Posted on 12/30/2014 8:29:59 PM PST by barmag25
In the AF447 accident the pilot in the right seat kept pulling back on the side stick, an action unknown to the other two pilots.
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The instruments were available and giving correct information after about a minute, about when the captain returned to the flight deck. There were also stall warnings. There was no need to see what the pilot was doing with the joystick to know what was going on.
At the very least the captain should have removed one of the pilots and flown the plane.
Gotta love Fly-by-wire...not.
I have seen a Youtube video of an Airbus cockpit during a flight and the joystick movements were visible.
From what I understand some fighter jets have sticks that are pressure sensitive and don’t move. I wonder if any Airbuses have those.
Yes, there was. It's an Airbus thing.
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"Robert" is the first officer in the left seat, "Bronin" is the first officer in the right seat.
As the plane approaches 10,000 feet, Robert tries to take back the controls, and pushes forward on the stick, but the plane is in "dual input" mode, and so the system averages his inputs with those of Bonin, who continues to pull back. The nose remains high. 02:13:40 (Robert) Remonte... remonte... remonte... remonte... Climb... climb... climb... climb... 02:13:40 (Bonin) Mais je suis à fond à cabrer depuis tout à l'heure! But I've had the stick back the whole time! At last, Bonin tells the others the crucial fact whose import he has so grievously failed to understand himself. 02:13:42 (Captain) Non, non, non... Ne remonte pas... non, non. No, no, no... Don't climb... no, no. 02:13:43 (Robert) Alors descends... Alors, donne-moi les commandes... À moi les commandes! Descend, then... Give me the controls... Give me the controls! Bonin yields the controls, and Robert finally puts the nose down. The plane begins to regain speed. But it is still descending at a precipitous angle. As they near 2000 feet, the aircraft's sensors detect the fast-approaching surface and trigger a new alarm. There is no time left to build up speed by pushing the plane's nose forward into a dive. At any rate, without warning his colleagues, Bonin once again takes back the controls and pulls his side stick all the way back. 02:14:23 (Robert) Putain, on va taper... C'est pas vrai! Damn it, we're going to crash... This can't be happening! 02:14:25 (Bonin) Mais qu'est-ce que se passe? But what's happening? 02:14:27 (Captain) 10 degrès d'assiette... Ten degrees of pitch... Exactly 1.4 seconds later, the cockpit voice recorder stops
In a yoke airplane the movements are obvious because both large yokes simultaneously move exactly the same amount and direction, and are right in front of each pilot.
Side-stick airplanes, not so. It’s a huge built in barrier to communication and cooperation, or to put in industry terms, “cockpit resource management”.
Well, I’ll look to see if the side sticks were named as contributing factors in any of the investigative reports.
Airbus/French fly-by-wire. Boeing fly-by-wire does not do that, it is programmed to always let the pilot have control.
Good to know...thanks.
I fly about 3-4 times a year and the briefing by the flight attendant is to “USE YOUR SEAT BOTTOM CUSHION as a flotation device in the event you find yourself in water”.
Actually all of the Airbus aircraft are designed to be flown by pilots less skilled that most of our American trained pilots.
the “laws” mentioned in earlier posts prevent the unskilled pilot from exceeding limitations. The law partially to blame for the Air France 447 accident is that the pilot cannot stall the airplane. The flight control computers will lower the nose and all of the nose up control inputs by the pilot are futile. The AF aircraft spiraled in a flat, but nose low, attitude from high altitude to the ocean surface. These planes are designed for third world pilots and yet still dangerous.
A friend participated in an audit of KAL flight ops and remarked that he would not let any friend or family member fly them. It is a matter of a different culture. Asiana had a similar problem, fear of embarrassing the pilot flying the airplane.
The final reports seems to blame the flight director software more than anything outside of the bad piloting. There’s no mention of side-sticks.
“Usually the scheduled aircraft type will be printed on your ticket,”
OK, it will show on the ticket. But, that is after purchase.
You might want to re-read the AF447 report.
