[Simon]

Originally Posted by SVass 

Boeing engineers trust pilots more than they trust computers or their software.

Blanket statement. And wrong too.

In any modern airliner it's never about pilot vs. computer. They always work together, by design.

[Simon]

And more...



Looks like it could be part of one of these crew rest containers that are installed in the cargo bay.

[imitchellg5]

Originally Posted by Simon 

Blanket statement. And wrong too.

In any modern airliner it's never about pilot vs. computer. They always work together, by design.

While that's true, Boeing emphasizes pilot involvement more than Airbus does.

[Simon]

Again, although Boeing does things differently than Airbus, they also do things differently across their own line. Computer involvement varies greatly for example between the 737, 747, and the 777. Just like there are significant differences between the A300 and the A330 when it comes to FBW for example.

Saying Boeing does A while Airbus does B is too simple. There are a lot of subtle differences but also conceptual similarities that go far beyond the scope of a two-line forum post.

[chabig]

Originally Posted by imitchellg5 

While that's true, Boeing emphasizes pilot involvement more than Airbus does.

This post makes no sense to me. In both designs, the pilot commands the computers and the computers move the control surfaces in response to pilot commands.

[turtle777]

Originally Posted by chabig 

This post makes no sense to me. In both designs, the pilot commands the computers and the computers move the control surfaces in response to pilot commands.

More automation vs. less, maybe ?

-t

[chabig]

No. In both designs, it's all computer.

[driven]

Originally Posted by Simon 

Again, although Boeing does things differently than Airbus, they also do things differently across their own line. Computer involvement varies greatly for example between the 737, 747, and the 777. Just like there are significant differences between the A300 and the A330 when it comes to FBW for example.

Saying Boeing does A while Airbus does B is too simple. There are a lot of subtle differences but also conceptual similarities that go far beyond the scope of a two-line forum post.

The 747 is an antique. The fact that it's still flying is a testament to how well designed it was. I remember flying jump seat in a 747 converted to cargo use back in the 80s. The darn thing still had a small viewport in the roof for sextant !! (Amazing how much we've come to rely on computers and GPS in such a short period of time.)

[imitchellg5]

Originally Posted by turtle777 

More automation vs. less, maybe ?

-t

Yes, like in the 777 electronics are moving hydraulics, in the A330, electronics move electronics.

[Simon]

Originally Posted by driven 

The 747 is an antique.

There is no 747 per se.

The cargo converted 741/2 you flew with back in the 80s has very little to do with a modern 744ER in this respect. In my example I used planes Boeing sells right now. They vary greatly. I emphasize that there is no such thing like "Boeing does xyz while Airbus does uvw". It depends very much on the models you look at.

[Simon]

More sad pics.

[Phileas]

Originally Posted by imitchellg5 

Yes, like in the 777 electronics are moving hydraulics, in the A330, electronics move electronics.

How do you mean? Sooner or later you'll have to move hydraulics whatever the make.

[Simon]

Flight 447's perfect storm
By Patrick Smith



June 8, 2009 | The gist of the accident appears pretty clear: Air France Flight 447 was victimized by a terrible storm.

How the airplane got into this storm, and what exactly happened once it got there, are two fascinating, if perhaps unanswerable questions. The plane's flight data recorder and cockpit voice recorder -- the proverbial black boxes -- are apparently lodged amid undersea mountains, beneath thousands of feet of water.They may stay there forever.

And so we are left to speculate -- as to how an experienced crew, at the controls of a $100 million jetliner, could have found itself in such deadly circumstances.

Pilots are well aware of the dangers posed by thunderstorms -- extreme turbulence, windshear, lighting and hail. From their very first flying lesson they are trained to avoid them. And they do. There are no daredevils in a professional airline cockpit -- no pressure to push on through, no macho risk-taking. Pilots are not on a suicide mission, and will not put themselves, their passengers or their aircraft in jeopardy. Take my word for it, a crew will sooner divert or return to the departure point before it plunges into a violent storm.

I have a hard time believing the Air France pilots would have been so reckless as to fly into an area of expectedly violent conditions.

And, as I wrote last week, thunderstorms in the notorious inter-tropical convergence zone (ITCZ), where Air France met its fate, tend to be large, tall and powerful. But they also tend to be isolated and comparatively easy to circumnavigate. I fly through the ITCZ pretty regularly. Honestly, I'd rather deal with thunderstorms in that region than at higher (or lower) latitudes, where they tend to be embedded and more insidious.

