Bounced a couple of times & burst into flames

[FG Lurker]

Well a fly-by-wire aircraft doesn't have a hydraulic system as such.

From your quote, "The actuators are usually hydraulic, but electric actuators have been used."

Fly by wire doesn't remove the need for a hydraulic system to do the actual work, it just controls that system through a computer instead of directly from control stick inputs.

In the case of electric actuators there still needs to be control and power wiring in place to, well, control and power the actuators. I don't have Tsuru's detailed knowledge but I assume that a seriously catastrophic engine "failure" (ie the engine getting ripped from the wing) could damage wiring in much the same way it could damage hydraulics.

[Mock Cockpit]

From your quote, "The actuators are usually hydraulic, but electric actuators have been used."

Fly by wire doesn't remove the need for a hydraulic system to do the actual work, it just controls that system through a computer instead of directly from control stick inputs.

In the case of electric actuators there still needs to be control and power wiring in place to, well, control and power the actuators. I don't have Tsuru's detailed knowledge but I assume that a seriously catastrophic engine "failure" (ie the engine getting ripped from the wing) could damage wiring in much the same way it could damage hydraulics.

I'd assume that each of the actuators are separate systems with multiple redundancy. TSURU!!! Help.
Modern aircraft are designed so that an engine separating from the wing goes down and away. In theory anyway.

[FG Lurker]

I'd assume that each of the actuators are separate systems with multiple redundancy. TSURU!!! Help.

I assume that all flight-critical systems on a modern airliner are built this way -- I certainly hope so, anyway. It still doesn't make said systems immune to bad maintenance or a big enough failure. Flying is incredibly safe but it's not impossible to crash.

[Mock Cockpit]

I assume that all flight-critical systems on a modern airliner are built this way -- I certainly hope so, anyway. It still doesn't make said systems immune to bad maintenance or a big enough failure. Flying is incredibly safe but it's not impossible to crash.

I still can't understand how they get 200 tons of metal with a million separate bits into the sky but they can't get the in-seat video to work properly.

[IkemenTommy]

This may be the dumbest question yet to be asked but are carrier planes required to carry the same black box recorders like the passengers do? No one has seemed to touch this so I am assuming they aren't required. Can someone answer this?

[FG Lurker]

This may be the dumbest question yet to be asked but are carrier planes required to carry the same black box recorders like the passengers do? No one has seemed to touch this so I am assuming they aren't required. Can someone answer this?

Some news stories have reported that the both the data recorder and the cockpit voice recorder (aka the black boxes) have been recovered from the FedEx plane and that the data appears to be usable.

[Tsuru]

From your quote, "The actuators are usually hydraulic, but electric actuators have been used."

Fly by wire doesn't remove the need for a hydraulic system to do the actual work, it just controls that system through a computer instead of directly from control stick inputs.

In the case of electric actuators there still needs to be control and power wiring in place to, well, control and power the actuators. I don't have Tsuru's detailed knowledge but I assume that a seriously catastrophic engine "failure" (ie the engine getting ripped from the wing) could damage wiring in much the same way it could damage hydraulics.

Electric actuators do exist and have found many uses in aircraft, but they are to my knowledge not currently used in primary flight control systems, as hydraulics are simply better suited to do the job. They are usually used as a backup to move secondary flight controls such as the horizontal stabilizer trim or the flaps in case of a hydraulic pressure loss or other failure, but even the most state-of-the-art FBW B777 or A380 still uses pressurized hydraulic fluid to power the main controls. The only difference in fly-by-wire is that instead of cables and pulleys connecting the pilot's controls to the control valves driving the actuators there is a computer that drives the control valves instead.

That's not to say they will not be here in the future.... I think the 787 will have them.

I'd assume that each of the actuators are separate systems with multiple redundancy. TSURU!!! Help.
Modern aircraft are designed so that an engine separating from the wing goes down and away. In theory anyway.

In all big airliners there are multiple redundant hydraulic systems, and the primary flight controls have their different surfaces divided up between them so that in case of a single or multiple hydraulic pressure loss, when at least one system remains pressurized all three main control movements are still possible. The problem with the Chicago DC-10 is that the engine separation also tore out the valves controlling the slats on the left wing and with it the fuses which are there to prevent the slats from retracting when hydraulic pressure is lost in that particular system and the slats happen to be extended at that time, by trapping the fluid. In this case, the fluid just departed from the actuators through the open door and in they went.

