Black Box
Black Box
(OP)
Is the 'Black Box' (recorder) found in aircraft independently powered?
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RE: Black Box
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RE: Black Box
RE: Black Box
Current FDRs record over 17 hrs of data on a continuous loop.
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RE: Black Box
There are two "black boxes", actually international orange in color. They are usually located in the aft area of the aircraft for survivability. (Aircraft normally don't back into the earth!)
The flight data recorder records information about the aircraft systems and the cockpit voice recorder records sounds in the cockpit. Both of them typically operate from the aircraft primary electrical AC/DC systems, from electrical busses that are not shed in an emergency. But the black boxes are not typically independently powered. I say typically because while I have a LOT of experience with many airframes, I have not seen them all so I want to be careful not to assume too much.
And as you are probably thinking by now, yes a complete electrical system failure on the aircraft will render the black boxes dead and they stop recording.
IRstuff:
On the very slight chance dik may not know the acronym ULB, allow me to explain. ULB = Underwater Locator Beacon and it is battery powered as IRstuff indicates. If the black box is immersed in water, it activates the ULB to start broadcasting locator signals.
rb1957:
I am not an FAA person, but one question I might raise if I were was how could I insure that the transmitted data could not be altered by someone at the receiving end? The typically scenario for an aircraft crash is someone finds the "black box(es)" and gives them to the on scene FAA/NTSB authorities. The black box(es), or more correctly the data they contain are not reviewed by anyone that is not permitted by that authority.
I completely agree with you that technology allows what you suggest, but the regulatory authorities may not be ready to trust it yet.
And from the other side of the coin, you could say that the data is transmitted directly to an FAA reception point. But how many pilots do you know that would like the FAA to have a permanent record of every single control input and every single sound they made during a flight?
As a final caveat I will note that I am primarily describing transport category aircraft (airline aircraft) and not everything I said above necessarily applies to either military aircraft, business aircraft or general aviation.
RE: Black Box
i was thinking that since most large transport planes have a satcom onboard, the FDR data stream would be small compared with the other traffic.
RE: Black Box
The datalink concept you suggest is being introduced in the 787, nevertheless significant security issues remain as raised by the FAA.
http://
The technology is therefore with us, but as with all such systems, someone is going to have to pay for it; right now there are a lot of cost pressures on carriers from multiple directions.
CVR (voice recording) / FDR (data recording) systems are found installed on smaller aircraft, both rotary and fixed wing, either at customer request, or increasingly through airworthiness authority mandate.
The FDR concept in particular has proved flexible and reliable in recording an increasing number of data parameters as mandated requirements have grown, and is small/light enough to fit in virtually airframe. Airworthiness authorities such as the FAA, EASA etc, do make cost/benefit analyses before making the fitting of new equipment mandatory. I suspect that the case for adopting a data link won't be with us for some time yet.
By the way, the 787 and likely the A350 will feature the newest generation of FDR called the EAFR which features an independent power supply.
http://
RE: Black Box
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RE: Black Box
I was going to ask what a ULB was... slight chance <G>.
Thanks, gentlemen.
Dik
RE: Black Box
Guess where the hackers are going to concentrate their efforts. And given the large number of access points required to make that all happen, guess how often the database will be compromised.
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RE: Black Box
as proof of concept, and to develop the technology, in parallel with an onboard (compliant) black box, broadcast at least some data (why 50Hz for all data ? how rapidly can airspeed change, 1Hz, <10 Hz ?) for some planes.
things weren't done, achieved, by saying "we can't"
RE: Black Box
You bring up some good points. I would like to expand just a bit on one of your points about a redundant, independent power supply. I am not saying it can't be done, but it would be a bit complicated for the flight data recorder, at least on older aircraft. As eng3000 noted above the 787 with a much more modern information transfer architecture may have an independently powered flight data recorder on board.
There are generally two types of data monitored by the flight data recorder. digital bits, and analog waveforms.
Both types of signals require the aircraft electrical systems to be operating (both AC and DC systems) to power the systems and the sensors. In other words, simply maintaining the operation of the flight data recorder would not be enough...all of the systems and sensors that require electrical power would also have to remain operative.
Now for the cockpit voice recorder, you only need to power the recorder itself and the microphone(s) in the cockpit. A redundant, independent power supply here might not be too difficult to implement.