So what in the world happened?

It's tough to say, but one of the most fascinating things I've come across since the accident is the graphic seen at the top of this column. You can also view it here, Figure 9 about a third of the way down the page.

This "probable radar depiction image," was created by Tim Vazquez of WeatherGraphics.com. It uses satellite data to replicatewhat the pilots of Air France 447 were probably looking at on their on-board radar screen as they approached the area of weather.

Bypassing this line of storms altogether would have incurred a long detour to the west. Meanwhile, note the contours of what they had in front of them. It's possible to stay in the green (lighter precipitation and less turbulence, presumably) the whole way through. Other visual cues that indicate danger -- scallops, fingers, hooks, areas of attenuation -- look to be avoidable.

It was going to be rough, no doubt, and we'll never know for sure what their radar screens actually showed. But if the graphic is close to accurate, it becomes easier to understand why they went on through. It was a borderline call, but not a crazy one.

Once they were inside, threading that needle, something happened. What, precisely, we don't know, but it certainly wasn't anything they were expecting.

To be honest, conditions in the vicinity of storms aren't always easy to predict, and no, not every cumulonimbus cell is successfully skirted. Things can change fast and nasty weather can sometimes close in around you. Passengers see the occasional flash of lightning and feel the occasional jolt of turbulence on those occasions when things turn out rougher than expected.

Rarely, though, do conditions become outright dangerous. This may have been an exception,a perfect storm, if you will.

My hunch is that an unusually potent lightning strike set off a cavalcade of serious electrical problems. As reviewed in this column last week, airplanes are hit by lightning fairly frequently. Although strikes aren't normally hazardous, when trouble does occur, it tends to affect the electrical system.

According to automatic status messages relayed from the airplane to its maintenance staff in Paris, the plane suffered a loss of its Air Data Inertial Reference Unit (ADIRU) and Integrated Standby Instrument System (ISIS). Other messages told of a degraded condition in the jet's high-tech, fly-by-wire flight control stem (evidently triggered by multiple electrical faults) and what seems to have been a loss of cabin pressure.

In layperson's terms, they were losing the ability to maintain speed, altitude and pressurization as well as some of their maneuverability. Under different conditions, these malfunctions aren't liable to be catastrophic. But in the throes of a storm, in darkness, it's a different story. Eventually there was total loss of control, and the plane hit the ocean in one or more pieces.

Crew incapacitation (hypoxia as a result of the decompression) is another possible factor. On the A330, the model of airplane that crashed, loss of cabin pressure can result from certain electrical failures. So the automated status message indicating depressurization may not have been a structural issue or indicator of an in-flight breakup, as many have purported.

The crew was dealing with the loss of important instruments and controls. There would be confusion at this point, with warnings going off, messages flashing and some very urgent troubleshooting. If, as part of the mix, the cabin had suddenly decompressed, it may not have been noticed right away. Without use of supplemental oxygen, the pilotswould have had about 30 seconds of useful consciousness -- maybe less.

Could they have passed out? The autopilot was off at this point, and in powerful gusts the plane could have quickly gone out of control.

Some have also posited the idea of engine failure -- the loss of one or even both engines -- caused either by hail ingestion or extreme turbulence. This could explain the loss of cabin pressure and even the loss of control. Gliding, without engines or primary instruments, is relatively easy in calm, daylight conditions, as Capt. Sullenberger showed us. But this was another situation entirely.

And over the past few days, the media has become fixated on a report that the pilots were operating at the "wrong speed" as they penetrated the bad weather. Commercial aircraft have a so-called "turbulence penetration speed" that helps ensure structural integrity and controllability during very rough air. Of course, maintaining a precise speed can be difficult under such conditions, and any discrepancy was probably a symptom of other internal failures (see electrics, above) and not by itself a cause of the accident. The news has really jumped on this topic, but I'm wary of how relevant it might be.

The speed discrepancy has been traced to the possible failure of one or more the plane's so-called "pitot tubes" during unusually heavy icing conditions. These tubes -- among the many sundry probes, ports and sensors that dot a jetliner's exterior -- help determine airspeed. Conceivably, a pitot malfunction could have caused very serious problems and, if taken to the extreme, loss of the aircraft.

