Computer-related incidents in commercial aircraft

greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread

http://www.rvs.uni-bielefeld.de/

"EFIS failure main suspect in Crossair crash."

-- Rachel Gibson (rgibson@hotmail.com), February 07, 2000

Answers

Rachel, This was an excellent site, thanks for the link. I am impressed with what I have found thus far, and consider this a major find! I had previously found the computer risks digest site. Y2K was a bust, but computer risks, now that is a worthy subject (FYI, the link to the site you give indicates that no crashes due to computer problems directly at least, to date...)

-- FactFinder (FactFinder@bzn.com), February 07, 2000.

Excellent site Rachel, thanks!

Lots of interesting facts about computer technology in aircraft, which of course the idiot trolls like Cherri will say is impossible because the planes that she worked on in the 60's didn't use any computers.

Also, for Mikey... you could learn a lot by reading some of this too. There is a lot more going on in the aviation world besides just the types of aircraft you claim to have worked on. Your statement that Digital Flight Control Systems have nothing to do with the control surfaces of the aircraft is ludicrous, as proven by this article...

Anomalies in Digital Flight Control Systems (DFCS)

-- Hawk (flyin@high.again), February 07, 2000.


Many thanks, I put this in my favorites.

-- ET (bneville@zebra.net), February 08, 2000.

These articles are full of excellent facts from intelligent professionals who know what they are talking about, unlike the troll posers who think they understand the technology because they were allowed to bolt some parts on with a wrench.

"Pilots have extremely limited direct physical control of A320/21/30/40 aircraft should the flight control computers be unavailable"

"Apart from the flight control on A320/321/330/440s and B777s, there are potentially RISKy computer-based systems on almost all modern transport aircraft"

-- Hawk (flyin@high.again), February 08, 2000.


Hawk, I was perfectly aware of the fly-by-wire systems in certain aircraft such as the F-16 and the Airbus aircraft.

Was such a system involved in the Alaska Air Flight 261 incident? NO!!!!!!!!!! The MD-83 doesn't have fly by wire.

Do such systems process dates? NO!!!!!!!!!!!!!!! And please, spare me the Paula Gordon nonsense about overflowing buffers and non- compliant chips.

Could such systems have problems? YES!!!!!! Would these problems be as the result of incorrect date processing? NO!!!!!!!!!!

Hawk, I have 3 different answers near the end of this thread concerning the Alaska Air incident.

-- Mikey2k (mikey2k@he.wont.eat.it), February 08, 2000.



More snips...

"The system became untestable in that testing for each of the possible time relationships between the computers was impossible. This random time relationship was a major contributor to the flight test anomalies."

Definitely Y2K related!

"All aircraft designed and built within the last 15 years have some computer technology in the cockpit"

-- Hawk (flyin@high.again), February 08, 2000.


A couple of interesting statements that seem to contradict Mikey2k's assertion that MD-80's don't have "fly-by-wire" technology:

http://www.rvs.uni-bielefeld.de/p ublications/Incidents/DOCS/Research/Rvs/Article/Vara-opinions.html
"Another colleague points out that computerisation has been sold on economic grounds - replacing cables and hydraulic systems with copper wires (or, in the future, fiber-optic cables) saves weight. And let us not forget that the introduction of digital computerisation in the cockpit coincided with a board of inquiry report to the FAA that a flight engineer (and thus his salary) was no longer needed (1, p180)."

http://boeing. com/commercial/md-80-90/index.html
"Technology advancements in the MD-80 include aviation's first digital flight guidance system." and,
"Its modern Pratt & Whitney JT8D-200 engines, combined with its efficient aerodynamic design, allow the MD-80 to meet all current noise regulations while producing operating costs among the lowest in commercial aviation. "

BTW Mikey2k, you sound like a raving maniac. How about trying to contribute some facts and a reasoned arguement to disprove Hawk's theory instead of spewing emotional nonsense?

-- Cheering on Hawk (onthe@side.lines), February 08, 2000.


Thanks for the excellent contribution, my cheering friend!

I never said I could prove any of this, it's just one theory out of many possible ones, but look at how irate they get! They obviously have some agenda to try to prevent anyone from finding out any truth about Y2K related failures by spreading disinformation. How funny!

-- Hawk (flyin@high.again), February 08, 2000.


Hawk & his cheering-on flock: thanks for the laughs, guys. Cheering On, I've presented plenty of facts to destroy Hawk's inane theory on this and other threads about the Alaska Air tragedy including links to other articles. If you care to, you can look them up and read them yourself, or you can continue to be deluded by Hawk.

In the end you both will believe what you choose despite the facts.

-- Mikey2k (mikey2k@he.wont.eat.it), February 08, 2000.


Ok, what am I missing? The link brought up a site that was last updated July 16 1999.

-- Kyle (fordtbonly@aol.com), February 08, 2000.


