Afriqiyah Airbus 330 Crash
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Not forgetting, of course, that in a sim, the disorientating illusion of being tilted back during a real g/a is created by - tilting you back....................
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CONF iture, I don't think the initial GPWS is a consequence of the Go Around, as we can read that the TOGA selection was a RESPONSE to the first GPWS warning at 1000ft.
So I would say first GPWS due to unstabilised approach and high (very) rate of descend (at least 2500 ft/min to get the Warning according to FCOM 1),
and then TOGA selection and mess up with the pitch and/or flaps/gear/crm...
So I would say first GPWS due to unstabilised approach and high (very) rate of descend (at least 2500 ft/min to get the Warning according to FCOM 1),
and then TOGA selection and mess up with the pitch and/or flaps/gear/crm...
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Synopsis of expert opinion here?
Scenario is - PF subjected to somatogravic illusion, caused by entering foggy/cloudy conditions at dawn, while attempting to relalign a bad approach and so under significant thrust. Pitched it foward, came out of the fog pointed down, tried to GA and couldn't get altitude in time. I'm still mystified that the fuselage was completely fragmented while the wings ended up intact and far away, but I guess if it hit just right the wings might actually bounce as a unit and keep flying.
-drl
-drl
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Think we said enough. Basic flying error. I see it daily in the sim. No need to look for special things. Been around the world. Not surprised. Hope I will be proven wrong..
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Next question for Bus drivers: What kind of thrust does the A/T command after hitting the TOGA buttons on a go-around? My experience is limited to only the 76/74 (2000ft/m climb) and the MD11 (full thrust).
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Max thrust 76-er, sky is the limit.
AEC,
We will see, but what we can write here is certainly as valid as what we can read from that big media corporation ...
All I can say is that GPWS warnings during go around phases are already documented facts with some very very scary situations.
AEC,
We will see, but what we can write here is certainly as valid as what we can read from that big media corporation ...
All I can say is that GPWS warnings during go around phases are already documented facts with some very very scary situations.
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Originally Posted by BOAC
Not forgetting, of course, that in a sim, the disorientating illusion of being tilted back during a real g/a is created by - tilting you back....................
When my dentist tilts the chair back, I feel a zero-g sort of sensation as the force supporting my back drops to nil and I fall backwards. When I use full wellie in an auto transmission car the force on my back pushes me forward continuously for an extended period of time. Totally different sensation.
And once the sim seat is tilted back to say 45 degrees the total is still 1g, whereas in a real sitation it would be 1.4g. I think I would notice the difference.
But I do accept the traditional model of somographic illusion where all 1g blind manouevres seem like level flight.
mike-wsm
When my dentist tilts the chair back, I feel a zero-g sort of sensation as the force supporting my back drops to nil and I fall backwards.
When my dentist tilts the chair back, I feel a zero-g sort of sensation as the force supporting my back drops to nil and I fall backwards.
franzl
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mike - start here. It is all to do with the balance organs.
By the way, I would hope your 'full wellie' actually 'pushes you back', otherwise take your car back to the garage
By the way, I would hope your 'full wellie' actually 'pushes you back', otherwise take your car back to the garage
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Outsmarting Einstein over here
BOAC: when Mike's Bentley rushes forward obedient to Mike's full wellie, his seatback pushes him forward, methinks.
RD
RD
Last edited by RegDep; 18th Jun 2010 at 21:23. Reason: Typo
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This is going well off topic, but do you see Mike being pushed out of the front of the car or sliding towards the back? Let's return to the effect of illusions on the body, not a Newtonian discussion.
We began by pointing out that pilots do not get full acceleration experience in a simulator and
the 'acceleration' felt in a simulator is false and
pilots do not normally do full power go-rounds.
We began by pointing out that pilots do not get full acceleration experience in a simulator and
the 'acceleration' felt in a simulator is false and
pilots do not normally do full power go-rounds.
Simulators have tilt, but not acceleration*.
See slides 18-20 of the presentation 'Spatial Disorientation' at aviation.org / library .
