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Comment by SteveVeilStream | Hacker News Reader

One possible scenario is that they had a bird strike on one engine but then accidently turned the working engine off instead. Full loss of power from both engines could have taken the data recorder offline in an older aircraft like this one. With both engines off, they may have panicked to try to complete a tight turn to return to the airport and to maintain altitude to make it to the runway. It's possible the landing gear was forgotten but also possible that it was intentional (to extend glide.) It's too early to know anything with certainty but I suspect that the investigation will show that a different set of choices would have allowed them to put the plane down safely (for example by continuing with the initial approach.) Even in that case, they may not have been to blame - for example they may have been following a standard procedure that should be revisited.

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I was under the impression that these CDR/FDRs were independently powered. But a quick Quack on DuckDuckGo didn't answer anything.

That two different recorders both went titsup at the same time I find mind boggling and very sus.

edit: apparently they have both AC and a battery backup, if the internet is to be believed.

Which makes a simultaneous loss of two devices with battery backups... curious.

Did they get hit with an EMP?

If the motor was just shutdown, it should still make power off windmilling. If they discharged the extinguishers, then there is no more power. In any case, that should be recorded.

Battery backup was not required until 2010. This aircraft was manufactured in 2009. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G...

The general populace seems convinced that black box recorders are made of adamantium and can return data even if the plane falls into a black hole.

Meanwhile every time I read about a crash, I'm horrified by how primitive the requirements (and implementation) appear to be.

This reminds me of my favourite method for reviewing software I had never heard of: I check the release notes. If version v17 has "now uses transactions" then that means that the developers were happy to release the first sixteen major versions with data corruption as a feature. (Conversely, if the notes only mention fantastically obscure scenarios being fixed, then the basic issues have been fixed long ago.)

Battery backup being introduced in 2010 as a requirement is absolutely insane. It's not like batteries or battery backup are new technologies! This stuff has been around forever. Why on earth was this not a requirement decades ago!?

I find it just as crazy that many or most personal cars come equipped with cameras and sensors all over, but are not required to record any of it for analysis of a collision and attribution of fault.

The most unqualified person can be driving a 10,000 pound (4,500kg) electric Hummer and have no measures in place to use the built in cameras and sensors to determine what went wrong in the event of a collision.

Hell, there are cameras inside the vehicle that can tell us whether or not a driver was using their phone when a crash happens, but it does not seem politically popular to enforce reviewing this footage, even though being in a personal car is far more dangerous than being a passenger on a plane.

This is not strictly true and most cars have black box modules which record control inputs and IMU data.

I have never heard of this used to determine who is at fault in a collision. Does that happen? Also, video would be a tremendous help for ascribing proper blame, so why wouldn’t that be required?

When airbags came out, video recording was expensive, but that has long not been the case.

It does happen! These devices are generally only installed post-2005ish cars and the data is used more for safety investigations (did this car have a hardware fault) than insurance, simply because it takes a decent amount of skill to construct a narrative off those devices.

Video isn't required because even these black boxes, AFAIK, are STILL not required in the US. They also introduce unacceptable privacy compromises for Americans, seeing as how most people subconsciously treat their car as an extension of their living room.

>Video isn't required because even these black boxes, AFAIK, are STILL not required in the US. They also introduce unacceptable privacy compromises for Americans, seeing as how most people subconsciously treat their car as an extension of their living room.

…that is my point. For the most dangerous activity people in the country do, we avoid laws that would help ascribe blame because everyone wants to be able to break the rules. A pilot gets recorded, regardless of their privacy, because they are responsible for other people’s lives.

Why not drivers? They certainly cause damage to other people. And at a rate far higher than a person doing ANY other activity. It’s not about privacy, it is about wanting to avoid accountability.

The airbag module does record acceleration, seat belt status and the general scenario used to deploy the airbags/tighten the seat belts.

The car situation is at the unholy nexus of bad behavior, money, and privacy. My insurance company would dearly love to have access to the existing telemetry in my vehicle. As an alternative, they continually beg me to install a telemetry device in the OBD port in exchange for lower premiums. But their incentive is so obviously to use the data against me in the event of a claim ("ohho! 31 in a 30 zone! Denied!") that I see no reason to do so.

Dashcams, by contrast, provide the operator with reasonable evidence of other drivers' behavior, and consequently are popular - people pay out of pocket to install them.

