Air France 447 according to Sully [Archive]

hawkeye52

April 5th, 2013, 13:16

Very damning!

I did not know that the two side-stick controllers are not linked (as are the yokes). Of course, Airbus cannot and will not admit to any alleged deficiencies in their cockpit design -- which is common to ALL their commercial models, A319/A320/A321/A330/A340/A380 and I suppose A350. Any such admission could, conceivably, put them out of business.

Given a choice, I will avoid Airbus aircraft.

- H52

CG_1976

April 5th, 2013, 14:38

Someone can correct me please if I am wrong. I also heard there Autopilot system is kinda wonky, no redundancies like the Boeing. Where's Bone, I'd like to here from a CRJ pilot??

PRB

April 5th, 2013, 14:59

I read about this "feature" some time ago. It's an interesting problem. In the old days, the pilot with the strongest arms would win, were there to be such a battle. But how does a digital fly by wire system handle differential inputs from the two controllers? Surely this incident couldn't have been the first time the topic ever came up, at Airbus or Boeing, or any other airplane maker. There has to be some of of "I have the aircraft", "ok, you have the aircraft" logic in the flight control system. I just can't believe the system "participated" in a conflict between the two pilots, and "didn't know what to do". I to would like to hear from pilots who fly such planes. How does the system handle this situation?

Sascha66

April 5th, 2013, 15:50

Very damning!

I did not know that the two side-stick controllers are not linked (as are the yokes). Of course, Airbus cannot and will not admit to any alleged deficiencies in their cockpit design -- which is common to ALL their commercial models, A319/A320/A321/A330/A340/A380 and I suppose A350. Any such admission could, conceivably, put them out of business.

Given a choice, I will avoid Airbus aircraft.

- H52

This is very wrong! The sticks are indeed linked, although electronically. Let me insert a more knowledgable description by an A320 pilot:

"A visitor once asked me what happened if the captain moves the side stick to the left and the copilot moves it to the right? My answers were not very clear then, as I was not rated on the A320 yet.

Well, since the side sticks are only "wired", they are not mechanically interconnected like the old conventional planes. The right side cannot feel the movement from the left stick. What happens is that, when there are opposite deflections, their inputs are algebraically added (total sum) with the maximum limit corresponding to the movement of one side stick. If the captain pulls full left, and his copilot pulls full right, the net effect is zero.

So, the last pilot to click on an override push-button on the side stick obtains control (an indicator light in front of the other pilot signals this fact). The potential exists for the pilots to *fight* over the control of the side sticks. Rather than the "strongest" pilot winning, the one with the fastest thumb will win! " (Source: http://www.askcaptainlim.com/flying-the-plane-flying-90/164-flying-the-airbus-side-stick-the-one-with-the-fastest-thumb-wins.html)

This is actually quite a safe system. The actual result is similar to 2 pilots working their yokes.

Another interesting thread on this topic: http://www.airliners.net/aviation-forums/tech_ops/read.main/304407/

As a final point I would like to add that the Boeing 777 has side-stick and fly-by-wire technology as well, albeit without a safe envelope control.

I also think you misinterpreted Captain Sullenberger, in his interview on AF447 he generally raises the issue of complicated modern cockpit procedures operated by inexpereienced pilots but does not generally criticize Airbus cockpit design or fly-by-wire technology.

Edit:
Hawkeye, thank you for your last post, sir! :icon29::icon29::icon29:

Bone

April 5th, 2013, 16:13

Someone can correct me please if I am wrong. I also heard there Autopilot system is kinda wonky, no redundancies like the Boeing. Where's Bone, I'd like to here from a CRJ pilot??

Oh, hello, I heard my name called, lol. Well, the airbus system is as safe as any system can be. But, like any aircraft system that has seen thousands and thousands and thousands of flight hours, there can be the one-in-a-million "oh, we (AE's) didn't foresee that happening" issue. The problem with this crash was because the two pilots in the cockpit (Captain was on break) had very under developed stick and rudder skills, for the amount of flight time they had in their logbooks. Airbus pilots are trained to turn the auto pilot on just after take-off, and off just shortly before touchdown (if not auto landing). Adding to the problem is the long haul and ultra long haul type of flying, where the majority of hours flown are in cruise flight. In an augmented crew of three, only one guy gets to land and take-off, and the other two don't, on any gven leg. I know a number of long haul pilots who have to go to the sim every three months, to maintain their 90 day currency requirement for 3 take-offs and landings.