The false climb illusion is predominantly triggered by acceleration.
* Except the really clever and expensive ones.
Alternative link
See slides 18-20 of the presentation 'Spatial Disorientation' at aviation.org / library .
The false climb illusion is predominantly triggered by acceleration.
* Except the really clever and expensive ones.
Alternative link
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76-er,
Some more information below to answer your question about the go around logic for the Airbus. This is from the FCTM, in blue :
The go-around phase is activated when the thrust levers are set to TOGA full fwd position, there is no other switch or button to press The FDs are displayed automatically and SRS Speed Ref Sys and GA TRK modes engage. The missed approach becomes the active F-PLN and the previously flown approach is strung back into the F-PLN.
The SRS mode guides the aircraft with a maximum speed of VLS, VAPP, or IAS
at time of TOGA selection (limited to maximum of VAPP + 25 with all engines
operative or VAPP + 15 with one engine inoperative) until the acceleration
altitude where the target speed increases to green dot. The pitch up can be phenomenal if the go around is initiated at higher speed like VAPP + 40
If TOGA thrust is not required during a go-around for any reason, e.g. an early
go-around ordered by ATC, it is essential that thrust levers are set to TOGA
momentarily to sequence the F-PLN and to trigger the SRS mode.
The recommended procedure is to set the thrust levers to the TOGA position for one second or two to activate the overall logic and to bring them back to the MCT detent or even the CLB detent before the output thrust is too significant.
Some more information below to answer your question about the go around logic for the Airbus. This is from the FCTM, in blue :
The go-around phase is activated when the thrust levers are set to TOGA full fwd position, there is no other switch or button to press The FDs are displayed automatically and SRS Speed Ref Sys and GA TRK modes engage. The missed approach becomes the active F-PLN and the previously flown approach is strung back into the F-PLN.
The SRS mode guides the aircraft with a maximum speed of VLS, VAPP, or IAS
at time of TOGA selection (limited to maximum of VAPP + 25 with all engines
operative or VAPP + 15 with one engine inoperative) until the acceleration
altitude where the target speed increases to green dot. The pitch up can be phenomenal if the go around is initiated at higher speed like VAPP + 40
If TOGA thrust is not required during a go-around for any reason, e.g. an early
go-around ordered by ATC, it is essential that thrust levers are set to TOGA
momentarily to sequence the F-PLN and to trigger the SRS mode.
The recommended procedure is to set the thrust levers to the TOGA position for one second or two to activate the overall logic and to bring them back to the MCT detent or even the CLB detent before the output thrust is too significant.
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Originally Posted by safetypee
Simulators have tilt, but not acceleration...[e]xcept the really clever and expensive ones.........
The false climb illusion is predominantly triggered by acceleration.
The false climb illusion is predominantly triggered by acceleration.
I realise that this egg-sucking missive will be read by certain grannies who know how to already, but I crave indulgence, for there are obviously those who don't and this note is addressed to them.
From a given starting point and velocity, the integration (integral calculus) of acceleration over time gives a unique path through space. Starting from, say, (velocity vector) 140 kts Vapp and 3° downward FPA wrt Earth coordinates, and point-in-space X some 200 ft above a runway, there is a unique path described by the accelerations experienced by the aircraft.
To reproduce those accelerations, the sim starts from 0 kts (and therefore no need for a reference direction). And it ends up ...... in the same place (somewhere within the small spatial box which bounds its movement limits).
To get the exact path followed by the simulator if it is tracking the aircraft exactly, take the unique path followed by the aircraft, and subtract the starting velocity velocity. from the velocity vector at each point. It does not require much imagination (I hope!) to see that such a path will very quickly pass outside the bounding box of the sim.
Conclusion: the sim cannot reproduce the accelerations experienced by a real aircraft performing a real accelerated manoeuvre except over a short period of time sufficient to retain that manouevre within the bounding box. That is a short period of time!
That all follows from basic first-semester calculus.
