Feb 10, 2009

Slander Bus!

I recently received a forwarded email in which supposedly knowledgeable pilots try to blame the Hudson River Ditching on Airbus technology. The email descends into a lot of paranoia and slander against a fine aircraft and I'm surprised that some of these myths fables and lies are still bouncing around in email junk land.

So, I have to take a few paragraphs to respond to some of this mis-information:

++++++++++++++++++++++++++++++++

I got this from ... a buddy of mine, a retired SouthWest Airlines pilot.


Don't be surprised if the Airbus fly by wire computers didn't put
a perfectly good airplane in the water. In an older generation airplane
l
ike the 727 or 737-300/400, the throttles are hooked to the fuel controllers
on the engine by a steel throttle cable just like a TBM or a Comanche.


All it would take is for bird guts to
plug a pressure sensor or knock the pitot probe off or plug it and the
co
mputers would roll the engines back to idle thinking they were over
boosti
ng because the computers were getting bad data.


First, it is unprofessional in the extreme to be speculating about the exact sequence of the engine failures before any data has been released by the NTSB.

Second, older generation engines are also controlled by a (mainly) analogue computer called a Fuel Control Unit (FCU). The FCU input signals from the pilot are transmitted by long steel cables passing through pulleys and convaluted raceways. There are hundreds of documented cases where these mechanical systems have failed for one reason and another. One that comes to mind involved water leaking from the galley which formed into ice on a pulley resulting in loss of control of the engine thrust.

Third, all newer generation turbo-fan engines are more suseptible to bird strikes because of the large fan inlet area. This is true of American Pratt & Whitney engines as well as the CFM engines. The A320 uses both types and I don't know which were installed on Captain Sulley's airplane. The engines don't "care" which airframe they are tied to, although there is some evidence which suggests that fuselage-mounted engines are less likely to encounter birds in the first place.

And Fourth - even the older generation jet engines will shut down if a key sensor is plugged or damaged and sending bad "data" to the FCU.

No pilot, no matter how hard he tries, can turn an A-320 upside down.
It just won't do it. ... I can turn the B777 upside down.


First - no pilot in his right mind would turn an airliner full of passengers on its back! I challenge anyone to cite me a single airliner incident where this would have done anything but make a bad situation worse. In fact more accidents are caused by disoriented pilots than by aircraft failures.

Second - that statement is just plain wrong. The A320 simulator rolls very nicely - I have no intention of duplicating that in an actual aircraft. Any Airbus pilot knows exactly how to over-ride the flight envelope protection. Which makes me wonder about the credentials of the writer.

Google the Airbus A320 Crash at the Paris Airshow in 1998.
Watch the video of an airbus A320 crash into a

forest because the computers wouldn't allow a power increase following a
l
ow pass. The computers wouldn't allow a power increase because they
deter
mined that the airspeed was too low for the increase requested so the
comp
uters didn't give them any.

This is total misinformation (sometimes known as a lie).

First, the engines of that aircraft had slowed down to what is called "Ground Idle" due to the extremely low altitude to which this pilot descended - with a full load of passengers on board! A criminal act of poor airmanship in the first place. Any jet engine, when spooled down to this low idle setting will require several seconds to return to full thrust when the thrust levers are advanced. These engines did respond within the certified time frame, but by then the aircraft was in the trees.

Second, the fact that only two passengers were killed in that accident is largely attributable to the Airbus flight envelope protection system that kept the wings level and the airspeed at the point of maximum lift/ minimum speed as it plowed to a stop. The true information of that accident is probably available online for anyone who cares to find out more.

Please BEWARE of those who would advance their political and economic agendas at the expense of truth.

8 comments:

Aviatrix said...

Thanks. There's a lot of ammunition flying around in the Airbus vs. Boeing wars, but people rarely give the allegations the CSI treatment.

david said...

I claim no experience flying an Airbus or any other turbine aircraft, so I'm just citing secondary sources.

When you cut through the bluster on both sides, it does look like Airbus (like any manufacturer) has sometimes made design decisions that contributed to accidents.

For example, the Paris Airshow crash isn't an open-and-shut case. Shortly before the accident, Airbus did put out an OEB stating that the throttles might not respond to input at very low altitude:

http://en.wikipedia.org/wiki/Air_France_Flight_296

Here's a different accident where an Airbus design flaw -- no alarm for partial autopilot disconnect -- was definitely one link in the accident chain:

http://en.wikipedia.org/wiki/Aeroflot_Flight_593

Neither of these is a slam-dunk against fly-by-wire, of course, and neither has any link to the Hudson incident.