At Air France, a lot of the pilots get hired with only a few hundred hours, and then spend years watching the auto pilot fly the aircraft. The two FO's who were involved in this crash were hired with low time, and it's no wonder they didn't know what to do when sh*t hit the fan, because they just didn't have the skills. Very sad.

hawkeye52

April 5th, 2013, 19:11

After reading the links provided by sascha66 I have to admit my initial posting was a bit over-the-top; I should have used a smaller font for "Very Damning!" Nevertheless, I was genuinely surprised that the obvious visual cues provided by a yoke are missing from the Airbus FBW.

Sascha66's links provide a balanced view of the side-stick controversy. I came away feeling that what needs to be avoided is not so much Airbus aircraft but rather Air France -- and any other operator that employs low-time aviators with underdeveloped stick-and-rudder skills.

- H52

airtj

April 6th, 2013, 06:05

A330/A340 SIDESTICK CHARACTERISTICS

There is no physical interconnection between the sidesticks. Visual monitoring of
the other pilot's sidestick input is significantly reduced because of the sidestick
position.
With the AP engaged, the sidesticks are locked in the neutral position. This
provides a tactile feedback that the AP is engaged and also prevents
simultaneous inputs from the pilot and AP.
When the PF makes a sidestick input, an electrical order is sent to the flight
control computers. If the PNF makes a simultaneous sidestick input, both signals
are algebraically summed and both PF and PNF green lights flash on the
glareshield. This situation might occur in the case of an instinctive PNF reaction
on the sidestick. If the PNF needs to take control, he must press and hold the
take-over pb in order to avoid simultaneous sidestick inputs and announce, "I
have control".
In the case of a SIDESTICK FAULT ECAM warning due to an electrical failure,
the affected sidestick order sent to the computers is zeroed. This means that the
affected sidestick has been deactivated and there is no further procedure
associated with this warning.
In the case of pilot incapacitation where a sidestick input is being made, or in the
case of a mechanical failure leading to a jammed sidestick, the inputs are again
algebraically summed. There is no associated ECAM caution. In either of these
cases, the intervening pilot must press the take-over pb to gain single sidestick
authority. The pb must be depressed for at least 40 seconds to permanently
deactivate the affected sidestick. However, if a sidestick has been deactivated, it
may be reactivated by depressing its take-over pb.

pfflyers

April 6th, 2013, 06:33

Just to clarify a statement posted above, for the record Boeing has not adopted a sidestick control system in any commercial transport they are currently building including the 777 and 787. They have in fact, adopted "fly-by-wire" technology in their new models but retained their old-fashioned yokes which are still linked.

hawkeye52

April 6th, 2013, 06:51

"As a final point I would like to add that the Boeing 777 has side-stick and fly-by-wire technology as well, albeit without a safe envelope control."
- Sascha66

"Just to clarify a statement posted above, for the record Boeing has not adopted a sidestick control system in any commercial transport they are currently building including the 777 and 787. They have in fact, adopted "fly-by-wire" technology in their new models but retained their old-fashioned yokes which are still linked."
- pfflyers

Thanks for clarifying, pf; I was wondering about that!
- H52

pfflyers

April 6th, 2013, 07:28

Getting back to the accident, I have read several posts in other forums from actual Airbus pilots that place the blame for this squarely on the crew. Most particularly they point to a lack of effective CRM. None of them criticized the aircraft design. It appears an inexperienced crew induced an unrecognized stall and failed to take proper recovery steps. Certainly the darkness, the storm, and loss of some instrumentation were contributing factors.

Bone

April 6th, 2013, 07:38

Never mind that the stick controllers don't have the ability to move in an interconnected way, the system isn't the problem. Airbus pilots are used to it. Think about why both guys were on their respctive sticks at the same time, moving the sticks with completely different inputs from each other. One guy can only be on the controls at a time. Usually stated by saying "I have the controls"...that's pretty much the standard in the USA, anyway.

The saddest thing here is that if they had both stopped moving their sticks around, the plane would have likely recovered to a flyable condition on it's own.