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“In accordance with common practice, the captain had sent one of the co-pilots for the first rest period with the intention of taking the second break himself.[21] At 01:55 UTC, he woke the second pilot and said: “... he’s going to take my place”. After having attended the briefing between the two co-pilots, the captain left the cockpit to rest at 02:01:46 UTC. At 02:06 UTC, the pilot warned the cabin crew that they were about to enter an area of turbulence. It is probably two-three minutes after this that the airplane encountered icing conditions (the CVR recorded what sounded like hail or graupel on the outside of the airplane, and the engine anti-ice system came on) and ice crystals started to accumulate in the pitot tubes.[22] The pilots turned the aircraft slightly to the left and decreased its speed from Mach 0.82 to Mach 0.8 (the recommended “turbulence penetration speed”).[23]
“At 02:10:05 UTC the autopilot disengaged and the airplane transitioned from normal law to alternate law 2.[24] The engines’ auto-thrust systems disengaged three seconds later. Without the auto-pilot, the aircraft started to roll to the right due to turbulence, and the pilot reacted by deflecting his side-stick to the left. One consequence of the change to alternate law was an increase in the aircraft’s sensitivity to roll, and the pilot’s input over-corrected for the initial upset. During the next thirty seconds, the aircraft rolled alternately left and right as the pilot adjusted to the altered handling characteristics of his aircraft.[25] At the same time he made an abrupt nose-up input on the side-stick, an action that was unnecessary and excessive under the circumstances.[26] The aircraft’s stall warning sounded briefly twice due to the angle of attack tolerance being exceeded, and the aircraft’s recorded airspeed dropped sharply from 274 knots to 52 knots. The aircraft’s angle of attack increased, and the aircraft started to climb. By the time the pilot had control of the aircraft’s roll, it was climbing at nearly 7,000 ft/min[25] (for comparison, typical normal rate of climb for modern airliners is only 2,000–3,000 ft/min at sea level, and much smaller at high altitude).
“At 02:10:34, after displaying incorrectly for half a minute, the left-side instruments recorded a sharp rise in airspeed to 215 knots, as did the Integrated Standby Instrument System (ISIS) another half a minute later[27] (the right-side instruments are not recorded by the recorder). The icing event had lasted for just over a minute.[28][29][30] The pilot continued making nose-up inputs. The trimmable horizontal stabilizer (THS) moved from three to thirteen degrees nose-up in about one minute, and remained in that latter position until the end of the flight.
“At 02:11:10 UTC, the aircraft had climbed to its maximum altitude of around 38,000 feet. There, its angle of attack was 16 degrees, and the engine thrust levers were in the fully forward Takeoff/Go-around detent (TOGA), and at 02:11:15 UTC the pitch attitude was slightly over 16 degrees and falling, but the angle of attack rapidly increased towards 30 degrees. A second consequence of the reconfiguration into alternate law was that “stall protection” no longer operated. Whereas in normal law, the airplane’s flight management computers would have acted to prevent such a high angle of attack, in alternate law this did not happen. (Indeed, the switch into alternate law occurred precisely because the computers, denied reliable speed data, were no longer able to provide such protection – nor many of the other functions expected of normal law).[31] The wings lost lift and the aircraft stalled.[6]”
***
The pilot trusted his tech too much, didn’t understand how the craft would fly on manual (this is the other big nasty on Airbus - if the computers start getting conflicting inputs from their sensors, they will kick you out into manual mode and then it’s your problem - and a lot of airlines do not do much training with their Airbuses in manual/’alternative law 2’ mode) and then stalled it at 38,000 feet. The aircraft simply fell 38,000 feet into the ocean at that point.