Well, it shows there haven't been any computer problems up to July 16, 1999.

-- see here (see@see.com), February 08, 2000.

Hawk wrote: "The system became untestable in that testing for each of the possible time relationships between the computers was impossible. This random time relationship was a major contributor to the flight test anomalies."

Definitely Y2K related!

How do you figure that? The article is describing tests and events that happened long before Y2K so how could it be related? Also, the "time" they are talking about is relative timing between triple modular redundant (TMR) systems. These are not absolute calendar times so they don't care about years, centuries, leap days, etc. You are barking up the wrong tree if you think this supports your so called theory.

-- My Full Name (My@email.address), February 08, 2000.


Hawk,

I received an email from a relative that works
on the electronics on these aircraft. He said
that there are no chips in the servo motors on
the MD80's. He didn't answer my question about
where the motor gets its timed pulse though.

-- spider (spider0@usa.net), February 08, 2000.


Sounds like your "relative" is just covering his butt.

-- (jeffDD@ticon.net), February 08, 2000.

Give Hawk a set of paper wings and let him imagine that he can fly like a bird. Your going to feel awfully silly when this is all brought to light! Go buy Revelle's model of the MD-80 and put it together yourself and then you'll know what you're talking about.

-- Liberal Hater (liberty@bell.com), February 08, 2000.


This was posted by Ed on his other private forum, a letter forwarded to him. I'm taking the liberty to repost it here, hoping I'm not braking rules of privacy, in the spirit of adding clues/insights to this flight #261 crash puzzle. My belief is that no stone should be left unturned, and just because one is an "expert", one can still overlook things and make mistakes, as evidenced by the Y2K debacle itself in the first place (hint to all pilots and aviaonics experts.)

P.S. to Mikey2k and everyone: Adding reference links to previous threads where this has been discussed and "facts" have been advanced would help greatly to cut down on the confusion and chaos, and keeping the discussion under one thread only would make even more sense. [begin cut/paste]

Hi Byron Acohido:

I got your name from an article you wrote about the tail integrity of Flight 261 and saw you are an investigative reporter.

http://www.seattletimes.com/news/nation-world/html98/plan_20000201.htm l

Given that, I want to present what I consider some interesting evidence, all circumstantial, about the crash that you may want to pursue, namely that there is a Y2K problem with the MD-80 series. As far as I know, and oddly so, I have not seen anyone yet propose the Y2K theory for this tragedy.

The information I'm going to present is entirely based on conjecture as I have no other information about the crash than what I see in the news reports. I have no prior or current affiliation with Boeing or MD and have never worked on planes. I am also copying Ed Yourdon (Software and Y2K expert) as he may have some insight into what I have to say.

I think there is now enough evidence to make the following claim reasonable. I believe that the crash was a result of a Y2K problem with the plane's digital controller. Before you dismiss me as a scaremonger, I am a software engineer at an Internet firm and I headed up the Y2K efforts of our software systems at Saltmine. In the course of this process I became very adept and spotting potential Y2K problems or causes. I have also worked with hydraulic systems on boats and understand some of the hydraulic/mechanical issues that the plane could have experienced.

Here is the reasoning. You can accept it or reject it, but please give it some consideration:

1. In the words of a Boeing web site:

"Technology advancements in the MD-80 include aviation's first digital flight guidance system."

I don't know if this means that flight control surfaces are always under electronic control (i.e. fly-by-wire) or only when the autopilot is on, but in either case the plane is flown using electronic means at certain times, which means that the plane's control surfaces can change based on computer calculations.

http://www.boeing.com/commercial/md-80-90/index.html

2. The problem occurred with the Alaska Jet within minutes of 4:00pm PST January 31st 2000. So what, you say? Planes are configured to use what I believe is called 'Zulu' time, another term for GMT, or Greenwich time. This is because they need a reference point that stays constant when flying across time zones. It turns out that GMT = PST+8, so 4pm PST is midnight GMT or 0:00 in the plane's computer. Not only that, but in this case it also coincided with the "month rollover": 1/31/00 to 2/1/00.

It is conceivable that a software system on the plane may have been using the current (within seconds) date/time to help in navigation. If the software had a bug when doing a difference calculation between one month and the next then the resulting output could be bogus. Alternatively, someone may have patched specific lines of code in the software that only execute when the month becomes Feb 2000 - this is conceivable given that some programmers originally failed to account for the fact that Feb 2000 is a leap year. This code may never have been tested and may have crashed the software the moment it was input a date in Feb 2000 for the first time. It is also worth noting that most MD-80s were probably grounded during the Jan 2000 rollover, so this problem, if it also existed then, may never have been noticed during the first Y2K rollover event.