All exterior probes are heated, however, and ice accretion would have to have been particularly rapid and intense to overcome them. This was possible, but not likely. If they iced over, I suspect it was due to one or more electrical failures occurring first. Again, a symptom and not a cause.

Flight 447's perfect storm | Salon Technology

[driven]

Originally Posted by Simon 

There is no 747 per se.

The cargo converted 741/2 you flew with back in the 80s has very little to do with a modern 744ER in this respect. In my example I used planes Boeing sells right now. They vary greatly. I emphasize that there is no such thing like "Boeing does xyz while Airbus does uvw". It depends very much on the models you look at.

I still do not believe that any 747 has fly by wire. (Although I heard that the forthcoming 747-800 may have some carbon fiber materials)

[chabig]

That's correct. You can't go back and make a non-FBW design FBW. It has to be built in from conception (or you spend big big bucks, which no manufacturer in the history of aviation has ever done).

[driven]

Originally Posted by chabig 

That's correct. You can't go back and make a non-FBW design FBW. It has to be built in from conception (or you spend big big bucks, which no manufacturer in the history of aviation has ever done).

Probably the biggest change you'll see on older planes is a migration to a glass cockpit. Maybe some lighter/stronger building materials, but I can't see many other changes over time.

[Simon]

Originally Posted by driven 

I still do not believe that any 747 has fly by wire.

That is correct. So Boeing, just like Airbus makes both FBW and non-FBW airliners. Let me point out that the reason isn't that one company believes in them and the other doesn't. The difference is simply age. Airbus fully implemented it with the A320 IIRC. The earlier A310 and A300 didn't have it. Boeing started with the 777. The 787 will of course have FBW too. The older 737 and 747 (older by design, not manufacturing) don't.

[chabig]

Exactly right Simon. No airliner built by Boeing or Airbus will ever again be built with mechanical controls.

[chabig]

FYI to all. I fly and teach Airbus pilots. Just to clear up any misinformation--no electrical failure will cause loss of cabin pressure.

[Simon]

There's a lot of buzz on aviation forums about this pic.



The rudder is still fully connected to the vertical stabilizer so it's definitely not comprable to AA587. (not a huge surprise considering the differences in design)

OTOH there is some speculation about the fact that the entire stabilizer is intact. Some say it's a strong indicator that the plane disintegrated already in mid-air. Apparently the stabilizer would have been blown to smithereens if it was attached to the plane when it impacted the water.

[Andrew Stephens]

Out of interest. How would they go about looking for/recovering the flight data recorders in this sort of situation. They must be pretty deep. Or pretty much anywhere on the ocean floor.

Needle/haystack?

[moep]

Originally Posted by Andrew Stephens 

Out of interest. How would they go about looking for/recovering the flight data recorders in this sort of situation. They must be pretty deep. Or pretty much anywhere on the ocean floor.

Needle/haystack?

The flight recorder sends a signal (no idea what kind though) for 30 days which aids in recovery. From what I’ve read there’s a french submarine headed to the crash area right now, trying to pick up said signal.

[Simon]

There's a device called a pinger which is fastened to the CVR and the FDR. It will send out an rf signal for about 30 days. The idea is to locate that signal.

The area they need to check has by now reached 200,000 square km, about the size of the UK. In that area the depth is enormous, and after the 30 days the pinger runs out of battery.

Apart from all of that, the boxes could be hidden underneath debris or cliffs making it difficult to pick up the signal. The French have deployed one of their nuclear subs to the area, but I don't know how far they can dive. If the pinger is below some oceanic ridge at -10000 feet I doubt the sub will be of much use. And even if the signal is located in time, the CVR/FDR actually need to be fetched. There are not very many vessels capable of that kind of deep sea recovery. Meanwhile the boxes might be damaged and salt water at gigantic pressure is corroding away... It's quite an endeavor actually.

[Edit: Oops, looks like moep was faster.]

[Atheist]

Originally Posted by Simon 

On the A330, the model of airplane that crashed, loss of cabin pressure can result from certain electrical failures.

Originally Posted by chabig 

FYI to all. I fly and teach Airbus pilots. Just to clear up any misinformation--no electrical failure will cause loss of cabin pressure.

