5 ms·

I can understand needing to have that option for most things, but a blackbox flight recorder ought to, by it's basic design, be read-only and have little to no

by ozr 3y ago

I can understand needing to have that option for most things, but a blackbox flight recorder ought to, by it's basic design, be read-only and have little to no dependencies with the rest of the aircraft. E.g.: a failed APU should not disable the blackbox, since you want to be able to record that the APU failed.

SoftTalker 3y ago
Yeah I'm sort of speculating and agree for the most part but obviously the data recorder is communicating with every other system on the aircraft for which it records data. If the data recorder had some kind of fault that was creating interference with these systems, maybe there's a scenario where you have to be able to shut it down. If I'm thousands of feet above the ground and the system keeping me in the air has some kind of fault, when I say "Hal, shut down that faulty system" I don't wan't the answer to be "I'm sorry Dave, I cannot do that."
refurb 3y ago
Electrical wiring fault starts a fire. Not sure we don’t want a pilot to be able to pull circuit breakers for everything on board.
antonjs 3y ago
You could always have some breakers that could only be pulled by the chief flight attendant, or at least signal to someone in the cabin they were being pulled.
- samtho 3y ago
  > You could always have some breakers that could only be pulled by the chief flight attendant This would be a very bad idea. Deadly aircraft incidents, while exceedingly rare given the number of flight hours that happen every day, often happen within seconds. If there is something that is causing an issue that requires communication to someone (who is likely doing something else) outside of the cockpit, you may not get to it in time. Safety of the passengers and crew is the number one priority, and the captain should not have anything forbidden from his or her usage.
samtho 3y ago
First off, there are two recorders: the cockpit voice recorder and the flight data recorded. The voice recorder needs power which is provide by the aircraft and is a rolling 2-hour recording. If there is an incident, the captain will pull the breaker to this system to prevent the recording from being overwritten after on the ground, or, in the worst case, aircraft destruction will cause the severance of power to the device for a similar effect. The flight data recorder a very dependent on all the systems of the aircraft, it listens on all electrical buses, senses the position of controls, and records datapoints at a defined rate for a rolling two hours of flight time. It has a small battery system to capture what it can, but if you lose engine generation and your APU, you either gliding to a crash landing in the best case or you are just hosed and it will be literally seconds before you’ve reached the ground. Both of these things are not read only, they continually rewrite their memory because it’s usually the last bit of flight data that matters. There are pushes to make a system that can allow for 18-20 hours of flight data, but everything moves slowly in avionics.
- ozr 3y ago
  To be clear, I meant read-only in the sense that a fault in in either recorder should not be capable of interfering with the rest of the plane.
  - HWR_14 3y ago
    Something physically attached (especially to the electrical system) can always theoretically interfere with the rest of the plane. If there is a fire, is the pilot just supposed to shrug as the plane goes up because he cannot interfere with the black box?
    - dale_glass 3y ago
      Optical isolators exist exactly for this purpose. They're common, cheap, only work in one direction and result in no electrical connections between both sides.
- GeorgeTirebiter 3y ago

by ozr 3y ago

SoftTalker 3y ago

Yeah I'm sort of speculating and agree for the most part but obviously the data recorder is communicating with every other system on the aircraft for which it records data. If the data recorder had some kind of fault that was creating interference with these systems, maybe there's a scenario where you have to be able to shut it down. If I'm thousands of feet above the ground and the system keeping me in the air has some kind of fault, when I say "Hal, shut down that faulty system" I don't wan't the answer to be "I'm sorry Dave, I cannot do that."

refurb 3y ago

Electrical wiring fault starts a fire. Not sure we don’t want a pilot to be able to pull circuit breakers for everything on board.

antonjs 3y ago

You could always have some breakers that could only be pulled by the chief flight attendant, or at least signal to someone in the cabin they were being pulled.

samtho 3y ago
> You could always have some breakers that could only be pulled by the chief flight attendant This would be a very bad idea. Deadly aircraft incidents, while exceedingly rare given the number of flight hours that happen every day, often happen within seconds. If there is something that is causing an issue that requires communication to someone (who is likely doing something else) outside of the cockpit, you may not get to it in time. Safety of the passengers and crew is the number one priority, and the captain should not have anything forbidden from his or her usage.

samtho 3y ago

First off, there are two recorders: the cockpit voice recorder and the flight data recorded. The voice recorder needs power which is provide by the aircraft and is a rolling 2-hour recording. If there is an incident, the captain will pull the breaker to this system to prevent the recording from being overwritten after on the ground, or, in the worst case, aircraft destruction will cause the severance of power to the device for a similar effect. The flight data recorder a very dependent on all the systems of the aircraft, it listens on all electrical buses, senses the position of controls, and records datapoints at a defined rate for a rolling two hours of flight time. It has a small battery system to capture what it can, but if you lose engine generation and your APU, you either gliding to a crash landing in the best case or you are just hosed and it will be literally seconds before you’ve reached the ground. Both of these things are not read only, they continually rewrite their memory because it’s usually the last bit of flight data that matters. There are pushes to make a system that can allow for 18-20 hours of flight data, but everything moves slowly in avionics.

ozr 3y ago
To be clear, I meant read-only in the sense that a fault in in either recorder should not be capable of interfering with the rest of the plane.
- HWR_14 3y ago
  Something physically attached (especially to the electrical system) can always theoretically interfere with the rest of the plane. If there is a fire, is the pilot just supposed to shrug as the plane goes up because he cannot interfere with the black box?
  - dale_glass 3y ago
    Optical isolators exist exactly for this purpose. They're common, cheap, only work in one direction and result in no electrical connections between both sides.
GeorgeTirebiter 3y ago