I look forward to seeing the 787 versions of the "black boxes" myself so I can see what has changed.
debodine
RE: Black Box
The explosion of fast and small digital avionics and data collection systems makes all sorts of data collection very possible.
Access to FOQA data cockpit voice recorder and FAA required Flight Data recorder data is heavily controlled and protected by pilot unions. In some cases an Airframe OEM (like Boeing) might really struggle to obtain safety related data from a carrier because of the ALPA agreements with the airline. The flight data recorder is only required to capture a relatively few parameters compared to what is technically possible.
Digital technology has led to some interesting shifts in how accident investigations are handled. For many years the approach has been to avoid criminal prosecution of pilots implicated in accident investigation at all cost. The argument is that pilot cooperation is indispensible for understanding what actually occurs in the cockpit.
That premise is now being challenged as we now can collect sufficient data to know if that errant control input occurred 1ms. before or after the accelerometer signal peaked. That is to say we can collect so much digital data, pilot cooperation is not so indispensible.
In an era where lower time pilots are making their way into cockpits this argument is gaining some momentum. A school bus drive may be filmed constantly as he travels his route every day. As far as I know there is no camera in any commercial cockpit recording the actions of the crew.
RE: Black Box
It would be dangerous if cabin crew had to leave the controls to have their liasons with the cabin crew just for the sake of privacy
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RE: Black Box
The idea is to interrupt the power at the moment of a crash. If the recoders were independently powered, they may survive the crash only to overwrite the interesting data with blank input.
Dan
RE: Black Box
And with a 17-hr recording capacity, a few seconds won't make make much of a dent.
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RE: Black Box
The pilot sent a manual signal at 11 p.m. local time saying he was flying through an area of "CBs" – black, electrically charged cumulonimbus clouds that come with violent winds and lightning. Satellite data has shown that towering thunderheads were sending 160-kilometre-an-hour updraft winds into the jet's flight path at the time.
Ten minutes later, a cascade of problems began: Automatic messages indicate the autopilot had disengaged, a key computer system switched to alternative power and controls needed to keep the plane stable had been damaged. An alarm sounded indicating the deterioration of flight systems.
Three minutes after that, more automatic messages reported the failure of systems to monitor air speed, altitude and direction. Control of the main flight computer and wing spoilers failed as well.
The last automatic message, at 11:14 p.m., signalled loss of cabin pressure and complete electrical failure – catastrophic events in a plane that was likely already plunging toward the ocean.
"This clearly looks like the story of the airplane coming apart," the airline industry official said. "We just don't know why it did, but that is what the investigation will show."
Dik
RE: Black Box
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Dik
RE: Black Box
I suspect that water impact followed by submersion to -28,000 ft [7600M, estimated depths for this area] is beyond design requrements. The FDR & CVR in this mishap may be usless, for data retrieval... even if they can be found. I suspect that the ULB ["pinger" to the rest of us] may also not survive these depths.
Oh yeah. I have a strong suspicion that the US Navy SOSUS system has useful sono data on the mishap... but it may be VERY hard for the US to release classified data cross national boundaries due to the secrect nature of the SOSUS system.... and non-military nature of the incident.
Regards, Wil Taylor
RE: Black Box
re: FDR survivability:
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RE: Black Box
Regards, Wil Taylor
RE: Black Box
Without looking I'd bet there is an FAA Technical Standard Order for data recorders. That document would points to the applicable specs. All the FAA TSOs are listed on the FAA.gov website. Other countries, for ex. Australia and EASA for (Europe) also have TSOs or TSO like documents for the aircraft products they certify.
RE: Black Box
The "how stuff works" article You linked-to on FDR & CVR [CSMU????] ["htt
NOTE: another article I just read stated that the pressure of seat water increased 1-atmosphere roughly every 10-Meters of depth.
So, for a depth of 7600M = ~760-A X 14.7 = 11,172-PSI... far greater that the crush requirement of the boxes [per the article].
The article also goes on to state that the ULB [pinger] must function at depths up-to 14,000-ft for 30-days... about 1/2-the depth possible in the area of the accident.
Regards, Wil Taylor
RE: Black Box
In the Pub thread, we were discussing a redundant FDR that would deploy upon a water landing.
