Lufthansa Cargo B772 unreliable airspeed
 

Saw this on AV Herald (link)Not a pilot. What might cause the discrepancy between the altitude that ATC was showing versus what the plane's standby altimeter and GPS were showing. Which instructions/reading should the crew follow? Don't know if they were in IMC or not.

The three altimeters are using different sources I assume (not a 777 pilot).
Standby and GPS ALT was around 6.000 ft, MAYDAY declared, which means they were well above sector altitude and ATC kept the airspace clear.

The ATC value is probably the value that has been encoded and sent by the transponder (secondary radar information is based on the information the aircraft sends to a ping). If the static source/s involved are giving the transponder duff info (a combination of sensor fault, icing, water ingress, FMS super brain fart, unlucky Tuesday), then ATC is not telling the crew anything useful. If the satellite signal generated altitude and standby altimeter correspond, then I‘d trust that, especially as nobody would be expecting to talk to ATC at 200ft.. or suddenly find themselves there!

The last sentence In the article about the ADS-B data saying that the aircraft did not get above 250ft for the entire flight is just a reflection of the same info that ATC was receiving and reporting, low just a reflection of the fault.

Flying at 200 ft around EDDF means your aircraft is in a subway tunnel.

Occam's Razor might offer a more mundane/simple explanation than the above combination, given that the aircraft had spent the previous 6 days on the ground.

Well if that is true, somebody is going to feel very silly.

Not the static covers
 

FYI
It was not the Static-covers....
investigation is ongoing and will be published in due course....

Unplugged static drains inside the cabin?

777 uses flush-mount "salt shaker" static ports on the side of the fuselage to measure static pressure - there are no 'static covers' as such. Although they are sometimes taped over (and the tape left on) :eek:

Boeing had thought that it had found an engineering solution to the problem of unreliable airspeed with the development of the FT-ADIRU. The original QRH entry for unreliable airspeed was just a condition statement as the "box" should have taken care of the problem. If its not an issue with the static ports then possibly it is a result of a software failure in the ADM or FT-ADIRU.

BFU has published an interim report. It is accessible (in English) onr their website and the AvHerald features a decent summary.

Extract:

QUOTE

The examination of the airplane after the landing showed that the connecting lines of the left and right static ports were not linked with the respective ADMs (Fig. 5).

The maintenance work taking place prior to the flight included opening the pneumatic lines, flushing them with dry air and closing them again. The subsequent leak test and system test were meant to ensure proper function of the pitot-static system. On the respective job cards these tasks had been signed as performed and released.

UNQUOTE

While the report gives some details on the individuals involved, it is not clear which organisation achieved this; Lufthansa or Lufthansa Technik. Hopefully the final report will go beyond that and try to identify the systemic cause involved, if any, and not stop to protect the reputation of some well established organisations, including Lufthansa, Lufthansa Technik and LBA. This is common belief in Germany that they are infallible and there is no need for proper oversight.

The BFU report:

(could not include it in the previous post, as I was just short of the 10 posts threshold required to include URL)

What surprises me, is the radio altitude reading being at 0 throughout the flight on the chart. Is the RA disconnected at LH until 2500ft in descent?
If ATC told them they read 200ft all along, a quick check of the RA might help. Or am I completely off on this?

I know, it was more of a rhetorical question ....

"In almost all cases, the display of radio height ceases when an aircraft climbs through 2500' above ground level (agl) and recommences when it descends through 2500' agl. This is confirmed visually by the appearance/disappearance of an 'OFF' flag and emergence of a pointer from behind a mask or activation of a digital display."

.... and therefore i am still wondering about the chart RA readout ......

The RA readout scale is the brown one to the right. It indicates 4000ft most of the time.

Now i got it, thanks!

Good job by the pilots. As always recognition is the hardest part. Looks like they got to 300kts with the flaps out! Be interesting to read the full report and see how effective the relatively new checklist was. Sounds like the standby ASI may have been reading correctly? And perhaps standby ALT as well. And radalt works below 2500ft.

Is my understanding correct that is was the electrical plugs that were not inserted? What kind of transducer is this? Strain gage? Is there no self test programmed in to the box that makes sure on startup that the ADC readings are in the expected range?

Not connected static pressure lines

Look here

Ok, so that red thing with the bayonet type plug is really a hose, not an electric line?

Exactly.

The left picture makes it very clear. You can also see the counterpart, connector at the metal box.

Both technicians have been fired. This is unbelievable. This would have not happened prior COVID 😷.
This goes against any safety culture or just culture. Terrible reaction by Lufthansa Technik management.

At least the technicians and pilots are standing together on this.

in German
https://www.aero.de/news-38363/Pilot...Techniker.html

Appaling. I'm sure last word is not spoken. Labour law is a hard nut to crack in this country.