Sorry, this part didn’t make the copy and paste:
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“At 02:11:40 UTC, the captain re-entered the cockpit. The angle of attack had then reached 40 degrees, and the aircraft had descended to 35,000 feet with the engines running at almost 100% N1 (the rotational speed of the front intake fan, which delivers most of a turbofan engine’s thrust). The stall warnings stopped, as all airspeed indications were now considered invalid by the aircraft’s computer due to the high angle of attack.[32] In other words, the aircraft was oriented nose-up but descending steeply. Roughly 20 seconds later, at 02:12 UTC, the pilot decreased the aircraft’s pitch slightly, air speed indications became valid and the stall warning sounded again and sounded intermittently for the remaining duration of the flight, but stopped when the pilot increased the aircraft’s nose-up pitch. From there until the end of the flight, the angle of attack never dropped below 35 degrees. From the time the aircraft stalled until it impacted with the ocean, the engines were primarily developing either 100% N1 or TOGA thrust, though they were briefly spooled down to about 50% N1 on two occasions. The engines always responded to commands and were developing in excess of 100% N1 when the flight ended.
“The flight data recordings stopped at 02:14:28 UTC, or 3 hours 45 minutes after takeoff. At that point, the aircraft’s ground speed was 107 knots, and it was descending at 10,912 feet per minute (108 knots of vertical speed). Its pitch was 16.2 degrees (nose up), with a roll angle of 5.3 degrees left. During its descent, the aircraft had turned more than 180 degrees to the right to a compass heading of 270 degrees. The aircraft remained stalled during its entire 3 minute 30 second descent from 38,000 feet[33] before it hit the ocean surface at a speed of 152 knots (280 km/h), comprising vertical and horizontal components of 108 and 107 knots respectively. The aircraft broke up on impact; everyone on board died, presumably instantaneously.[34]”
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Dude stalled it, didn’t even realize it, didn’t try to recover and the plane fell 38,000 feet. No spiral, no flat attitude. Impact at the time the flight recorder stopped (i.e., it hit the water) was 16 degrees noseup, at almost 11,000 ft/min sink rate.
That's a superficially conclusive reading of the narrative, that neglects all the red-flag statements. Read between the lines. "Human-machine interface issues" are a hint of design flaws in the airplane, as is the quote "After the autopilot and autothrottle disengaged, as the flight control law switched from normal to alternate, the flight director’s crossbars disappeared. But they then reappeared several times. Every time they were visible, they prompted pitch-up inputs by the PF, investigators determined". The "interface issues" are compounded by what might be called 'pilot to pilot interface issues' -- one pilot has no idea what the other pilot is doing unless he says so, because the stick, unlike a yoke, barely moves, has little to no tactile feel, and isn't in the scan of the other pilot. Normal and alternate law are separate modes that only make it more imperative for the pilots to know exactly what the airplane is "thinking" (since the flight director is only as good as the commands from the central computers) and what the other pilot is doing (since under alternate law they must fly it themselves).
The fact is, this product has been defective ever since the Paris air show when a test pilot mowed down hundreds of trees with an A320 that decided his command to pull up was invalid, and it would rather push the nose over (and mow down trees). And that accident didn't have anything to do with the equally problematic side-stick configuration.
Naturally the FRENCH investigative agency is not going to directly blame faulty design philosophy issues inherent to an Airbus -- where do you the assembly line is for the A320? The A380? What governments subsidize Airbus? What do you think it would cost to redesign the Airbus to have systems that concur intuitively with a pilot's instincts? What about the costs of reconfiguring the airplane to a yoke flight control setup? Of course, it would be impossibly expensive and impractical, and probably wouldn't be done even discounting the expense, as a matter of national pride (a hint of this is the statement: "Leopold Sartorius, head of the investigation’s avionics systems working group, said he did not conduct an exhaustive study on other airliners to determine whether the flight director would have behaved in the same way").
The undeniable fact is, had the more experienced first officer (in the left seat) or the much more experienced captain (observing) known that the right-seat pilot was pulling back on the yoke persistently early on, regardless of circumstances, they would have seen that pushing the nose over was the key to recovery, instead of being confused by the persistent stall that resulted from the right-seaters' hidden side-stick inputs.
Actually, it should be possible to implement at least a partial fix in software. Program it to pop up a INPUT CONFLICT message on one or more of the MFDs. Optionally, add an addtional display showing how the two sticks diverge.
Technically, this is easy. Philosophically, it would reveal the deficiencies in the sidestick control philosophy they have invested so much into over the years. Therefore, easy or not, they won’t do it.
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