Search found 478 matches

  • 1
  • 2
  • 3
  • 4
  • 5
  • 10
by Backseater
Thu Apr 04, 2019 6:41 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

And I hope that somebody at the news conference will ask: "Sir, have you recovered the two angle of attack sensors that were installed on the aircraft? Any pictures?" "Can you please provide their serial numbers?" recovering AOA sensors for high speed nose down crash? If this is...

Jump to post
by Backseater
Thu Apr 04, 2019 5:58 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

And I hope that somebody at the news conference will ask:
"Sir, have you recovered the two angle of attack sensors that were installed on the aircraft? Any pictures?"
"Can you please provide their serial numbers?"

Jump to post
by Backseater
Thu Apr 04, 2019 5:37 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

I know we can trust the media when it comes to aviation as far as we can throw them but now they're saying a damaged sensor caused by a bird/foreign object hitting the plane caused the crash? That seems very odd and implausible unless it took out the pitot tubes or something.... https://abcnews.go....

Jump to post
by Backseater
Wed Apr 03, 2019 3:31 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Well I am worried.
Does anybody know how many AoAs have been replaced among the 70 ac operated by Southwest, American and United?
If any were replaced, what was the disposition of those “faulty” units?
Were they sent back to the manufacturer for analysis?

Jump to post
by Backseater
Tue Apr 02, 2019 10:03 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

I apologize for my clumsy examples which I gladly withdraw. But it looks like there is nothing like a bad post to wake up everybody! The core of my post was: From the UTC flier for the AoA sensor 0861HB certified for Bombardier CRJ /100 /200 /700 and /900: • Fleet MTBF greater than 20,000 flight hou...

Jump to post
by Backseater
Tue Apr 02, 2019 6:51 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

With such information, offering one AoA input, two optional for a fee, would seem like a calculated risk. Boeing did not ever offer an option for two AoA inputs to MCAS -- for a fee or for free. There always (unfortunately) was only one, although with the fix there now will be two going forward. Af...

Jump to post
by Backseater
Tue Apr 02, 2019 5:15 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

These questions are a red herring. We all know, that AOA-sensors fail from time to time. It is a mechanical moving part, working in harsh environmental conditions. This is the reason, why essential safety systems of an a/c shouldn't rely on a single AOA-sensor. The real problem is not, why the sens...

Jump to post
by Backseater
Tue Apr 02, 2019 1:12 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Is there redundancy for the electronic inside the AoA sensors ? I doubt it. 2 EEPROMS maybe? I would write two copies of the configuration and calibration parameters to memory with a hash code, to ensure their validity when the sensor restarts. And if the microprocessor cannot find a good set, it h...

Jump to post
by Backseater
Mon Apr 01, 2019 11:27 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Are the maintenance records for that aircraft good enough to be released: - serial numbers of the AoA sensors installed? (by the way, did they find them in the debris? They should have!) - history records of the AoA sensors (source, repairs, ...) - detailed records of the installation and test proc...

Jump to post
by Backseater
Mon Apr 01, 2019 7:50 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Finn350 wrote:
Preliminary report will be something like two pages stating the basic facts. Maybe in a couple of months time we will get an interim report with more facts.

If it consists of only 2 pages, maybe that’s why they did not want to release it on April fools day! :banghead:

Jump to post
by Backseater
Mon Apr 01, 2019 7:47 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Finn350 wrote:
Preliminary report will be something like two pages stating the basic facts. Maybe in a couple of months time we will get an interim report with more facts.

If it consists of only 2 pages’ m they did not want to release it on April fool day!

Jump to post
by Backseater
Mon Apr 01, 2019 6:34 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Thank you "fadecfault" and "PixelFlight"

Jump to post
by Backseater
Mon Apr 01, 2019 6:01 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Preliminary Report release date changed again. Ethiopia will not release a preliminary report into the causes of last month’s Ethiopian Airlines crash on Monday, as previously expected, but may publish it this week. Ethiopia’s foreign ministry spokesman had earlier said the preliminary crash report...

