Air France 447 - On topic only!

[Highkeas]

Back to pitots

From today's AIAA newsletter:

Airbus A340-600 Diverted After Weather Incident.

Flightglobal (4/2, Kaminski-Morrow) reported, "Pilots of an Etihad Airways Airbus A340-600 diverted to Singapore after a sudden encounter with turbulent weather during cruise generated unreliable airspeed data and left the jet unable to maintain altitude separation requirements." A preliminary inquiry into the incident "highlights that icing is notably a cause of unreliable airspeed indications at high altitude" but "has yet to establish conclusions about the event." According to the article, this incident bears "a similarity to those preceding the Air France flight AF447 accident in June 2009, when an A330 cruising at 35,000ft flew into a storm cell, suffering icing of its pitot system."

I wonder if these are the same model pitot as on AF447.

[3WE]

...I'm really not debating which type of airplane is safer. I'm debating whether the plane did its part in the Hudson landing and whether Sully was fair in his remarks.

Who gives a rat what the no feed-back, independent, non-traditional, non-speed holding, designed-for-dummies, autopilot, point-where-you-want-to-go control logic contributed to the Hudson landing.

The thing the Airbus contributed was to skim and hold together quite nicely.

There's a widely available video of Boeing water landing that didn't go as well.

Sully wasn't being asked what the Airbus vs Boeing did for his landing, he was being asked what the control system did for AF vs. Boeing.

[Gabriel]

There's a widely available video of Boeing water landing that didn't go as well.

That's true but unfair and biased, don't you think?
We could say that there are videos of Airbus crash-landing that didn't go as well either. But that would be apples and oranges, as much as your comparison.

[Highkeas]

.................
There's a widely available video of Boeing water landing that didn't go as well.
.....................

I'm surprised by how many aircraft (Boeing and others) made "sucessful" water landings:

http://en.wikipedia.org/wiki/Water_landing

[Leftseat86]

That's true but unfair and biased, don't you think?
We could say that there are videos of Airbus crash-landing that didn't go as well either. But that would be apples and oranges, as much as your comparison.

If he's talking about the Ethiopian 767 the two are not even comparable.


Also, nobody in this discussion has mentioned the fact that Sully was a formidable glider pilot with extensive experience, one of the best in his class at the Air Force academy? If this incident could have happened to any airline pilot in the entire United States, he very well may have been the best man for the job. Glider flying was engrained in him.

[Spectator]

There's a widely available video of Boeing water landing that didn't go as well.

There's a well known Airbus water landing that didn't go so well either, but unfortunately it was in the middle of the Atlantic in the dark so there is no video record of it.

[Gabriel]

Also, nobody in this discussion has mentioned the fact that Sully was a formidable glider pilot with extensive experience, one of the best in his class at the Air Force academy? If this incident could have happened to any airline pilot in the entire United States, he very well may have been the best man for the job. Glider flying was engrained in him.

I think you are exaggerating. The "stick and rudder" part of the equation was not tough. I mean, it's quite easy to keep a plane gliding above stall speed, level off a few feet above a plain surface, and smoothly let it mush on it.

Specific gliding skills like holding the best glide speed, taking most out of thermals or other lifting air, planning a glide to reach a specific point on the ground, etc were not applicable here. The Hudson was ling enough and free of obstacles enough that the touchdown point could have been a few miles short or long from the actual touchdown point, and several hundred feet to the sides.

I mean, what would have a "regular", non- "best-in-class Air Force glider pilot", would have done? Pull up and let it stall? (ok, the Airbus itself would have not allowed this) Not flare and dig the nose into the water? Land in a bank to dig a wingtip? Miss the river and land on the ground? Hit a bridge? Avoiding these things are quite easy even for an average pilot.

And then, the "rudder skills" part was not the best of Sully's performance, as he run out of airspeed to soon and too high, making a somehow hard touchdown instead of "skimming" the water.

The moment of truth in this accident was when Sully said "We will be in the Hudson". As himself said in an interview: "The Hudson was the only surface long enough, wide enough and smooth enough that I knew I could reach".