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RE: Black Box
Here's the TSO for flight data recorders.
You probably couldn't sell one to an commercial airframe OEM without a TSO approval.
Likewise, getting an STC for one without TSO would probably be very difficult too.
RE: Black Box
RE: Black Box
The original recorders were tape recorders writing on a steel tape of finite length.
Dan
RE: Black Box
They could have an emergency 'button' or whatever and when it is pressed, all data is streamed to a remote source. Little or no bandwidth required.
I don't think that bandwidth is an issue. They have massive computer systems that are easily capable of handling the amount of data. It can be rendered relatively secure, I would think.
Dik
RE: Black Box
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In the case of wire recordings, the wire was in an infinite loop, while the electronic memories simply recycle on memory addresses.
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RE: Black Box
The CVR was an endless loop, (20 min.?)while the FDR was not. Had to be taken out at regular intervals for a read-out.
This is info from type courses, never having worked on the actual units. Pls correct if I'm wrong.
Dan
RE: Black Box
They are required to pull FDR to verify compliance to requirements, such as the 30-day life of the ULB, and to verify that the memory hasn't gone south. Modern nonvolatile memories have something like 100k R/W cycle limitations, but there are random failures that would be annoying if they happened to be where the last bits of crash data was written to.
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RE: Black Box
From the following report: http://w
Docket No. SA-532
Exhibit No. 12
NATIONAL TRANSPORTATION SAFETY BOARD
WASHINGTON, D.C.
GROUP CHAIRMAN'S FACTUAL REPORT OF INVESTIGATION
COCKPIT VOICE RECORDER
DCA09MA026
(47 Pages)
Page 5
"The CVR had no apparent external damage, other than being wet. The underwater locator beacon (ULB Dukane Model DK100, s/n DM1661, battery expiration date October, 2009) did not function when tested. After shorting the center electrode to the case, no sound was detected using a Dukane Ultrasonic Test Set Model 42A12. The beacon was also tested using a Dukane Test Set Model TS100, which indicated "Open Probe/Batt."
Regards, Wil Taylor
RE: Black Box
A burst of last-minute automatic messages sent by Air France Flight 447 includes one about a problem with a rudder safety device but that does not explain what sent the jet plunging into the Atlantic Ocean, an aviation expert says.
The industry official, who has knowledge of the Air France investigation, told The Associated Press that a transcript of the messages posted on the website EuroCockpit is authentic but inconclusive...
One of the 24 automatic messages sent from the plane minutes before it disappeared points to a problem in the "rudder limiter," a mechanism that limits how far the plane's rudder can move. The nearly intact vertical stabilizer — which includes the rudder — was fished out of the water by Brazilian searchers.
"There is a lot of information, but not many clues," the official said, speaking on condition of anonymity because he is not authorized to discuss the matter.
The official said jets like the Airbus A330 automatically send such maintenance messages about once a minute during a plane's flight. They are used by the ground crew to make repairs once a plane lands...
If the rudder were to move too far while travelling fast, it could shear off and take the vertical stabilizer with it, which some experts theorize may have happened based on the relatively limited damage to the stabilizer.
The industry official, however, said the error message pertaining to the rudder limiter did not indicate it malfunctioned, but rather that it had locked itself in place because of conflicting speed readings.
Investigators have focused on the possibility that external speed monitors — called Pitot tubes — iced over and gave false readings to the plane's computers.
RE: Black Box
http://ww
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RE: Black Box
RE: Black Box
i don't like the theory that the control system force the tail off the plane, though it could have. if the control system failed it could have commanded full deflection (it's supposed to go back to the last "known good" position; why not go back to neutral ??) but deflection is going to be limited by actuator power and at max speed deflections are going to be small. they can still exceed the design parameters, but it seems unlikely to me that the actuator attmts, the rudder structure, the rudder attmts are all stronger than the fin attmts.
i'd've thought that the system might have a structural fuse, like the brkts attaching the actuator to the rudder ... question is is an uncontrolled rudder better or worse than no fin ?
RE: Black Box
That's like telling a new car owner that he should never turn his steering wheel to its limits because that might cause the wheels to fall off.
I'm having trouble grappling with the notion that Airbus would have designed a plane that would fall apart while only marginally exceeding its design operating range.