Now for the accelerations. Suppose you are sitting more or less upright in an aircraft with a shallow nose-up pitch angle and constant velocity. Let's use pilot-coordinates as our coordinate system (same as aircraft coordinates, but for pilot). Your state, with your weight vector tilted 3° in the negative-x direction, can be veridically reproduced in the sim by tilting you to the same nose-up pitch angle. Suppose you are in a lightly-loaded aircraft and put in TOGA thrust, and pitch up to, let's say 14° (which takes a second or two, we hope). First, your mass vector is being tilted relative to you (as origin of coordinates) from 3° back to 14° along negative-x. Second, you are being accelerated in the postive-x direction by many kNewtons generated by those large motors. The sim can give you a bit of a shove to start with, but it can't move you out of the bounding box, so after giving you the shove, it has got to let up. Whereas those motors go on shoving.
Newtonian mechanics and unique path. The sim can trick your body into thinking it is being momentarily accelerated by doing so, by reproducing the acceleration starting from a different velocity vector. But then your mind must do the rest, keeping you thinking your body is being accelerated when in fact it is not.
If the sim designers have done their job, then your mind is going to be thinking, yes we are still accelerating heavily after 20 seconds. But you ain't. And the real thing is going to feel different. There will be considerably more force on the body in the real thing. After that initial shove, the sim is working entirely on your body weight, whereas the real scenario is body weight plus all those kN from the motors.
Similarly, everybody has "simulated" what it is like to be in a Formula 1 car at the start of a race, by driving away from traffic lights in the Mini. But it ain't the same thing. And you can't reproduce the feeling by replacing the Mini windshields with plasma screens, and tilting the driver's seat back as the Mini accelerates off and the screen views with them. Body weight plus a bit of PS does not equal body weight plus an order of magnitude more PS.
What you can try to do is catalog a list of motion illusions. That is what some aviation psychologists do. And then investigate motions in the sim that appear able to trigger those illusions in most pilots. And then program your sim to generate those motions. You may be successful. You may find ways to make your Mini give the impression to its driver that heshe is really in an F1 car. But it can't be the same. More applied force is *always* felt, unless you're dead and gone.
[BTW, this point is a different one from the discussion about whether sims can mimic aerodynamic behavior, say up to and beyond a fully-stalled wing, which aren't known in detail. Of course you can't program a machine to mimic a behavior whose progress you don't actually know. This seems to be a perennial sticking point also.]
PBL
PBL
If the sim designers have done their job, then your mind is going to be thinking, yes we are still accelerating heavily after 20 seconds. But you ain't. And the real thing is going to feel different. There will be considerably more force on the body in the real thing. After that initial shove, the sim is working entirely on your body weight, whereas the real scenario is body weight plus all those kN from the motors.
If the sim designers have done their job, then your mind is going to be thinking, yes we are still accelerating heavily after 20 seconds. But you ain't. And the real thing is going to feel different. There will be considerably more force on the body in the real thing. After that initial shove, the sim is working entirely on your body weight, whereas the real scenario is body weight plus all those kN from the motors.
It is not my intention to disqualify simulator flying at all. But assuming a situation with spatial disorientation during TOGA could have happened like in the Gulf-Air Accident, a training situation like that will probably not happen in the simulator, or are they meanwhile as good as real live concerning movement and enviromental reality?
So the simulator is very valuable for procedural training, in this case we are discussing here it might even be counterproductive. You might expect the artificially generated feeling known from sim missions (heavy weight go-around with less than TOGA power and simulated acceleration) and might be totally surprised by the real thing (light weight, TOGA power, real life acceleration). Combine that with sudden loss of outside visual clues and a bad instrument crosscheck.....
Now i know, why we did instrument training in the T-37 and T-38 in the rear cockpit and under the hood, depriving you from any kind of outside visual reference but subjecting you to the real feeling for a complete mission from departure till landing.
franzl
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Originally Posted by CONF_iture
The recommended procedure is to set the thrust levers to the TOGA position for one second or two to activate the overall logic and to bring them back to the MCT detent or even the CLB detent before the output thrust is too significant.