Jump to post
by Backseater
Mon Apr 01, 2019 4:53 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Incorrect. There are 2 channels on the aoa. One feeds the symd and the other feeds the onside adiru which provides data to the onside fcc. Stick shaker is only activated by the symd. Mcas is only activated by the active fcc. Thank you for your corrections. So, the 861FL1 has another analog channel ...

Jump to post
by Backseater
Mon Apr 01, 2019 3:09 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

In order to elicit any comments and corrections, here is my current understanding of the AoA data path on the 737 MAX:

Image

Jump to post
by Backseater
Mon Apr 01, 2019 1:17 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Boeing can mandate all they want (I doubt they do for anything), the operator will decide what kind of part (new, overhauled, as removed, etc) they want to use. You can remove a known working part from an aircraft, tag it "removed in serviceable condition", and install it on the aircraft ...

Jump to post
by Backseater
Sun Mar 31, 2019 8:11 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

So, if Boeing does not mandate AoA replacement with a new part (I do not know whether they do or don't), the provisioner of an airline always has multiple choices. Boeing can mandate all they want (I doubt they do for anything), the operator will decide what kind of part (new, overhauled, as remove...

Jump to post
by Backseater
Sun Mar 31, 2019 6:54 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

I am currently focusing on AoA sensor technology and part traceability. My concern is that many maintenance teams may have handled AoA sensors a bit too casually, because in the past sensors failed mostly at altitude, for instance by having ingested tiny amounts of water that then froze the bearings...

Jump to post
by Backseater
Sun Mar 31, 2019 12:18 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

((Edited post)) Just out of curiosity, here is a picture of a mechanic checking the AoA sensor alignment on a Lion Air 737 MAX (from Chinese TV network) https://i.ibb.co/rQB9qdF/Lion-Airalign550.jpg I believe he is using a J34002-19 tool licensed from Boeing. I think it works as follows. The tool is...

Jump to post
by Backseater
Sat Mar 30, 2019 4:32 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Just out of curiosity, here is a picture of a mechanic checking the AoA sensor alignment on a Lion Air 737 MAX (from Chinese TV network) https://www.ibb.co/TrQvfFk I believe he is using a J34002-19 tool licensed from Boeing. I think it works as follows. The tool is temporarily attached to the sensor...

Jump to post
by Backseater
Fri Mar 29, 2019 8:48 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Now, does anybody believe that the Lion Air AoA sensor (and probably the Ethiopian AoA as well) failed while accelerating down the runway? I have a strong suspicion that an “unserviceable” AoA sensor was installed and somehow passed the post-installation ground tests. To me, that is a more serious ...

Jump to post
by Backseater
Fri Mar 29, 2019 7:28 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

UTC/Rosemount AoA sensors that are apparently installed on 737MAX are claimed by their manufacturer to be very reliable: “Model 0861 AOA Transmitter. This swept tapered vane angle of attack transmitter: - is aerodynamically aligned, has high reliability, low maintenance requirements and superior per...

Jump to post
by Backseater
Fri Mar 29, 2019 4:23 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

As I am continuing my exploration of AoA issues, I believe the following gives some insight into some possible failure modes of AoA sensors, even if the sensor involved here is not the one installed on 737MAX: In October 2012, the FAA issued a Notice of proposed rulemaking (NPRM) [Docket No. FAA–201...

Jump to post
by Backseater
Wed Mar 27, 2019 9:04 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

MCAS did not just appear with the MAX. Here is a quote from Aviation Daily (25 March 2019): "Both the KC-767 and KC-46 fleets delivered to air forces in Italy, Japan and the U.S. rely on the MCAS to adjust for pitch trim changes during refueling operations. In the 1980s, Boeing’s engineers cons...

Jump to post
by Backseater
Tue Mar 26, 2019 8:03 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

If anybody has access to the Aircraft Maintenance Manual (AMM) for the MAX, I would like to know what the following tasks are and how they are carried out in practice:
- Task 34-21-05-000-001
- Task 34-21-05-400-801
Thanks

Jump to post
by Backseater
Tue Mar 26, 2019 4:42 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Some questions on my side: 1) When MCAS was active during the 10 seconds, is electric trimming on the control column inhibited for that 10 second period? 2) So in that scenario, is electric trimming only available to the pilots during a 5 second window? 3) If control column is already heavy, and th...

