather, although they hadn't cleared them for it, and Approach didn't ding them for being at 6000' instead of 7000' for GARRR).
Why the constant 240KTS in the descent with the parabolic drop-off at the end, were they in speed mode, what altitude was set.
Did they have a high rate of descent result from pulling power while trying to decelerate, did the 30,000 FPM final rate of descent result from a departure from controlled flight-- maybe with parts coming off-- in the effort required ("PULL!") to bring the nose up from 18,000 FPM through 11,000 FPM, which is where the bottom fell out.

Not throwing stones here. I live in a glass house of my own making. Just looking for the most obvious/likely causal factors. Occam's Razor. Whatever you do, don't ask how I can envision this scenario happening.

I've worked through it a number of times and have a more lengthy write-up, that is, if you want some more conjecture as to what happened. Guys just out trying to make an honest living, and the whole thing went to hell on them. Whole thing makes me want to puke.

Yes, although the aircraft's trajectory, with at least some thrust being generated, would differ slightly from the purely ballistic trajectory of a thrown stone.

The last few points of the ADS-B data would suggest a flightpath angle approaching -50° and a resolved velocity approaching 400 kts at the last recorded point. That's consistent with the relatively small debris field.

:ugh: Of course! How could I have missed that. Sorry!

I really don't want to argue with you, but using a tighter p-value is no cure for improper statistical design. You have no model for the distribution of the errors because you chose a hypothesis to fit your limited choice of data. Indeed, the hypothesis you chose fit the data exactly -- so you have a degenerate error distribution. Further, you seem to have a very limited view as to what the relevant data are. For example, the XL Air crash at Perpignan was also a nose-over -- but that was a A320. Your "model" cannot explain that at all. https://en.wikipedia.org/wiki/XL_Air...ny_Flight_888T

There a loads of reasons for this, PM could have been on the other radio talking to Ground services/company or updating the new weather, or anything, how many times in a flight do you end up saying "can you just take "one" a second while i do XXXX"

Actually, what Chairman Sumwalt said is that the main wreckage is approximately 200 yards long by about 100 yards wide. Perhaps he implies that the packages and aircraft parts are scattered over a wider area.

See his comments at 4:46 in the NTSB media conference video:


Here's cellphone video of the debris field on the Chambers County Sheriff's Office Facebook page:

https://www.facebook.com/watch/?v=2305590612836823

I know nothing about the 767 stabilizer and elevator system, and I realize this is a completely different type of airplane, but does anyone remember what happened with Alaska Airlines Flight 261 and the jack screw assembly?

https://en.wikipedia.org/wiki/Alaska...nes_Flight_261

your examples also share other characteristics:

1. built after Dec 17, 1903
2. had paint on the outside
3. had people and stuff on the inside
4. took off
5. had wings
6. had engines

yep, theres a definite pattern there.

FZ981 was a disorientation event following a GA in wind shear.
Lion Air 610 has indications of sensor failure leading to loss of control for unknown reasons at this time.

FZ approach was not low viz, with an GA due wind shear according to the interim report. Fedex was at 6000', starting the approach, and the weather at the field itself was clear, the line of weather on the approach that the aircraft entered was well away from the airport.

I wasn't "trying" to hear it....
 

I did hear it. You are right about the possible context......but given the timing of the crash relative to that word heard, I'd be comfortable making a $20 bet, it wasn't anything to do with a seat belt.

AZ261 MD80 aircraft had a single screw jack, the B767 has dual jacks which are independent, except that they share structure at the fuselage attachment, which was the subject of AD's in the past related to cracking.

@ FDR Thanks for your response.

Here is the "proposed AD

" ....in 2000"On January 31, 2000, there was an accident involving a McDonnell Douglas Model DC-9-83 (MD-83) airplane. The National Transportation Safety Board (NTSB) determined that the probable cause of this accident was a loss of airplane pitch control resulting from the in-flight failure of the acme nut threads of the jackscrew assembly of the horizontal stabilizer trim system.
The NTSB concluded that the thread failure was caused by excessive wear, resulting from insufficient lubrication of the jackscrew assembly.Start Printed Page 58621The drive mechanism of the horizontal stabilizer on McDonnell Douglas Model DC-9-83 (MD-83) airplanes has a jackscrew assembly with an acme screw.
The drive mechanism of the horizontal stabilizer on Boeing Model 767 airplanes uses a ballscrew. Acme screws and ballscrews have some differences in design, but perform similar functions and have the same airplane level effect following failure. The manufacturer's safety analysis of the 767 drive mechanism found no safety problems with the configuration of the drive mechanism, but showed that changes to the maintenance procedures and maintenance intervals are required to keep the drive mechanism properly maintained and operating as designed.
We have received a report indicating that the ballscrew in the drive mechanism of the horizontal stabilizer on a Boeing Model 757 series airplane showed extensive corrosion, which could lead to excessive wear. The ballscrew on Boeing Model 757 airplanes is similar to that on Boeing Model 767 airplanes that are the subject of this proposed AD. Therefore, both of these airplane models could have the same unsafe condition.
We are considering separate action for the Boeing Model 757 series airplanes and other similar Boeing airplanes.Extensive corrosion of the ballscrew in the drive mechanism of the horizontal stabilizer, if not corrected, could cause an undetected failure of the primary load path for the ballscrew and subsequent wear and failure of the secondary load path, which could lead to loss of control of the horizontal stabilizer and consequent loss of control of the airplane."

Are you positive about the 767 having dual jacks? I'm pretty sure there's only one screwjack ( although there might be concentric load path redundancy in the event of a failure) with dual hydraulic motors/brakes. It's been a few years since I've flown it, though...

Correct. The 767 only has one ballscrew. However, it does use two hydraulic motors which drive the single ballscrew through a differential gearbox.