When reading all these posts how bad modern technology and automation is, I have to seriously wonder how many here are really experts/ professionals. There are for sure many, you can take that from their posts. BUut there is also a number where I really have to wonder...
If you simply compare the statistics for the new fangled flying computers B777 + Airbus 340 with the really good old 707/727/DC8... whatever, you would notice that the two modern things have caused to date 0 fatalities, whereas you can count the fatalities in the good old iron in the 1000's (for each of them btw.).
And this after ~1200 of them being in service to date after almost two decades.
So much for the general statement: Áutomation is only meant to replace pilots and to kill people.
A more rational approach to this topic might be wise.
Indeed automation causes a new kind of problem. That is the communication problem between man and machine.
The criticism which I can fully understand is that airlines might be sometimes temtped to abuse the increased automation to decrease the qualification requirements for their pilots which is a BAD mistake !
Automation avoids a lot of unnecessary accidents but it also asks a lot of the pilots if something goes wrong. Then it's not as simple as pushing the yoke or pulling it anymore to save the day.
If you simply compare the statistics for the new fangled flying computers B777 + Airbus 340 with the really good old 707/727/DC8... whatever, you would notice that the two modern things have caused to date 0 fatalities, whereas you can count the fatalities in the good old iron in the 1000's (for each of them btw.).
And this after ~1200 of them being in service to date after almost two decades.
So much for the general statement: Áutomation is only meant to replace pilots and to kill people.
A more rational approach to this topic might be wise.
Indeed automation causes a new kind of problem. That is the communication problem between man and machine.
The criticism which I can fully understand is that airlines might be sometimes temtped to abuse the increased automation to decrease the qualification requirements for their pilots which is a BAD mistake !
Automation avoids a lot of unnecessary accidents but it also asks a lot of the pilots if something goes wrong. Then it's not as simple as pushing the yoke or pulling it anymore to save the day.
Ut Sementem Feeceris
Thanks PBL. You made a complex topic understandable. I strongly suspect that if the leaked info regarding this crash turns out to be true, we will be teaching this in the sims (with their associated limits) within a few months. After AF447 (A330 into Atlantic) Airbus issued training guidance for unreliable airspeed. It seems that somotogravic illusion is an insidious killer which can catch even the most experienced and of course it's usually close to the ground.
From memory I think that SRS is limited to 18.5 degrees or 22? In AlphaFloor. Of course if it's being manually flown then it would be possible to exceed these limits ..... But AlphaFloor/AoA protection will be activated VERY soon if huge pitch is demanded. AlphaFloor tends to be associated with "low speed" but it is an autothrust protection. When I demonstrate it in the sim I show guys that you can get alpha floor at 280knots IAS quite easily.
Good discussion.
A4
From memory I think that SRS is limited to 18.5 degrees or 22? In AlphaFloor. Of course if it's being manually flown then it would be possible to exceed these limits ..... But AlphaFloor/AoA protection will be activated VERY soon if huge pitch is demanded. AlphaFloor tends to be associated with "low speed" but it is an autothrust protection. When I demonstrate it in the sim I show guys that you can get alpha floor at 280knots IAS quite easily.
Good discussion.
A4
henra
Indeed automation causes a new kind of problem. That is the communication problem between man and machine.
The criticism which I can fully understand is that airlines might be sometimes temtped to abuse the increased automation to decrease the qualification requirements for their pilots which is a BAD mistake !
Automation avoids a lot of unnecessary accidents but it also asks a lot of the pilots if something goes wrong. Then it's not as simple as pushing the yoke or pulling it anymore to save the day.
Indeed automation causes a new kind of problem. That is the communication problem between man and machine.
The criticism which I can fully understand is that airlines might be sometimes temtped to abuse the increased automation to decrease the qualification requirements for their pilots which is a BAD mistake !
Automation avoids a lot of unnecessary accidents but it also asks a lot of the pilots if something goes wrong. Then it's not as simple as pushing the yoke or pulling it anymore to save the day.
Is there anything in the pipeline to change that?
franzl