Jump to post
by Backseater
Mon Mar 25, 2019 4:47 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

MCAS software implementation must be improved, no doubt. But to be fair, MCAS was designed to handle transient conditions under some extreme regimes. MCAS was not designed to operate on an a/c that IMHO should never have been dispatched in the first place. As I have already explained several times,...

Jump to post
by Backseater
Mon Mar 25, 2019 3:51 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

MCAS software implementation must be improved, no doubt. But to be fair, MCAS was designed to handle transient conditions under some extreme regimes. MCAS was not designed to operate on an a/c that IMHO should never have been dispatched in the first place. As I have already explained several times, ...

Jump to post
by Backseater
Sun Mar 24, 2019 7:15 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Now, if you rotate the airfoil (not the whole assembly!) 180 degrees, the spur would now lie left of the redline. In that case, the range would have become approx. -78deg to 78deg. assuming that each limiting pin spans 2 degrees. Maybe, just maybe, some outfit refurbishes 737NG AoA sensor without r...

Jump to post
by Backseater
Sun Mar 24, 2019 5:35 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Yeserday I proposed that Lion Air (and maybe Ethiopian) may be explained by "an improperly assembled/reassembled Rosemount 0861 sensor that should lead to a 22deg offset once tested and implicitly calibrated by the 737 avionics software)." Let us use one of the pictures posted by "Pat...

Jump to post
by Backseater
Sun Mar 24, 2019 3:24 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

dakota123 wrote:
Apologies; I later corrected myself as my initial source was bad. It’s indeed actually 1:1, or thereabouts.

Based on the trim speeds I wrote in a previous post, IMHO the ratio would be 0.2 / 0.27 i.e.
Pilot trim up speed = 0.74 x MCAS trim down speed.

Jump to post
by Backseater
Sun Mar 24, 2019 6:48 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Yes, ONS must be there to collect a lot of very useful data on the MAX. But in the end, the decision to transmit is always cost, and who is going to pay for it. I dont’t Know whether Ethiopian has high speed satcom onboard but I doubt it. Do their passengers want such service? But for urgent, short ...

Jump to post
by Backseater
Sun Mar 24, 2019 12:45 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sorry but IMHO it does not look like the Rosemount 0861 that is on the 737

Jump to post
by Backseater
Sat Mar 23, 2019 11:51 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

After much reading, I cannot say that I understand the failure mode of the Lion air left AoA sensor, but I have a plausible theory. To me, it would seem like a calibration error (the sensor was following the other one but with a 20-22 deg offset). However, there is no mandatory calibration in the f...

Jump to post
by Backseater
Sat Mar 23, 2019 11:45 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

To push the speculation toward the end stops, I would suspect, that when FAA/Boeing cited ET stab inspection and satellite data for the grounding decision, the data must have included something more that can be gleaned from FR24. Perhaps ADS-B data obtained from the satellite is likely to have incl...

Jump to post
by Backseater
Sat Mar 23, 2019 11:39 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

After much reading, I cannot say that I understand the failure mode of the Lion air left AoA sensor, but I have a plausible theory. To me, it would seem like a calibration error (the sensor was following the other one but with a 20-22 deg offset). However, there is no mandatory calibration in the f...

Jump to post
by Backseater
Sat Mar 23, 2019 6:25 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

After much reading, I cannot say that I understand the failure mode of the Lion air left AoA sensor, but I have a plausible theory. To me, it would seem like a calibration error (the sensor was following the other one but with a 20-22 deg offset). However, there is no mandatory calibration in the fi...

Jump to post
by Backseater
Sat Mar 23, 2019 5:05 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

To push the speculation toward the end stops, I would suspect, that when FAA/Boeing cited ET stab inspection and satellite data for the grounding decision, the data must have included something more that can be gleaned from FR24. Perhaps ADS-B data obtained from the satellite is likely to have incl...

