Lion Air 737-Max missing, presumed down in the sea near CGK (Jakarta)

[BoeingBobby]

Why? 5K hours and 300K cross country flight gives you an average of exactly 1 minute per cross country flight (if all the 5k hours were used for cross country). Anything remarkable there?
(let me bet it's a typo and the 300k should be 300)

The 5000 hours is not unheard of for GA instructors. If you instruct 4 hours per day 150 days a year you make it in 8 years. Let me guess the guy is slightly more than 30 y/o.

Thought he was saying 300000 hours cross country. Remember Gabe that I also have a commercial glider rating.

[Evan]

Thank you. I would say that a sudden change from about +2500 fpm to about -3500 fpm in about 20 seconds (that's -6000 fpm per second or -100 fps or an acceleration -3.1g which corresponds to a load factor of -2.1) would be a sudden, very likely uncompounded, fall. And since it happens 3.5 minutes after lift off with the plane barely above 5000 ft, I would say that this qualifies as shortly after take-off too.

Would maintenance have downloaded the FDR from the previous flight to troubleshoot this? Would they have a record of that? One key question here is whether they were on autopilot when the sudden plunge occurred. An undetected air data anomaly can cause this to happen on autoflight, as it did on those Qantas A330's and that Malaysia B777 some years ago. Boeing does have a history with shady cross-comparator behavior on avionics. Turkish 1951 experienced a cross-comparator fail on the autothust unit which led it to rule a single malfunctioning radalt valid and retard thrust way... too... early...

[pegasus]

The K in 300k is kilometres.Once you have been bitten by the gliding bug, the challenge is to fly cross country to a pre- determined turning point. In the case of 300k, the point will be at 150k and then to return to base.Typically,on a good day when thermals are strong, with a cloudbase of 4/5000ft you would hope to accomplish the task in less than 5 hours. I hope that this makes things clearer.

[Gabriel]

You have mentioned, I think, that on a conventional aircraft with control feedback, you can fly by letting the aircraft speak to you, by feel, as opposed to following UAS pitch/power procedure and QRH values.

You took short excerpts of 3 totally different comments that I made, mixed them together, put them totally out of context, and voila!!!

On the other hand, forget STS. What happens when you are without reliable airspeeds and you decide to depart level pitch/power flight, to enter a turn back to base, when you are flying 20kts slower than you think?

When you are flying at more than 300 kts? Nothing. I am more concerned with overspeed than with stall here.

[Gabriel]

"5000+ hours) instructor rating and more 300k+ cross country" Now that is impressive! A touch unbelievable too!!

Why? 5K hours and 300K cross country flight gives you an average of exactly 1 minute per cross country flight (if all the 5k hours were used for cross country). Anything remarkable there?
(let me bet it's a typo and the 300k should be 300)

The 5000 hours is not unheard of for GA instructors. If you instruct 4 hours per day 150 days a year you make it in 8 years. Let me guess the guy is slightly more than 30 y/o.

[BoeingBobby]

"5000+ hours) instructor rating and more 300k+ cross country" Now that is impressive! A touch unbelievable too!!

[pegasus]

I hesitated before sticking my neck out and posting. My flying experience is mainly in gliders ( 5000+ hours) instructor rating and more 300k+ cross country flights than I can count.I have seen many young men use their gliding experience as a stepping stone to a career in civil or military aviation.In many cases they have reported positive feedback from their professional instructors in terms of their flying skills and especially in terms of their sensitivity to and to the control of the the attitude of the aircraft. In this accident ( ok not proved yet) and in others,for example AF447, when systems fail the pilots involved seem unable to call upon the basic skill of establishing and maintaining their aircraft in a stable attitude giving themselves time to sort out the systems problem.

I acknowledge freely that the " systems" and the pilots mastery of them have contributed enormously to today's remarkable standards of flight safety. I suppose that I am asking, in the extremely rare event of the systems failing, if the training equips the pilots to revert to basic principles.

[Gabriel]

https://www.flightradar24.com/blog/f...-flight-jt610/

Thank you. I would say that a sudden change from about +2500 fpm to about -3500 fpm in about 20 seconds (that's -6000 fpm per second or -100 fps or an acceleration -3.1g which corresponds to a load factor of -2.1) would be a sudden, very likely uncompounded, fall. And since it happens 3.5 minutes after lift off with the plane barely above 5000 ft, I would say that this qualifies as shortly after take-off too.

There were testimony from different passengers saying that the plane suddenly started to fall out of the sky and that they thought that was the end and all these typical comments that normally don't mean much in the sense of reliable data for an investigation, but some times it does if it is consistent with other hard data.

One could say that perhaps this was the result not of a real fall but of a false altitude and vertical speed indication caused by unreliable air data, but the way the GROUNDspeed varies during the incident makes me think this was not the case.

If the plane really experimented an acceleration anywhere close to that, it should have been grounded for a through inspection since it exceeds the required design limit load by quite a bit.

[3WE]

What happens when you are without reliable airspeeds and you decide to depart level pitch/power flight, to enter a turn back to base, when you are flying 20kts slower than you think?

The aircraft might respond with a fairly typical and not overly sudden phugoid behavior- in particular the behavior normally associated with turning while a little slow.

Electrons shoot through the windows at near-light-speed hitting carbon-based analysis systems which are reasonably good at determining attitude.

Laws of physics, including FAMILIAR power, attitude and performance settings remain unchanged.

AOA-based stall warning systems remain functional.

[Evan]

I don't remember. The wording was not "uncommanded" but sudden, there are reports in avherald about the problems they had with the airspeed and altitude data, the STS, and the control feel system. The FDR that contains 1800 (!!!!) parameters for the last several flights will probably tell.

Big distinction between "sudden" and "uncommanded"... I will be very surprised if anything here was uncommanded. There's had been a lot of chatter about STS. That system has been around on the NG's without ever causing anything like an uncommanded sudden loss of altitude.

STS basically uses the autopilot servo on the (antiquated and overly-complex) elevator to add a small bit of opposing trim force, to compensate for things like underslung thrust at high power, light weight and aft CoG. It was needed to certify the NG, to meet the FAR requirement for minimum trim force. It's not HAL9000.

If STS were "operating in the wrong direction", it would be subtracting required trim force. You have mentioned, I think, that on a conventional aircraft with control feedback, you can fly by letting the aircraft speak to you, by feel, as opposed to following UAS pitch/power procedure and QRH values. Perhaps this crew also felt that way. Perhaps they also failed to realize that there are stealth factors on modern (and awkwardly modernized) jets that the engineers took into consideration when they wrote those procedures, and thus they should always be adhered to for reasons you might not be aware of...

On the other hand, forget STS. What happens when you are without reliable airspeeds and you decide to depart level pitch/power flight, to enter a turn back to base, when you are flying 20kts slower than you think?

[Black Ram]

Are we ruling out rudder hard over - it is a 737

I think investigators have already ruled it out, per the preliminary analysis of the FDR. But I don't know that for sure.

[Black Ram]

Where is that coming from?

https://www.flightradar24.com/blog/f...-flight-jt610/

[Black Ram]

https://www.bloomberg.com/news/artic...n-737-max-jets

All of a sudden we are talking about faulty AoA measurements?

[Gabriel]

Where is that coming from?

I don't remember. The wording was not "uncommanded" but sudden, there are reports in avherald about the problems they had with the airspeed and altitude data, the STS, and the control feel system. The FDR that contains 1800 (!!!!) parameters for the last several flights will probably tell.

[Gabriel]

Are we ruling out rudder hard over - it is a 737

We are not ruling out that... or meteorites.