So how would a stabilizer jam? Simplifying greatly - A calculation is made in the autopilot that states where the plane should go in terms of heading angle is derived from the direction of flight, current date/time, and current (GPS, beacon or inertial) position. This value is then passed on to setting an angle for the stabilizer so that the plane is always moving towards its destination. If the date/time calculation fails because of a bug when the date reaches Feb 2000 the resulting number output could be anything; it may even be a number so large that when it finally is processed to set an angle for the stabilizer, the angle could be 90 degrees - something the stabilizer cannot reach, but it can certainly try and make it as close to 90 degrees as possible, which would probably be full extension of the stabilizer. The unexpected quick movement of the stabilizer to reach this extreme position could slam into mechanical stops and dislodge pipes, brackets or whatever, resulting in a mechanical jam that the pilots would be unable to deal with.

Here are specifics from MSNBC web site about the timing of the original problem:

http://www.msnbc.com/news/364560.asp

"At 3:55 p.m. PT, the plane, en route from Puerto Vallarta, was cleared to fly to San Francisco; it was the last routine transmission before the pilots indicated there was any problem.

At 4:10, the pilots acknowledged they were having difficulties and descended to 26,000 feet. A few seconds later, the flight descended to 23,750 feet and the pilots said they were having problems controlling the aircraft"

3. There have now been three planes with this problem, one has crashed and two have landed safely. News reports on the other two that had the problem:

Feb 2: http://www.msnbc.com/local/king/508850.asp

Feb 5: http://www.msnbc.com/news/364560.asp

When was the last time three planes all of the same make had essentially the same control surface problem within five days of each other and never before in their histories? The only two possibilities that I can come up with are identical faulty maintenance procedures or Y2K - the 4:00pm failure pushes me into thinking that this is a Y2K problem. Another oddity is that all three planes were on the west coast (California, Arizona, Reno) when they had the problem - maybe the software calculations fail if the date is greater than Feb 2000 and within a certain longitude window.

4. An MD-80 was known to have crashed years ago in China under the control of its autopilot - it landed short of the runway. This says that the autopilot can be a cause of a crash. In any case, if my theory is correct, you should see the FAA ground all MD-80s very shortly or at least prevent them from flying on the West Coast.

I haven't presented this info to the NTSB since I don't know how to contact them, but I wouldn't be surprised if they are considering this angle also. At the minimum, I hope you found my email interesting and at the best, I hope that quick action is taken by the appropriate parties to prevent further loss of life.

thanks,

Roman Mach

[end cut/paste]



-- Cheering on Hawk (onthe@side.lines), February 08, 2000.


Thanks again friend! :-)

I'm glad to see that other intelligent people have not dismissed this possibility just because the ignorant trolls are trying to snuff it out and the media is trying to cover it up. It is more likely the cause than any of the other bogus explanations I've heard, especially from the moron retarded trolls.

-- Hawk (flyin@high.again), February 08, 2000.


Mikey2K, Based on discussions on earlier threads, I am quite confidence in your knowledge regarding aircraft susceptability to Y2K problem. I appreciate your factual contributions, which mirror the information I have read on industry sites such as Boeing's. I thought you might find this site interesting (as I did) for its discussions of computer risks (general, not y2K) in regards to aviation.

Best Wishes,

-- FactFinder (david@bzn.com), February 08, 2000.


Utterley fascinating.

Jest a Dumb Ole Pilot Who sez:

"You raise the blade, you make the change, you re-arrange me til I'm sane"

-- jestadumb (old@pilot.com), February 08, 2000.


FactFinder, thanks for the good words. Yes, I did peruse the web site and did find it of interest.

Unfortunately, Hawk has misused and misinterpreted the information there to support his inane theories -- well now it's moved past theory to absolute fact for him.

Facts are necessary to make real-life decisions. But sometimes a little silliness is needed to break break the tension. Hawk is quite useful that way -- I've had a few good laughs reading his nonsense.

-- Mikey2k (mikey2k@he.wont.eat.it), February 08, 2000.


That letter was sent to a reporter in Seattle? ROFLMAO, they are probably laughing their butts off too. It's easy for them to contact Boeing and find out that the letter is so mixed up and confused and senseless. I doubt if an answer is in the works, if it is then the answer is predictable. The letter was clearly written by someone with no knowledge of aircraft. Why all of the sudden are people trying to act like they know things like how aircraft work without even bothering to "learn" it? This is not IT or internet technology, it take brains and time and WORK to learn things like aircraft technology. Maybe this generation is so used to getting information on everything and do not realise what it really takes to understand real technology. Oh well, at least the letter will be a warning to the Times letting them know there is still a bunch of hype about Y2K out there.

-- Cherri (sams@brigadoon.com), February 09, 2000.

Cherri, I also think that it's a good thing that the writer doesn't know how to contact the NTSB, the last thing they need is some guy running up to the scene wearing a tinfoil hat yelling Y2K! Y2K!

-- FactFinder (FactFinder@bzn.com), February 09, 2000.

Moderation questions? read the FAQ