[eric4smith]

I sympathize with the engineers there.

It's like a bug that will not go away in some software. You think you've fixed it and all seems well and you get a good nights sleep with the gleam of satisfaction in your eyes.

But the next day your manager says "That bug is still there".

You incredulously do not believe that bug report and go to replicate it yourself.

And surely, under some edge weird case scenario, it really happened.

You put the fix in and uneasily sleep the next night. You actually dreamed about the issue. And wake the morning with no reports.

Over the next weeks and months, its all good. No new reports. and your mind has turned to some new projects. Surely that bug has been squashed.

And then one day...

I feel their pain. It's not the same, because lives and reputations are at stake. It's so much worse.But I feel their pain.

[na85]

Aerospace engineer here.

From TFA:

>A component of the main electric trim system became inoperative. Our pilots ran the appropriate checklist, which included manually trimming the aircraft. They returned to MIA and landed uneventfully. The issue was not related to MCAS.

That statement is from the airline, not from Boeing, so I'm more inclined to trust it. Additionally, if the airline lies and it turns up on an airworthiness audit (air maintenance organizations are subject to regular audits) then the penalties are quite severe.

In any case, per the airline's statement it was an issue unrelated to MCAS. Aircraft break literally every day in a myriad of ways that are often invisible/imperceptible to people riding on that very aircraft. In this particular case it was some unspecified component of the electric trim system.

You can look up the Master Minimum Equipment List for the B737[0] and see for yourself just how granular the approved maintenance program gets for aircraft like this. Everything on the MMEL is essentially an item that can be broken and the aircraft can still take off legally. Note that this is a different (and more rigorous) standard than "can be broken and aircraft can take off/operate safely".

I don't know exactly what broke here but I suspect it is a part that has broken on 737s hundreds if not thousands of times in the past, with similar outcomes.

I merely dabble in software but to further your analogy: This situation is when you've been dreaming about that bug for weeks and you get the call from the boss thinking it has recurred but instead it turns out it was a similar-smelling failure caused by some intern's microservice not failing gracefully when confronted with a network outage that brought down the system anyways.

[0] https://fsims.faa.gov/wdocs/mmel/b-737%20r55a.htm

[danaliv]

Flight instructor here. This person knows what they're talking about.

[worker767424]

But this doesn't feed the machine that is the 24-hour news cycle. I fully expect cable news to try to declare "more trouble for troubled plane," even though it appears to be a garden variety failure.

[weego]

I think that attempts to whitewash the fact that Boeing have managed to burn the trust it spent decades building on the space of 2 or 3 years. This is the natural outcome -- until time proves otherwise again, every failure will be under a lens

[corndoge]

> until time proves otherwise again, every failure will be under a lens

But it's really not every failure. There were 2 other failures on Boeing airliners yesterday alone and nobody posted the other two.

American B38M near Nassau on Mar 29th 2021, pitch trim issue/failure (OP's article)

Southwest B737 at Denver on Mar 30th 2021, speedbrake arming issue

United B739 at Denver on Mar 30th 2021, flaps problem

Day before

Batik B739 at Semarang on Mar 28th 2021, hydraulic fault

Aeroflot B738 at Krasnodar on Mar 28th 2021, flaps problems

Day before that

ANA B773 over Pacific on Mar 28th 2021, engine shut down in flight

iAero B734 near Evansville on Mar 27th 2021, loss of cabin pressure

Here's a 737-800 with a similar electrical trim issue recently https://www.youtube.com/watch?v=nLonztIXXWQ You probably didn't hear about that one

Like others said these aircraft fail every single day. People who read about them don't post them on HN because they're so common.

[timw4mail]

Not to mention that the 737 series of planes is the most produced passenger plane in history.

The odds of none of them having issues on a given day is slim.

[mypalmike]

These common imperceptible failures... Do they involve the aircraft turning around and flying an hour back to the departure airport?

[tallanvor]

Yes, if the destination isn't a maintenance base that stocks the part that fails. It's happened to me - 45 minutes into a 1 hour flight they decided to turn around and return to our departure airport. It's very annoying.

The problem is that some failures mean the plan can't fly again until the part is replaced, and sometimes it's cheaper to turn around than to have the plan sit idle until they can get the replacement part out to it along with someone certified to repair it.

[slacktide]

Yes, they do. I suggest that you set avherald.com as your homepage for a week, and learn how common air turnbacks and diversions are.

[qwertox]

Fun comment section on that site

> This girl is one of a few 757s that Delta uses exclusively for charters. Lower cycles on them. 31.5 years old and still chopping up birds. Love it. Long live the 757!!

http://avherald.com/h?article=4e52aeea&opt=0

[conistonwater]

One "silly" reason why minor failures result in flying back to the original airport is sometimes that the original airport is some sort of hub for the airline with plenty of equipment and personnel for maintenance, which makes it cheaper for the airline to repair the plane specifically there compared to another airport. If you follow avherald.com even a little bit, you will notice a lot of incidents result in exactly that.

[na85]

That would strain the definition of "imperceptible", wouldn't it?

My point is that aircraft break all the time. Once in a while they break in such a way that they need to return to base. This wasn't an MCAS failure.

[mypalmike]

Your wording was problematic. "In this case" strongly implied you were putting this incident in the same category.

[na85]

Perhaps my wording was careless; I can't go back and edit it now.

[ironmagma]

The fact it wasn’t MCAS really isn’t important. What is important is that Boeing has completely botched the development of this aircraft and this continues to be revealed to us in new ways over and over again. It’s a management issue through and through.

[BillyTheKing]

the good old programming testing rule: the number of bugs you will find in a piece of software is proportional to the number of bugs you already found

[eric4smith]

Lol so true.

[igravious]

FTA: "The issue was not related to MCAS"

[trynton]

It's not the engineers pain, as it wasn't an engineering decision to mount the engines higher and forward of the wing. Precipiting a pronounced nose-up aspect. All the same, I admire your attempt to deflect blame from the management at boeing.

[ramblerman]

> I admire your attempt to deflect blame from the management at boeing.

Bah, what a vile comment. He didn't contest that at all.

It's the engineers who will have to go through this exercise of fixing it, and he identified something most of us can probably relate to.

[koonsolo]

It's definitely the engineers pain. It's clear that management is the cause of all this shit, but the problem now lies in the engineers lap. So who has to solve it? Right, the engineers.

[sofixa]

They're the ones that accepted and designed an unsafe aircraft ( a single sensor known for failure feeding a critical system that can crash an airplane? And they hid it from the FAA? They absolutely knew what they were doing and should rot in jail for at least a few years).