That's just literally an accident waiting to happen.
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RE: Black Box
the aero boys calculate the rudder force required for the different design cases, and the stress boys (finest chaps) design the structure to handle them. along the line they include failure cases. with everything working normally, everything's "just peachy". it the failure modes that make for interesting work ... the pretty much endless games of "what if". something has to break first, it's a matter of how much thought you put into it ... the guys sizing the actuator brkt may well think "let's never have a failure of the brkt" ... this'd cost the plane <1 lb and normally i'd call this "good excess weight". but the brkt could then be strong enough to allow the system to exceed the design envelop of the rudder ... maybe the rudder broke in two, one 1/2 unrestrained could cause the fin the flutter; i'd like to think that the rudder could handle this failure case.
what would the flight-path be like with the rudder hard over, without a pilot input ?? (sounds like a spiral into the ground, as the inside wing stalls and the outside wing generates a lot of lift).
it me the rudder is possibly a red herring ... if the pitot tubes iced up that'd affect the H. stab (pitch trim), though if the plane was close enough to stall, then the lateral trim would start to get a work-out. but we don't know the details of what they found with the V. Stab
RE: Black Box
I am not an Airbus expert nor am I a flight controls expert so I cannot say for sure how Airbus does this. I cannot even state with certainty what type of relationship is there (linear, non-linear, etc) except I know the relationship between airspeed and available rudder travel is inversely proportional.
The point is since both pitot tubes (and thus airspeed) and the rudder appear to be players in this accident (note I said appear, I am not qualified to second guess the investigating agencies) perhaps the two systems are related in their involvement. Erroneous airspeed information could have allowed larger than desired rudder excursions, and the storm could have provided very large yawing forces that the yaw damper attempted to dampen, possibly exceeding designed-for aerodynamic forces on the vertical tail.
The above is pure speculation on my part of course. But I remember reading about very early KC-135 operations in the USAF where pilots would attempt to manually dampen the natural dutch roll the aircraft had, and if they got behind the aircraft and moved the rudder incorrectly at the wrong moment, supposedly the outboard engine on one of the wings would break away from the aircraft. (Is this urban legend or does someone out there know this to be fact?) I heard it from a retired Lieutenant Colonel for whom I worked years ago.
debodine
RE: Black Box
I think it might be more accurately a case of barreling along in a car at 100 MPH and rotating the steering wheel to one side as fast as possible.
I'm not saying I necessarly agree with Airbus design decisions. The trade press carried some very insightful pilot comments back when the AA crash occured.
I don't think it's really related to the Air France aircraft though.
RE: Black Box
http://www.nytimes.com/2009/06/13/world/13plane.html?scp=3&sq=cascading%20failures&st=cse
Also related to the the significance of the Air Data System and airspeed, in my own experience as a rookie student pilot, I've learned about V sub a = manuvering speed.
This is the speed you must slow to in heavy turbulence to avoid structural damage. At Va the wing stalls (aerodynamically) before heavy turbulence can cause structural damage, but it is fast enough to stay flying.
RE: Black Box
Even at that, you don't expect the wheels to fall off immediately; you might flip the car half a dozen times, but more often than not, the wheels don't come off from the original FUBAR, but from the subsequent impacts with the ground.
Supposedly, it's still possible to steer a plane without a rudder or fin, but it's extremely difficult:
http:
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RE: Black Box
htt
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Regards, Wil Taylor
RE: Black Box
Maybe it doesn't have to be too high tech. Couldn't these things have a slow release fluorescent dye packet built in along with the pinger?
Of course airlines have to absorb equipage costs, governments absorb the investigation costs.
What's an armada of ships equipped with sensitive microphones run now a days?
RE: Black Box
We did discuss the possibility of a deployable FDR, that would float on the surface for just such an occasion.
As for the ultrasonic microphones, it's not just the quantity, but also the depth. The wreckage is ostensibly at the limit of the transmission depth of the ULBs, so you need to have submerged receivers. Additionally, there's no guarantee that the FDRs or the ULBs didn't get so badly damaged from the crash or the subsequent submergence to 4000m depth that they ceased operation. Or, that the wreckage didn't get so buried in silt that the transmission strength was grossly attenuated.