Tricky one is this.
1. Whoever signed for the refitting of the hoses, must have been convinced that the hoses had been refitted, either because someone else was tasked with fitting them and didn't or he/she was doing the job them selves and for some reason convinced themselves that they had done it. That is a maintenance error and in a busy maintenance environment it can and does happen (there for the grace of god etc). A just culture would investigate and determine why the inspector did not inspect. Was a duplicate inspection required?
2. The leak test post fitment. Was that a requirement? If they are quick release fittings is an external pressure test required? If it is and someone signed it off without performing the test then that is another story.

I would like more info on this before passing judgement. Procedures are there for a reason, we are not paid enough to take chances, well i'm not anyway.

Important to note is the quotation from the pilots letter:
"Wie wir vernehmen mussten, führte dieser Zwischenfall bereits zu Beginn der Untersuchungen zur Entlassung zweier Mitarbeiter der Lufthansa Technik, welche die Arbeiten ausgeführt hatten"
Which I would like to translate as:
"As we had to learn, this incident lead to the release of two Lufthansa Technic personell who had executed the work, already at the beginning of the investigation."

So the from the letter it seem the first priority for the management was to sack the mechanics, even before the incident was fully investigated - which is probably the root of their fury.

Interesting that gps alt readout was available.
Although it’s a function of the FMS and is running “ behind the scenes” I didn’t realize it could be read on a cdu on the 777., unlike Airbus which displays gps alt.
Perhaps it’s a question of operator,s options on the display and what they are prepared to pay for ?

I think you can also get an altitude readout on the CDU of the A320 via the data page. Having it on the PFD is obviously the better solution though.

I don't know about the timing, but if someone signed off that the work had been done and checked/inspected, that could be considered willfully falsifying records.
That would get you canned from lots of jobs...

Check Airman

Yes I think you are correct for A320/330/340
via data page gps alt is available on the cdu.
although it’s been a while .
For 777 as far as I know, it’s not possible to read the gps alt on the cdu on any page , never saw it on the PFD on any a/c. Standing by for more technical heads to advise.
I only mention it because a previous post refers to gps alt as 6200ft , which corresponded broadly with the stby. altimeter apparently.
If gps alt was readily readable it could be a great help when faced with air data issues .

tdracer

As far as I understand, this was an honest mistake. And it was their mistake. But just that a mistake. Why was that mistake made? That is the question. If they acted carelessly of course retraining and disciplinary action is necessary. But not sacking. There are many ways to do this. In Germany we have a "Abmahnung" bit like two strikes and out.
We are all proud of the safety culture we have in our Company. It is something that, even tough Management and employees have had tough battles over the last years, has always survived and been left untouched. I find it disgraceful to treat these guys and our safety culture like this. It just sets a really bad example. Wasn't there a loader who damage the cargo door on the DC-9 but Did not report this because he was scared of the consequences and the plane crashed or received serious damage because of this?
I just get the feeling that prior covid the reaction would have been different. Even when other technicians crippled the 747-200 or broke the nose wheel on the 747-400 nearly killing the push back driver nobody was fired.
It is just a bad management.

Full facts
 

We don't have the full facts around this incident. It is also quite possible, as a result of German privacy regulations, that we will never get the full facts.

I can certainly conceive of scenarios where immediate firing would be appropriate: for example, if management had unimpeachable evidence of collusion between employees to subvert a safety process for personal gain. Note I am NOT saying this is what happened - just pointing out that there can be occasions where instant dismissal is the correct thing to do.

On the other hand, firing first before finding out the relevant facts is something to be discouraged. Sufficiently serious cases might warrant suspension pending further investigation, but summary dismissal should only be used where cases are legally watertight. Such occasions are quite rare.

I can well understand the all too common failing of forgetting to reassemble something. Someone I know had the interesting experience of having a wheel on their car changed by a garage and subsequently discovering on a motorway that the wheel nuts had only been made finger-tight, rather than fully torqued. This is why independent checks and test procedures are so important. If you are interrupted in the middle of doing something, it is easy to skip a step, especially if you are focussed on the goal, made worse if you are tired and/or under time pressure (which may be self-imposed). Plumbers have been known to forget to solder up joints that are subsequently overlaid by plasterboard and paint, and only when the system is first used is the mistake found. It happens. So there could well be many reasons why this failure occurred, so human factors experts do their best to design processes that make things easy for humans.

In short, my mind is open on this: there could be a good reason for summary dismissal, which we might never know: or it could be a visible failure in applying a just culture. We have no idea currently, and we may never know.