Seems to be some disagreement here. Anyone have a definitive answer.

[Simon]

Chabig said he's actually an instructor for Airbus pilots. What I posted was a quote from a column written by a well-respected pilot who however does not fly Airbus.

I'm not sure who's right (Chabig, are you familiar with the A332 layout?), but I'd put my money on Chabig.

[Simon]

More doubts... (the "your theories" part refers to Patrick's latest Salon column)

From AF447 - PPRuNe Forums and Letters: Flight 447's perfect storm - Salon

Quite a number of posts there from Airbus pilots and mechanics. Based on the analysis there of the ACARS messages (informational messages sent out by the plane's automated maintenance monitoring system), your theories seem unlikely.

First, the "cabin pressure" warning occurs last, 4 minutes after the start of the other 23 messages. Further, that warning appears to be a "vertical cabin pressure" warning, which the posters on pprune mostly interpret as a warning that the plane is descending into higher-pressure air faster than the cabin pressure bleed can keep up - in other words, it's probably a warning caused by very rapid descent just prior to impact.

Second, ACARS apparently operates from normal electrical bus power only, not backup power (as you'd expect, because it's a luxury in an electrical power emergency). Thus, the very presence of ACARS messages would rule out total electrical failure.

Third, the sequence of ACARS messages says nothing about the electrical system per se at all. And some of those messages seem to indicate that the components in question are still functioning - for instance, the message which indicates that the planes multiple ADIRUs (redundant flight data systems) do not agree with each other (i.e., they're functioning, but cannot be relied on to provide accurate information).

Fourth, there are no messages directly relating to engine function at all.

Fifth, nearly all of the messages could potentially be traced directly to a near simultaneous (even if temporary) failure to aquire accurate airspeed data from the aircraft's multiple pitot tubes. Given that Air France and Airbus both acknowledge occasional incidents of pitot tube icing at *cruise altitude* conditions with the Airbus 330, it is small wonder that the initial focus of the investigation is on these critical sensors.

Of course, once accurate airspeed data is lost, both computers and pilots are "flying blind", which the professional pilots on pprune think would almost certainly be deadly given the aircraft's weight and altitude, and the storm conditions.

[Simon]

Chabig, another question. Is it true that Airbus pilots don't get any training in unusual altitude recovery in the event they reaching the "coffin corner"? I read that this is the case because Airbus has so many safeguards built into their system. But if the airspeed readings are skewed...

[badidea]

Originally Posted by Simon 

...Some say it's a strong indicator that the plane disintegrated already in mid-air. Apparently the stabilizer would have been blown to smithereens if it was attached to the plane when it impacted the water.

That's my theory as well - especially because of the loss of ALL electrical systems! I don't see that as a cause but as a result from what has happened up there!

[SVass]

Originally Posted by Simon 

Blanket statement. And wrong too.

In any modern airliner it's never about pilot vs. computer. They always work together, by design.

I simplified my response. You later modify yours to more precise. Now I will do the same. Having spent 30 years as a Boeing engineer and retiring long ago noting that I can only speak from a personal perspective, Boeing had computer designs that always defer to the pilot while Airbus would not allow a pilot to (easily) override a stall indication. (I have no idea what the latest systems do.) With regard to hydraulics versus electro-magnetic actuators,electronic actuators are subject to emi, lightning, and neutron induced failures. Hydraulics are not. Perhaps, we should say that Boeing engineers are more conservative and do not take as many risks in introducing modern technologies that may have faults.
sam

[badidea]

Originally Posted by SVass 

I simplified my response. You later modify yours to more precise. Now I will do the same. Having spent 30 years as a Boeing engineer and retiring long ago noting that I can only speak from a personal perspective, Boeing had computer designs that always defer to the pilot while Airbus would not allow a pilot to (easily) override a stall indication. (I have no idea what the latest systems do.) With regard to hydraulics versus electro-magnetic actuators,electronic actuators are subject to emi, lightning, and neutron induced failures. Hydraulics are not. Perhaps, we should say that Boeing engineers are more conservative and do not take as many risks in introducing modern technologies that may have faults.
sam

Are you saying that Boeing engineering is comparable Russian technology? (just joking)

I have worked for the A380, the A330 freighter and now for the A350 and all actuators I have ever seen in the fuselage (which might not be all!!) were hydraulic and not electro-magnetic!
I have absolutly no knowledge about the wings and VTP though!