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RE: Black Box
I know older Emergency Locator Beacons were bouy like affairs. I believe we just passed some sort of regulatory deadline to migrate to GPS - satellite ELBs too.
Unfortunately, it may still be strapped to a piece of cockpit bulkhead someplace at the bottom of the ocean.
I kind of wonder how much passenger Personal Electronic Device (PEDs) gear is still actively running that might have an EM signature. Of course with FCC abd CE emissions controls, it would be a small signature too.
RE: Black Box
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RE: Black Box
How about a timed release of something like boyant packing popcorn with embeded RFID chips, possibly designed for easy detection when activated by a radar signal. I read a lot about military ground surveillance radar.
It's well beyond me to visualize the working details, but it seems like it could be made to work. RFID applications seem to extend well beyond the L band.
RE: Black Box
The missing point is that the FDRs already have RF beacons, so if they were on the surface, we would have found them by now. The issue is that the FDRs are usually buried somewhere in the tail for protection, so getting them deployed after a water impact is the primary issue, hence the discussion about a possible redundant FDR specifically for deployment after a water impact.
This FDR would have to be near, or on, the exterior skin of the airplane, and be jettisoned far enough away from the airplane so that it can float clear of the wreckage to reach the surface. The fact that so few bodies have been found, particularly with the hypothesized mid-air breakup of the plane, shows the difficulty in getting something from inside the plane to get clear of the wreckage.
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RE: Black Box
I've seen and installed all of the emergency gear that goes in modern aircraft. I also supported the shops that repaired the gear we're talking about for a couple years. It seems to me that the principle behind some of hasn't really changed much with technology.
Spending millions dollars sweeping the ocean for a pinger, about the size of 2 D-cell batteries seems like an expensive proposition. I guess it has a good track record, but what was the cost to find them?
My first idea was a dye pack. That's probably WWII era thinking. Then I thought about radar detection and floating chaff.
Then I began to wonder what you could intentionally do to a radar return with RFID.
Apparently RFID is inexpensive enough it can be embedded in baggage tags (I saw the prototypes), grocery labels, etc. So I thought maybe they could be embedded in small floating foam objects by the 1000s and placed in various locations within the aircraft structure. Maybe they could be packaged into solid blocks that de-bond or release themselves from within the aircraft structure if the it's cracked open and submerged.
With luck something like this could be developed to require no maintenance beyond keeping it dry.
I'm not involved with radar development, but I am aware that signal processing in modern radars goes far beyond finding something large like a ship or aircraft.
Detection range may be the issue for something like a door prox card. Still it might be possible to develop devices designed to be detected by powerful radar. With the right signature and signal processing maybe a RFID device signal return could be tailored to bloom on a radar screen.
I wrapped up a project to equip a fleet of airplanes with predictive windshear weather radar at my last job. This system essentially detected water droplets moving sideways instead of down. I can only imagine what the military has going on with Synthetic Aperture Radar and ground surveillance. I understood a radar that gave you any sort of decent return from a ground sweep was something of a breakthrough.
To change the subject,
It also amazes me that we've been talking and developing and fielding ADS-B (Automatic Dependent Surveillance – Broadcast ) on 1090 Mhz for ATC (Air Traffic Control) surveillance in major regions across the globe as independent project's for the better part of the last decade. No one I've heard has ever suggested we should be developing a satellite ATC surveillance system that would work over the oceans. The only open water coverage I've heard of involves putting ADS-B receivers on oil rigs.
ADS-B is where the aircraft regularly transmits it's ID, GPS based position, velocity, altitude, heading etc. as a replacement for determining an aircraft's position using ground radar and altitude reporting.
One of the reason we don't know where 447 was or it's speed and direction is because the routine ACARS messages were transmitted about once every 10 min (Aviation Week).
I'm also still not clear why they couldn't avoid the storm front. The airplane certainly had weather radar.
I'm sure it will all unfold as the investigators dig into it.
RE: Black Box
From what I have seen... Airbus needs to consider placing the CVR & FDR... or miniaturized secondary version containing the essence of both [lets-say 30-minutes worth of data for each]... in the middle of the vertical stabilizer.
That-way when the stab fails, and gently flops to the ground or into the water, essential data is easily recovered...
Regards, Wil Taylor
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http:/
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