Jump to post
by Backseater
Sat Mar 23, 2019 3:27 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

at Lion the captain correctly countered MCAS fault 21 times, and then by what can only be classified as a complete failure of cockpit communication, transferred flying tk tbe FO to look up a solution without telling him what he had been fighting and what he was doing to stop it. 21 times, but no co...

Jump to post
by Backseater
Fri Mar 22, 2019 3:42 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

My points stands: a fail-safe design needs at least 3 inputs. You're proposing to replace a straightforward 3-sensor data vetting logic (which can nevertheless have it's intricacies: the devil is in the details, ask Airbus about Quantas Flight 72) with an estimator using all other available inputs ...

Jump to post
by Backseater
Fri Mar 22, 2019 1:47 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

It is possible to have fault tolerant software that fails gracefully with only 2 sensors. In fact, Boeing is writing and testing it right now. Yes, this is possible using predictor and filters. In this case the predictor will model the flight dynamic from all available inputs (energy state, control...

Jump to post
by Backseater
Thu Mar 21, 2019 4:35 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

In a post a couple of days ago, I suggested that FAA engineers may want to ask the manufacturer for a clear pseudocode description of the old and of the “enhanced” MCAS algorithms, and I still do. In my simplistic sample pseudocode example I wrote: IF AoA > A0A_threshold THEN … But even for working ...

Jump to post
by Backseater
Wed Mar 20, 2019 10:19 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

It's called a syslog, and everyone in data and telecommunications uses them. I have to wonder though, doesn't the Cockpit have a way of pulling this info? That’s why I am asking. It is such a simple and useful tool in other environments. And if they do have one in the cockpit, maybe MCAS was not de...

Jump to post
by Backseater
Wed Mar 20, 2019 10:08 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Improving the MCAS algorithm is clearly needed. Buy as many posts have stressed, the problem facing JT & ET pilots was to identify quickly enough what was happening, or rather “what had just happened”, MCAS having acted behind the scenes (except for the windmilling stab wheel), probably trigger...

Jump to post
by Backseater
Wed Mar 20, 2019 9:13 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Improving the MCAS algorithm is clearly needed. Buy as many posts have stressed, the problem facing JT & ET pilots was to identify quickly enough what was happening, or rather “what had just happened”, MCAS having acted behind the scenes (except for the windmilling stab wheel), probably triggere...

Jump to post
by Backseater
Tue Mar 19, 2019 7:12 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

I understand the need for protecting against the risk of the AoA progressing towards a stall condition. I think I can correctly guess some parts of the algorithm implemented by the current MCAS software, but I do not understand it well enough to build a replica that what could not be distinguished b...

Jump to post
by Backseater
Tue Mar 19, 2019 12:32 am
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

I was wrong of course, not 30 but 17. The value 240 must also be wrong. Searching more I found a range from 40 to 268.
But I defer to 7BOEING7 with around 50, he is the expert.

Jump to post
by Backseater
Mon Mar 18, 2019 10:57 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Anyone any ideas on this question: What angle rate could one normally expect with hand turning the trim wheel? . . . then it's vital to flick Stab Cut Switch immediately. Now the crew have to revert back to manual trim wheel. What's the normal rate your average pilot can obtain using the wheel? Fro...

Jump to post
by Backseater
Mon Mar 18, 2019 5:42 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

I’l continue on my train of thought. In a modern a/c, I believe that the AoA display is raw, not normalized 0 to 1, with 1 for max wing loading. Why? Because aviation engineers know that Mach nr will be erratic in case of unreliable airspeed causing a normalized AoA that depends on Mach nr to become...

Jump to post
by Backseater
Mon Mar 18, 2019 3:32 pm
Forum: Civil Aviation
Topic: Ethiopian Airlines 737MAX crashes enroute to Nairobi Q1 2019
Replies: 5479
Views: 721906

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

The problem is not just to protect against “AoA fault”.
It is to protect against “AoA > threshold” fault!
And “threshold” is a dynamic value that is probably most related to Mach number.
So, who computes it? And how?
And in the case of unreliable airspeed, what value is used, if any?

Jump to post
  • 1
  • 2
  • 3
  • 4
  • 5
  • 10