Door Boeing 737 pre-MAX opens after takeoff, aircraft returns in safety | Hacker News Reader

Door Boeing 737 pre-MAX opens after takeoff, aircraft returns in safety

luchtvaartnieuws.nl

43 pointsj-a-a-p22 comments

Key bit from the article translated:

There is no connection to recent problem with the 737 MAX 9 where a door plug was not installed correctly. Instead, this occurred on an older (previous generation) 737 airplane. The cause of this incident is that the door had not been closed properly prior to take-off.

(original Dutch: "Er is geen enkel verband met de deurplugproblematiek van de 737 MAX 9: het gaat in dit geval om een 737 van de vorige generatie, waarbij de deur voor vertrek niet goed luchtdicht was afgesloten.")

They say that, but the doors are closed, cross checked and then the pilots would be alerted by a sensor if a door is open.

So did three or four members of staff get this simple thing wrong or is the plane at fault?

Are the door sensors redundant on the 737, or do the crew and pilot just check different readouts of the same?

One flight attendant physically closes and arms the door, so it is in automatic mode such that the slide will deploy if its opened, then a separate flight attendant physically checks that it is closed and armed. I have no information the sensor redundancy, but the physical checks are redundant.

How can a plane take off if the door isn't properly closed? How isn't there a detector, and a mechanism that just prevent the plane to even move if the door isn't closed. That's what trains do (and the earlier iteration of this design in train is decades old and really basic: on old trains there's a wire running through all doors which are acting as switches mounted in serial: if one is open, there's no current)

On trains, "stop" is generally a safe action. On planes in the air, "stop" is a deadly action.

As described, that sounds like a mechanism that could potentially go very wrong on a plane. By way of example, consider if the plane was in flight and a door opened: the pilots need full control of the plane in order to land it.

There should absolutely be mechanisms to detect and avoid this situation, but hard interlocks like you're describing could cause catastrophic failures in flight.

> On trains, "stop" is generally a safe action. On planes in the air, "stop" is a deadly action.

Having worked in this industry (edit: train industry) I'm fully aware of that.

> By way of example, consider if the plane was in flight and a door opened the pilots need full control of the plane in order to land it.

Not necessarily. Or at least it depends how you define “full control”: of course everything related to flight is mandatory. But, for instance, the ability to unlock the parking brakes of the landing gear likely isn't something you need while piloting mid-air and this is enough to implement the safety mechanism I talked about.

Also, you could have a bypass for the safety lock in case something goes wrong. For instance in PWR nuclear reactors, you don't want to accidentally overflow the steam generator, so there's one pump, designed to feed it when the reactor is stopped, that is disabled when the reactor is running. But in case of accident you may actually need this pump, so there's a key (literally a physical key) that you can use to disable the protection and make the pump usable in that mode too.

In flight maybe not, but after flight there comes landing, and landing on wheels that have parking brake engaged (because of that interlock) may or may not be safe. Yeah, you can add logic to prevent that, you can add more manual overrides, but eventually there's a point when new feature (even one added "for safety") will cause more problems that it will solve.

That's true that there's a balance between the safety benefit you get from the feature and the overhead it ads for the operators (the key example in nuclear reactor I was talking about has actually caused a issue once leading to the enforcement not an additional procedure around it).

What I meant in my response is that the answer cannot simply be “interlocking in a plane would be too dangerous”, so my original question still stands: why is it the case in airplanes when it looks so fucked up from a train perspective.

> Also, you could have a bypass for the safety lock in case something goes wrong. [...] there's a key (literally a physical key) that you can use to disable the protection

I'm entirely in favor of having a safety mechanism with explicit warnings and a bypass mechanism, with that bypass mechanism being something that should never happen in normal operation.

I was solely arguing against the kind of interlock that a train has where "current can't flow" if the doors are open, since the plane should absolutely be able to operate with the doors open in order to safely land.

I understand what you mean. Just to clarify, when I said current couldn't flow it's obviously some dedicated very low voltage current that is merely supposed to act a sensing mechanism, it's the not actual current powering the train that is being cut hard by the doors.

This response is incredibly dramaphobic. I want to hear more anti-Boeing screeds.

Only going from the translation, this seems more likely to be a maintenance issue or crew error than another shocking quality problem, since I believe the 737-800 and -700s that they fly haven't been manufactured since at latest 2020, and their average age of their (Transavia's) 737 fleet is 13 years.

As disappointing as it was watching the recent Wendover video breaking down the Boeing decline, this is probably not part of the story.

Seems Boeing just can't catch a break lately.

I'm somewhat surprised that there isn't a warning in the cockpit for a poorly closed door on an airplane. My car warns me of that! (Granted, my car door isn't necessarily airtight, but still)

> I'm somewhat surprised that there isn't a warning in the cockpit for a poorly closed door on an airplane.

There are multiple. In the 737NG, for example, you'd expect the "master caution" light to come on, an audible chime, and an indicator "DOORS"

You can see this yourself in the flight crew operations manual: https://www.pilot18.com/wp-content/uploads/2017/01/B-737-7-8...

see page 15.10.1. (pdf page 1793)

The details on the meaning of this light are on page 15.20.4 (pdf page 1812)

That’s interesting. In the article it says:

> According to De Telegraaf, no signal would have come through in the cockpit before departure that the door was not closed properly.

That obviously makes no sense. My car will tell me if a door is open, but somehow there is no sensor to detect this on a plane, where such a thing would be catastrophic as the plane gained altitude.

they are wrong. see edited and expanded parent post

Interesting! I guess that leaves 2 possibilities. Either the pilots ignored/missed the warnings(seems unlikely), or the warning system was somehow faulty(seems more likely, given Boeings recent track record)

> There is no connection whatsoever with the door plug problem of the 737 MAX 9: in this case it concerns a 737 of the previous generation, where the door was not properly closed airtight before departure.

(Machine translated from the linked article)

This is such a weird way to write this: Bij het opstijgen van een Transavia-vlucht is vorige maand een deur van het toestel een beetje opengegaan

Duing ascent of the Transavia flight, the door of the airplane opened a little bit (emphasis mine).

What the hell, how does the door on your airplane open ‘a little bit’?

Ah, here we go again :-D

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