[imitchellg5]

Originally Posted by moep 

The flight recorder sends a signal (no idea what kind though) for 30 days which aids in recovery. From what I’ve read there’s a french submarine headed to the crash area right now, trying to pick up said signal.

If it's French, it's probably headed away from the area.

[voodoo]

Originally Posted by Simon 

Chabig said he's actually an instructor for Airbus pilots. What I posted was a quote from a column written by a well-respected pilot who however does not fly Airbus.

I'm not sure who's right (Chabig, are you familiar with the A332 layout?), but I'd put my money on Chabig.

I'd put my money on Chabig as well.

[driven]

Article today says that at least two of the passengers on the plane matched names on the terror watch list.

[Simon]

Pfft. My 98 year old grandma's on that list.

[driven]

Originally Posted by Simon 

Pfft. My 98 year old grandma's on that list.

You might be referring to the "no fly" list, which AFAIK, is different.

[turtle777]

Originally Posted by driven 

Article today says that at least two of the passengers on the plane matched names on the terror watch list.

Tom Smith ?
John Doe ?

-t

[driven]

Hey, I'm just reporting what the article said.

I'd like to think that the folks raising such flags wouldn't raise them for "John Smith" or "Tom Doe".

Until we find out what caused this plane to go down (IF we find out) I'd say keep an open mind to all possibilities.

[chabig]

Originally Posted by Simon 

Chabig, another question. Is it true that Airbus pilots don't get any training in unusual altitude recovery in the event they reaching the "coffin corner"? I read that this is the case because Airbus has so many safeguards built into their system. But if the airspeed readings are skewed...

I tend to write short responses that don't go into much detail. But on the cabin pressure issue (I teach the A320, and as far as I know that A330 would be the same), there are two computers called cabin pressure controllers (CPCs). On any particular flight, one of the computers manages the cabin pressure and the other computer waits patiently in case it's needed to take over. Both of these computers are powered by the airplane batteries, and in case of total electrical failure the batteries still power the CPCs and all pressurization functions continue to work. So no electrical malfunction will cause a loss of pressure (sudden or otherwise). However, pneumatic air from the engines is required to keep the airplane pressurized, so a loss of both engines will result in a gradual loss of cabin pressure over a period of minutes.

On the subject of unusual attitudes, my airline is required to train pilots of all types on unusual attitude recognition and recovery every 18 months. As far as I know, this is an FAA requirement and it would be similar for all US certificated carriers. I don't know what European carriers do. It really has nothing to do with a "coffin corner". Modern airliners don't fly anywhere that point.

Chris

[Doofy]

Originally Posted by driven 

Article today says that at least two of the passengers on the plane matched names on the terror watch list.

Two passengers on doomed Air France jet had names linked to Islamic terror groups | Mail Online

[Simon]

Chabig, thanks for the detailed reply.

Originally Posted by chabig 

I don't know what European carriers do. It really has nothing to do with a "coffin corner". Modern airliners don't fly anywhere that point.

So in your opinion, is all this talk on the web about how they possibly had an only 60-80mph safety margin between stall speeds (as a result of the weather conditions, their airspeed, attitude, and altitude) complete nonsense?

[Simon]

Originally Posted by Doofy 

Two passengers on doomed Air France jet had names linked to Islamic terror groups | Mail Online

Two passengers on doomed Air France jet cleared of links to Islamic terrorism
Two men aboard doomed Air France Flight 447 have been cleared of having links to Islamic terrorism, it has been revealed.
Posthumous security checks into the backgrounds of the men found that they solely ‘shared the same name’ as known Islamic radicals, even though their bodies have not yet been found.

So if it took a thorough 'background check' to find that out it makes you wonder how they got on that list in the first place.

You just gotta love those terror lists. Thank God my name's not John Smith. There's bound to be a John Smith somewhere with ties to some 'terrorist' organization. Just imagine what happens every time a John Smith boards a plane somewhere. I marvel the tactics of these 'anti-terror units'. I just feel so much safer flying!

[Spheric Harlot]

What's even more amazing is that some "news" service found it necessary to report it - though of course, it's mostly about just having *something* to report when nothing else is known.

Corpse collections don't make headlines.