Greybeard said...

Thanks for the discussion here. You're addressing some of the questions I myself have asked.
And thanks David for your input. When I read,
-First, the engines of that aircraft had slowed down to what is called "Ground Idle" due to the extremely low altitude to which this pilot descended - with a full load of passengers on board!-

Two points here...
Why did the engines "slow down"?
The accusations I have heard are that the aircraft computers did the slowing, not the pilot. And when the pilot tried to bring the power back, the computer worked against, rather than with him. Isn't that basically what the email says?

Secondly, the aforementioned crash was at an airshow, right? Educate me...
Why would an airliner full of passengers be making a low pass at an airshow?
Could it be that the airplane was full of Airbus employees and their guests, and they were fully aware of what was about to happen? Making a low pass at an airshow?
Who could have imagined?

I'm no expert on things with a wing that doesn't move, so I'll be reading discussion about this incident, here and elsewhere, with interest. But at this point, to this outsider, there surely appears to be a fire somewhere beneath all the smoke.

Anonymous said...

I can't help but think this guy hasn't a clue... besides, the A320 incident he speaks of occurred in 1988, not 1998.

Aluwings said...

My point isn't to say that the Airbus is perfect. But the over-riding "gist" of the email was a one-sided slam I needed to respond to.

In the end it is the pilot's responsibility to know the aircraft's limitations and fly within them. And at the same time it is never acceptable to put your passengers at risk.

More in the next post.

Frenchie said...

I'm a long time reader but first time commenter. I just want to say thanks for this post :), it's nice to have someone who truly knows the type challenge some of the misinformation that's out there.

I will admit to having the 737 as a favorite type. That said, I still think the A320 (or any aircraft for that matter) is a beautiful machine. I fully understand why pilots and passengers love it.

As a passenger I feel just as safe whatever I'm flying in - whether it be Boeing, Airbus, Fokker or anything else for that matter.

I trust the technical ability of the engineers who designed the bird but more importantly I trust the pilots and their abilities.

Splendor said...

Thanks for posting this. Being a rather new Airbus driver myself I still marvel at the technology inside this amazing aeroplane ...

David: I have no idea how the A310 works, but on the 320 or newer any degradation of autopilot state makes a loud, annoying noise.

S.

Jeff said...

The A320 crash in France was not at Paris airshow, but a little airshow in Habsheim (a short airfield) near mulhouse.
The flight departed from Paris as scheduled flight, landed in strasbourg (or mulhouse didn't remember) and departed with passengers invited and some officials (mayors, deputy etc) for a low pass on the show. The aircraft was in service for 2 monthes.

The crew didn't made a good flight preparation (they were using black and white copies of VFR charts, and didn't see that a forest was behind the field. They thought the airfield was in plate area.
They used same altimeter setting than in departure airport (or the elevations were not the sames).

The crew thought being at 300 feet, but they were below 100, so the aircraft came in landing phase.
The throttles were in idle, but not in flight idle, in ground idle (cause below 100 feet).
They didn't hear the RA call because in this aircraft (one of the first A320 - 100), this call didn't come through the headset, only through speakers.
When he see the forest, captain engaged TOGA but engines didn't react (ground idle remember, so less reactivity), so he "recycles" thrust levers (TOGA - IDLE - TOGA).
Less of time.

All of investigators accorded to say this accident wouldn't happened with another aircraft because in this case, the pilot had too much confidence in his aircraft but didn't know very well the limitations of possibilities.

I'm not a airline professionnal, just a PPL fan of Airbus aircrafts who "studies" the A320 for 5 years.

For frenchspeaking guys, the captain of this flight is posting on a french website called www.rcoco.com (don't remember his username).

For all boeing antiairbus guys who claims that airbus is full of perversations and who change modes without advertising pilots, I invite them to read some reports of the following incidents / accidents

In 1992, a B744 of AirFrance left runway on landing at Tahiti Faa after the aircraft entered in goaround mode while the captain was trying to land. He overforced the thrust levers, but upon touchdown, THR1 went FULL FORWARD while 2 - 3 - 4 went IDLE REVERSE. 90 degrees turn into the Lagon

A lockheed tristar crashed near Miami while the crew was trying to reset the landing gear light. One of them pushed inadvertently on the yoke, disengaging PA, and aircraft crashed.

744 of China Airlines who loss 20.000 feets near SFO after an engine flameout and incapability of the crew to maintain the yaw resulting in assymetrically stall. (wouldn't have happened with an airbus, would it ?)

THanks for reading it ;)

(sorry for the mistakes in my sentences, but it's an english comment from a french guy) ;)