With regards to underslung engine separations there are a lot of different factors in play here, but most airliner jet engines as it turns out will in fact separate upwards and to the right, in part due to the gyroscopic precession of the equivalent of a family car spinning at 12000rpm at full blow, and because of the fact that in both the Amsterdam, Chicago engine separations and loads of other cases, the rear engine mount is the one where the initial failure occurred, with the remaining front mount giving the engine with all of its thrust a natural hinge upwards and over the top of the wing.

This may be the dumbest question yet to be asked but are carrier planes required to carry the same black box recorders like the passengers do? No one has seemed to touch this so I am assuming they aren't required. Can someone answer this?

As I recall, all aircraft over 5.700kg are required by law to carry flight data recorders these days, regardless of what they carry.

[Greji]

As I recall, all aircraft over 5.700kg are required by law to carry flight data recorders these days, regardless of what they carry.

Right on top as usual Tsuru. You need to get up there! You got your ticket yet?

[Tsuru]

Right, so I flew the KLM MD-11 sim this afternoon and I spent a considerable amount of time shooting manual approaches in comparable weather conditions to the Narita accident (20 knots crosswind gusting to 32 as reported at the time, with a bit of low-level turbulence put in for good measure), and I have to say even at max landing weight (~190 tons, way more than these guys were) it was piss easy as long as you didn't encounter wind shear. With these winds still in I even took it to Kai Tak and flew perfect curved approaches four times in a row, and made landings that could put some real pilots to shame. Even landing in the max demonstrated crosswind and even over it is comparatively easy with the MD as long as the airmass is relatively stable. Just as long as you don't get into a sharp windshear when you're below 100 feet like these guys.

That said, even at 190 tons it does like to lift up the upwind wing when going around for the next approach, and yes, it's quite a handfull at times, likes to bounce on touchdown and is not as nice to fly as its Boeing counterpart, the fly-by-wire 777-200ER I flew before it was time for my slot on the MD-11 machine, but I don't think the plane in itself is a widowmaker of any sort. Hell, even I could make good max crosswind landings in it with no prior experience on type!

So yeah, I'm certain these guys had their pants brought down by a sharp windshear at a very low altitude in the approach and it made them screw up their landing badly. After spending all of this time trying to crash it myself, it it's difficult to conceive how this could not have been the case.

[Tsuru]

Crappy cellphone pic from when I was waiting for the sim's motion platform to shut down and the bridge to lower so I could get a coffee, the plane is sitting at the gate at Kai Tak with AC ground power on, and with engines and IRUs shut down, you can see the automated marshalling guidance system out the window. Apologies for not having any in-flight pics to share as I was the only one on board.

[Greji]

Crappy cellphone pic from when I was waiting for the sim's motion platform to shut down and the bridge to lower so I could get a coffee

That was right before you ran over the follow-me truck and taxi'd into the terminal building, right?

[pheyton]

Could a microburst have been at play here?
http://en.wikipedia.org/wiki/Microburst
Saw a story on these years ago and after seeing that FedEx plane bounce like that it came to mind. It came to mind after asking my wife if she had sent any packages to Japan that week....

[Tsuru]

I think the FDR data will have to tell us the complete story, but it is a possibility. Technically a microburst is a very specific kind of wind shear, as wind shear just refers to a sudden shift of wind direction and/or speed relative to the aircraft.

The most famous example of a crash due to a microburst in the approach phase is that of Delta 191 at DFW in 1985. One thing you see when entering a microburst is an increase in airspeed and decrease in groundspeed at the same time, and combined with the use of an autothrottle system which strives to keep the aircraft at the same airspeed this will lead to a decrease the energy in the aircraft to a level that a full on stall will occur when entering the second phase of a microburst, as the airmass reverses direction almost instantaneously removing a big chunk of airspeed in seconds. The airplane now finds itself in a situation where both airspeed and groundspeed are extremely low, and full power is usually required to power out of it and prevent striking the ground as the Delta Tristar did. The exact winds the Tristar encountered that day are included in the adverse weather package delivered with every simulator made these days, to train new crews for this phenomenon.

Judging from the video of the FedEx crash I don't think this was the case, as the speed of the aircraft actually looked to be too high over the fence rather than too low, and the bounce on landing is a typical result of this.

Delta 191 FDR analysis and simulation in what looks to be a 767 or 757 sim:

[yt]giTxW4EVOMM[/yt]