[Simon]

Yeah, that seems to be the case. Now that enough actual aviation pros have gone on record saying there are no quick conclusions to be drawn from what is known so far the papers are frantically looking for something to print.

Corpse collections however make for great picture series. And that's even cheaper than researching the facts and writing about it.

[Kerrigan]

Yea, the whole thing about that terror list is ridiculous.

Even though the circumstances of the crash are shrouded in mystery, it was completely irresponsible, even risible, that the French intelligence agency should have investigated a possible link to terrorism.

I mean, it's not like it's their job to keep terrorists off planes or to investigate possible clues. How absurd!

(OK but seriously, I do agree that reporting this as a major headline story is going too far)

[Doofy]

Originally Posted by Spheric Harlot 

What's even more amazing is that some "news" service found it necessary to report it - though of course, it's mostly about just having *something* to report when nothing else is known.

Originally Posted by Kerrigan 

(OK but seriously, I do agree that reporting this as a major headline story is going too far)

Don't you just hate it when news websites change/update the fsking story after you've linked to it? Last night that story was about "may have links to AQ" and didn't say anything about them being cleared.

[Spheric Harlot]

Originally Posted by Simon 

Corpse collections however make for great picture series. And that's even cheaper than researching the facts and writing about it.

Actually, it's not.

Licensing press photographs for reprint is *not* cheap.

[turtle777]

Originally Posted by Simon 

Two passengers on doomed Air France jet cleared of links to Islamic terrorism
Two men aboard doomed Air France Flight 447 have been cleared of having links to Islamic terrorism, it has been revealed.
Posthumous security checks into the backgrounds of the men found that they solely ‘shared the same name’ as known Islamic radicals, even though their bodies have not yet been found.

So if it took a thorough 'background check' to find that out it makes you wonder how they got on that list in the first place.

You just gotta love those terror lists. Thank God my name's not John Smith. There's bound to be a John Smith somewhere with ties to some 'terrorist' organization. Just imagine what happens every time a John Smith boards a plane somewhere. I marvel the tactics of these 'anti-terror units'. I just feel so much safer flying!

For some people, this is actually no laughing matter.

I saw some TV special once about people in the US that share the same name as people on the "no fly" list. Some of them have been fighting for years to be able to fly again, to no avail.

Go USofA

-t

[Dork.]

Originally Posted by turtle777 

For some people, this is actually no laughing matter.

I saw some TV special once about people in the US that share the same name as people on the "no fly" list. Some of them have been fighting for years to be able to fly again, to no avail.

Go USofA

-t

If your name is Edward Kennedy, though, you can get your name cleared much more quickly! (Article is from 2004....)

[glideslope]

Originally Posted by Spheric Harlot 

Actually, it's not.

Licensing press photographs for reprint is *not* cheap.

Not directed at Spheric.

It's stratospheric in situations like this. Really demonstrates how we have deteriorated as a species.
And please, spare me any freedom of expression, or market based analysis. Been there done that.

The important item to remember when analyzing situations such as this is to not be so open minded that your brain falls out. A very frequent occurrence in these times.

[glideslope]

Originally Posted by chabig 

I tend to write short responses that don't go into much detail. But on the cabin pressure issue (I teach the A320, and as far as I know that A330 would be the same), there are two computers called cabin pressure controllers (CPCs). On any particular flight, one of the computers manages the cabin pressure and the other computer waits patiently in case it's needed to take over. Both of these computers are powered by the airplane batteries, and in case of total electrical failure the batteries still power the CPCs and all pressurization functions continue to work. So no electrical malfunction will cause a loss of pressure (sudden or otherwise). However, pneumatic air from the engines is required to keep the airplane pressurized, so a loss of both engines will result in a gradual loss of cabin pressure over a period of minutes.

On the subject of unusual attitudes, my airline is required to train pilots of all types on unusual attitude recognition and recovery every 18 months. As far as I know, this is an FAA requirement and it would be similar for all US certificated carriers. I don't know what European carriers do. It really has nothing to do with a "coffin corner". Modern airliners don't fly anywhere that point.

Chris

Excellent post Chris. Thank you.

In the 320/330 when both engines are lost what initiates the decompression alarm/transmission we saw.

1) The loss of bleed air into the cabin?

2) Or the actual pressure changing to a certain atmospheric pressure?

Mark.