I suspect that if laws were passed requiring use of telemetry and dashcams all over, all that would really happen is that rates would rise to reflect new data on how badly most of us drive, and claim denials would skyrocket.

be certain it does at the moment of claim denial. parallel construction for the win

> As an alternative, they continually beg me to install a telemetry device in the OBD port in exchange for lower premiums. But their incentive is so obviously to use the data against me in the event of a claim ("ohho! 31 in a 30 zone! Denied!") that I see no reason to do so.

So your incentive is to pay less money, and their incentive is to pay less money. They figured out a way to do that and still be in business. Obviously, some people might value driving over the speed limit more than the lower premium.

> I suspect that if laws were passed requiring use of telemetry and dashcams all over, all that would really happen is that rates would rise to reflect new data on how badly most of us drive, and claim denials would skyrocket.

You don’t think people would change their behavior if their actions were likelier to result in consequences to their bank account and/or prison time?

Almost everyone is distracted driving to the point that personal motor vehicles are, by far, the leading morbidity and mortality risk for people, especially children.

We go scorched earth when kids are kidnapped or otherwise at risk, but for personal cars, we explicitly look the other way when we have a way to make kids safer.

Quite the double standard people have when they want to break the rules themselves.

It may be relevant that the dash cam is owned by the driver and not the insurance company, and can be selectively used to prove others' fault, but ahem forgotten about if it shows otherwise.

Because adding a battery backup means one (or two!) more batteries that have to be tested and certified to fly; more batteries that have to be checked before flight; more points of failure that could ground an aircraft or cause incidents themselves; more weight on board (especially relevant for smaller craft); etc. etc.

The battery issue isn’t idle speculation; a recent flight I was scheduled for was cancelled when the airline accidentally allowed a battery to deep discharge, necessitating a new battery to be flown in from another city (delaying the flight so badly it was cancelled instead and passengers delayed to the next day).

Fascinating. How did you find out?

They announced the details at the gate. They even told us they were trying to get a new battery in from Cleveland (we were in Pittsburgh). I didn’t find out which battery was discharged though.

I hope that’s a trend. My experience has always been that they give zero information about such circumstances.

> Battery backup being introduced in 2010 as a requirement is absolutely insane

I welcome the formation of your company selling already-certified batteries that will not damage anything around them (like the precious recorded data) if they go from 500 to 0 in no seconds flat, are subjected to pressures of a few kilometers of water, or to a post-crash fire.

The batteries do not have to be located close to the recorded data

Then wires break or get burned. Causing cuts like now.

Did some airplanes have battery backup before that?

It's my recollection of several crashes, where the plane is not immediately recoverable that there is always a concern that the black boxes will overwrite themselves.

There's a slew of models and different methods for recording.

The time period they record tends to be very short, but that does raise an interesting question, when do they stop recording?

Even if the FDR is powered, if the flight computers/systems are without power there is nothing to record.

Note that just shutting down normally the engine would not cause a power loss. Only in the case of a turn off with extinguisher. Of course after bird strike you shut it down with extinguisher.

Now there is clear procedure, with checks that has to be memorized, where you first identify the engine. Pilots are regularly tested for that procesures. Why it went wrong?

I remember that Boeing changed which pack provides air conditioning to the cockpit between the 737-200 and the 737-300, which lead to a few similar situations in which pilot were confidently wrong which engine was bad based on smell alone.

It was changed in 737-400. Before it only took air from the right engine, but 737-400 took from both. In the Kegworth air disaster, which was caused by a failed blade and the system causing a fire trying to compensate by injection of more fuel, the pilot assumed the fire was in right engine and turned it off as crew never notified them which engine was burning. When they discovered the error the speed was too low to kickstart the engine.

https://en.wikipedia.org/wiki/Kegworth_air_disaster

You would think that such a complicated machine would have some better method to notify pilot which engine failed, instead of "does it smell like right or left engine".

There are a series of gauges associated with each engine, but in a high workload situation it might take some effort to make sense of them.

I assumed it was the 300 because that was the big overhaul with a new marketing name, and the 400 is often only described as a stretched 300.

I can't actually find a single source on which one it was.

It could also be a flock of birds damaging all the engines.

Does the APU automatically start or is it a manual process?

Manual process.

Batteries are there for at least 30 minutes

Not required for planes manufactured before 2010. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G...

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