He had three nearby airports, simulations have shown that one of them within reach (barely) and the other two not. But he didn't have this piece of information up there. He might have thought (and he probably did) "I may reach one of them". When you face an emergency, having three airports nearby that may be within reach is a big temptation. You can save the airplane landing there.

And I would expect a not small fraction of the pilots trying to reach one of them because they thought they may reach it. Instead, Sully went for the sure thing, for a hard but survivable place that he knew he could reach. Tough but good decision.

[Black Ram]

many times people say "Airbus xxxxx because it's FBW". And that's wrong

True, but there is another reason for people to say that. Airbus has made FBW a standard since the very first A320, since that all their planes have it. The cockpits are also similar. In fact, it's hard to differentiate the cockpits of the a320, a330, a340 (hope no one calls me out on the thrust levers).

[Black Ram]

Sully wasn't being asked what the Airbus vs Boeing did for his landing, he was being asked what the control system did for AF vs. Boeing.

Right, but I was talking more about all his remarks, not just the interview on AF447. The latter, btw is fairly old news. I watched it back then, when it came out, and in the discussions some presented themselves as pilots, and said the focus in their airlines is actually pilot training, and that they were not considering the sidestick as a factor. So I guess when it comes to AF447, different pilots would have different opinions on the sidestick.

[Black Ram]

There's a widely available video of Boeing water landing that didn't go as well.

Yeah, that cheap Seattle piece of junk got squished like a coke can

Seriously, I also think that's not a fair comparison. Any plane would get damaged baldy, if it hit the water at such an angle. But that's part of my point.

Can the experts say if FBW could have helped keep the wings perfectly level.

Again, crucial for a water landing.

[Gabriel]

No FBW, no Airbus control logic, no envelope protections, no sidestick.
But, for the record, my opinion is that this is equally doable in an Airbus, not even harder than in a Boeing (even probably easier in some aspects).

An American Airlines Boeing 737-800, registration N956AN performing flight AA-693 from Fort Lauderdale,FL to Dallas Ft. Worth,TX (USA), was enroute at FL360 about 40nm north of Panama City,FL (USA) in instrument meteorologic conditions at 14:45Z when the captain's airspeed indications were removed from the display shortly followed by the captain's altitude indication. The crew decided to divert to Montgomery,AL (USA) and started the descent. During the descent the first officer's indicated airspeed and altitude indications were also removed from display, both engine (CFM56) electronic controls reverted to alternate mode. Using pitch/power relation as well as angle of attack indications the crew descended the aircraft into visual meteorologic conditions, where all indications recovered with engine control remaining in alternate mode, and diverted to Atlanta,GA for a safe landing

http://avherald.com/h?article=4603dcda&opt=0

[Gabriel]

Can the experts say if FBW could have helped keep the wings perfectly level.

Are you kidding?
To begin with, it's not FBW. You can program anything into FBW. It's someone's approach to FBW.
Second, the pilot was fighting with the kidnappers. How can a computer help with that? Or do you think that keeping the wings level is a difficult task in a non-FBW plane? And an Airbus will not level the wings by itself.

[Gabriel]

http://www.youtube.com/watch?v=uTgx0dZ-BAg

http://www.youtube.com/watch?v=PWl0TygaeDw

I hope this helps answering your question.

[Gabriel]

Seriously, I also think that's not a fair comparison. Any plane would get damaged baldy, if it hit the water at such an angle.

And don't forget a plain river vs open ocean with significant swells.

[Black Ram]

The difference is that in a non-FBW plane or a Boeing-like FBW, other than the airspeed indicator, you have another strong cue regarding whether you are slowing down or speeding up from your trim speed: The force on the yoke

I guess on the airbus it's strictly about the instruments, you have to watch the pitch angle. Which isn't a bad idea to begin with.

Maybe it is a good idea to add the AoA on the instrument panel. Also, they can warning tones for the speed dynamics, if they don't have them. I know they have them for departing planned altitude.

If it is such a big deal, it shouldn't be very hard to link the sidesticks, or put an indicator for their position. I don't think it would even be hard to add feedback, but it doesn't make sense, unless they change the flight control input system from load-factor based.