Micky
First off, it's one thing to self report that you do something wrong - yes, that needs to be encouraged. But that's not the case here.
But what really gets my attention is not that a mechanic forgot to do something - that happens - that's why we have inspectors. But how does an inspector inspect the job without recognizing it wasn't done? That makes me think that he didn't check, and if that was the case, it's pretty unlikely this was the very first time he signed off as checking a job when he hadn't in fact done that.
For an inspector - yes, that should get you sacked because it demonstrates a lack of integrity. It can also get people killed.

This from Die Welt 23.1.21
Deepl.com translation

In a letter to management, 220 pilots criticized Lufthansa Technik's handling of errors. This was triggered by a maintenance breakdown on a Boeing 777 freighter, which resulted in an emergency situation.

The incident is unprecedented. A good 220 pilots of the cargo airline Lufthansa Cargo criticized their own management in an open letter. It is about Lufthansa Technik's reaction to the faulty maintenance of a large cargo aircraft in October.
Among other things, the pilots are angry that the two technicians responsible were fired. The maintenance errors had led to a serious incident that first became known after a report by the Federal Bureau of Aircraft Accident Investigation (BFU).
According to the report, the crew of a large Boeing 777 freighter operated by Lufthansa Cargo noticed faulty airspeed indicators shortly after takeoff from Frankfurt. They declared an air emergency, meaning a severe and immediate danger.
It was the aircraft's first mission after routine maintenance. Because the Boeing was fully fueled for a flight to China, fuel was dumped for half an hour to reduce landing weight. After the landing, which went smoothly, it was discovered "that the left and right static system sensors were not connected."
Obviously a maintenance error. In addition, a second technician acting as an inspector had stamped a system test as having been performed and approved, supposedly without complaint. In fact, sensor cables were not connected.
The pilots' protest letter, which is available to WELT, criticizes Lufthansa Technik's handling of the errors. "Regardless of the exact circumstances and the internal state of the investigation, we would like to express our concern about the dismissal of the two technicians in no uncertain terms," it says. It is important to deal constructively with mistakes, it said. What is needed is a "healthy, goal-oriented and therefore sustainable error culture". The dismissals should be withdrawn.
When asked, Lufthansa Technik "basically does not want to say anything" about the ongoing investigations. Personnel issues are not discussed publicly, the company says. Aviation security is the focus of the company's work.
Industry insiders point out that it is the second significant incident following faulty maintenance work in the Lufthansa Group. In April 2019, a Global 5000 jet operated by the German Armed Forces Air Force nearly crashed in Berlin.
At that time, according to the investigation report, "manual errors during installation and adjustment work" on the jet's controls caused the near crash. These installation errors also went undetected by the investigator at the time. No details are known about the personnel consequences at the time.

tdracer

+1 on this, I use the James Reason just culture model regularly. Clearly, we don't know all the facts but based on what's in the public domain.

Mechanic performing the inspection
1) Investigation complete
2) Question, was there a conscious substantial and unjustifiable disregard for risk? Answer YES, IF they signed off the work without conducting the inspection.
3) Question, was there malicious intent for the consequences? Answer, NO (hopefully) therefore the flow chart comes out as "recklessness" which could well result in dismissal.

Mechanic performing the task
1) Investigation complete
2) Question. was there a conscious substantial and unjustifiable disregard for risk? If the answer is YES then the flow chart will lead to "recklessness" which could well result in dismissal, if the answer is NO then the flowchart would lead to "mistake" which would lead to a written warning at worst. I imagine that signing a job card to say the task has been completed has led their employer to select YES to the initial question leading to their dismissal.

Using a just culture model properly should take the emotion out of the decision. I have dismissed people in the past by following the model ..... but the model has saved people who would have been dismissed had the model not been followed. The buck for this incident should not stop at the "shop floor" as it appears, on the surface of it, that the safety culture in LHT may need some work.

And a lot depends upon the environment and background, for instance staff experience, workload, Bundesliga, management pressure to get the aircraft out of the hangar etc. The current actions have been taken by Lufthansa Technik, but they might have a clear conflict of interest.

Hopefully the BFU will perform an Annex 13 investigation with a full report.

Going on the engineers threads. OEM muck up. A pitot static system if disturbed need a leak check regardless of the break point. Common sense. It needs an independent inspection. Common sense. The panel closed up after the job done required an inspector to do a clear to fit, fod and integrity. Not carried out. Common sense. 3 people that should be interviewed and if just culture proves they are in violation, disciplined. That simple. There is gash practices in place. I have dragged a MRO in crisis with MOR findings.

Jack D

The FMS is processing both lateral and vertical information primarily from GNSS data. This source data should be retrievable on any system (e.g. sensors status page or such). It is also not bad practice to check your QNH against this when doing LNAV & VNAV approaches. Similarly a crosscheck of the signal during an LPV approach can be made.

Normailly radar altimeter altitude is maximized at 2500 ft. Right?