The Duchess of Zeon wrote: Though it seems they're playing up the difficulty of manually operating an aircraft at speed, the weather data would presumably not lie, and that is a somewhat worrying possibility, that this is a more systematic failure in the Airbus control system after all.
Yeah, they are playing up the difficulty of flying the jet - what they say doesn't jibe with what I've heard from people who actually fly Airbuses. Is it
harder to fly without some of the automatic systems? You bet - but it's hardly impossible.
There's certainly nothing wrong with looking at
everything that could have possibly gone wrong but I suspect some of that article is looking for something sensational to talk about as right now all there really is in the way of a facts is 1) an airplane crashed, 2) no survivors, 3) no black boxes, and 4) next to no wreckage. We've known that for days, nothing really new here.
A series of messages sent automatically by the jet moments before it plunged into the ocean late Sunday with 228 passengers and crew members aboard has raised speculation that the crash might have involved a malfunction of the automated system that flies the plane most of the time.
Really? Because yesterday the media was saying it was an indication the airplane had broken up.
One of the messages reported that one of the plane's navigational control units had failed and that, almost simultaneously, the autopilot system had disengaged.
Autopilots are
designed to disengage when things get wonky, having it shut down is NOT a failure!
The sequence of events forced the crew of Flight 447 to fly the jet manually, a difficult task on an Airbus traveling at high altitude near its maximum speed, aviation experts said.
Who are these experts and what are their credentials?
Any significant change in airspeed could have caused the plane to lose lift or stability, both potentially deadly conditions.
Yes, airliners at altitude are in slowflight or something close to it. So fucking what? Even if you
did stall one at 35,000 feet there is still plenty of altitude in which to recover assuming nothing else went wrong (granted, given that there has been a crash, several things probably did go wrong) and by the time recovery occured you'd be in thicker air with a larger envelope for flight. Flying an Airbus manually is more work, but it's well within the capability of the guys in the cockpit.
Meanwhile, new analysis of the weather in the vicinity at the time of the crash appears to cast doubt on earlier reports that the plane encountered severe thunderstorms, lightning and wind gusts. Though there were storms, they were almost certainly less intense than those sometimes encountered above the United States, and lightning was at least 150 miles away, said Greg Forbes, severe-weather expert for the Weather Channel.
That's a meaningless statement. The US Midwest is
also a region of the world that generates highly intense storms, arguably just as bad as the ITCZ. It does NOT require the world's worst thunderstorm to kill an airplane, even a big one like an Airbus. An
average thunderstorm over the Midwest or ITCZ has the potential to down an airliner, that's why jets fly
around the worst centers of activity, they don't go
through them.
Forbes said an examination of weather data for Sunday, including satellite images, indicated updrafts of perhaps 20 mph, far from the initial reports of 100 mph.
"I wouldn't expect it to be enough to break apart the plane," Forbes said.
Satellite weather and radar can NOT detect turbulence, only conditions more or less likely to produce it. You can't look at the weather records from last Monday and say definitively "Ah,
there is calm air,
there is turbulence. Believe me, pilots and aviation types wish we
could do that, but we can't. Turbulence is
reported by pilots flying through a region.
Though experts generally agreed Thursday that weather alone did not explain the crash, USC aviation safety expert Michael Barr said the investigation was still wide open.
Weather may not be the whole of the reason, but it was almost certainly a major factor.
The sequence started with an autopilot failure
Again, I have to question whether it was a
failure or the autopilot disengaging
as it was designed to do.
... and a loss of the air data inertial reference unit, a system of gyroscopes and electronics that provides information on speed, direction and position. That system has been involved in two previous incidents that caused Airbus jetliners to plunge out of control, though the pilots were able to recover.
Define "plunge out of control". Lose a thousand feet of altitude? A 20 degree bank? What? Yes, a malfunction is serious, but it's not necessarily a near-death experience (unless you're flying though weather severe enough to complicate recovery....). The media tends to be alarmist, it's what sells cornflakes.
The automated messages then indicate that a fault occurred in one of the computers for the major control surfaces on the rear of the plane. Such a failure would have compounded the problems, particularly if the pilots were flying through even moderate turbulence.
OK, if the controls for the tail are wonky THAT is, indeed, a serious problem with life or death implications. At what point in the sequence of disaster did this fault occur? Was it as the beginning of that 4 minute data feed, or towards the end when the airplane may have been breaking up?
The last message indicates that multiple failures were occurring, including pressurization of the cabin. Such a message would have reflected either a loss of the plane's pressurization equipment or a breach of the fuselage, resulting in rapid decompression.
Or it could reflect the airplane
breaking up in midair. Such break ups are not unprecedented in thunderstorms.
All of these issues would have made the plane difficult to control.
Um, yeah. Look, that is really why we pay pilots the big bucks (which are not as big as they used to be):
to fly the airplane. Airbuses have been successfully flown and landed without power, and in other cases missing chunks of the airplane, such as major portions of the rudder. Both of those conditions do make the airplane hard to control but not impossible.
Now, that said, there is supposedly a major philosophical difference between Boeing and Airbus - Boeing
always allows the pilot to completely override the computer on their fly-by-wire models, Airbus not so much. That means that
in theory a serious computer fault may be more likely to down an Airbus than a Boeing, but since some really fucked-up Airbuses have managed to land that is a questionable theory.
When cruising at high altitude, a plane must fly within a fairly small window of speed, said Robert Breiling, an aviation safety expert in Florida. If speed drops even slightly, the plane can lose lift. If the speed is too high, it causes instability over the control surfaces.
"Flying a big jetliner at high altitude without autopilot, you have your hands full," Breiling said.
Yes. But the pilots are trained to handle that.
Look, clearly something went very wrong here. Probably multiple somethings. Even if there was a software glitch, if they had been in calm air it probably would have been recoverable, just as other instances of Airbus glitches were recoverable. Yes, flying at high altitude on manual is more work - but pilots are trained to do that so
that alone is not an adequate explanation. Having instruments malfunction is bad. Having them malfunction at night is worse - that
has resulted in crashes before. Having the pitot-static system ice up is another potential problem, and that would play merry hell with the airspeed and altitude indications which could result in a crash if the pilots don't catch the problem in time, and even moderate thunderstorms carry the potential to do that. If something went wrong with their weather detection equipment that might have resulted in them blundering into crap they ordinarily would have avoided.
I think the media are looking for something new to report in a situation where there really isn't anything new today. I also think they tend to look for a single cause when most aviation accidents have
multiple causes. If a member of an accident board such as the NTSB or the French equivalent stands up on record and says "the weather was trifling, it was a software error that killed the airplane and passengers" then I will give it some credence but really, who are these "experts" and what are their credentials? The gentleman quoted in the article as a "engineer and pilot" - what
sort of pilot? A GA pilot like me, or does he have actual time in an Airbus? My ability to discuss the operations of a passenger airliner is severely limited, the guys I know who fly for the airlines are
much more authoritative even if we are all pilots. How edited are the experts statements by the reporters? Please read objectively and remember most reporters know shit about aviation.
Have a day.
