I am sorry about the Joke QRH checklist, I should have removed it before posting on this topic, as it was getting old anyway.

Folks, let's not forget, its much easier to analyze this scenario from the comfort of our seats in a nice and calm environment, especially now that we know what went wrong!I agree, there were mistakes made by the crew but as a human being we are much more prone to making mistakes in a stress situation than when we are calm and have time to think (and our lives don't depend on it)Also, we (readers) don't have all the information available...Things like:- did the QRH contain pitch and thrust values?- what was the weather like? Nice sunny VMC or night IMC?- was a loss of static/pitot information practised in the sim?Unfortunately, some training facilities train to the legal minimum, not including technical details such as "where does the info actually come from". This type of training is getting more and more important (as someone already mentioned above) and not everyone is in the loop.It is pretty evident that this crew was having extreme difficulties with this as for example they didn't know that the altitude the controller sees comes from the left ADC normally. (The same as the captain sees)While on a nice sunny day in VMC conditions you can pretty well judge your altitue and can definetely see if you're at 10000 ft or at 200 ft, it is sometimes impossible at night, even in VMC! Especially the ocean can be impossible to see as there are no lights and hardly any contrast.And if you're in IMC then its obvious you have no chance of making it visually.I agree that the scenario is recoverable as long as you knowa) what has gone wrong:( what gauges are actually telling the truthc) how to determine the missing informationRegarding a) you have to remember why you get all those warnings and where the warnings get their information. While the overspeed is only speed dependant, the stall warning (stick shaker) doesn't care about speed - it checks the angle of attack. So that was actually a genuine warning. The rudder and mach trim warnings came because of the excessive speed indicated. Nothing actually wrong with these systems.Regarding :( as the crew already figured out, the horizon, track and heading information were still working properly. A source for speed information would have either been the ATC groundspeed readout or the IRS GS readout. Both should show the same as they are not pitot/static dependant.Regarding c) the missing information would be: vertical speed and altitude. While VS is a nice thing to have, it is not as important as altitude. To determine altitude you'd have a few possibilites:-below 2500 ft AGL you can use the radio altimeter-use the weather radar to determine altitude above ground-depressurize the cabin and check cabin altitude (you would then even have a laggy vertical speed indication) But make sure you're below 10k-fly over a VOR and check DME when above (a very inaccurate measurement)-if GPS equipped, get the GPS sensor data which will display true altUsing these techniques you should be able to fly a precision approach (either a ground controlled approach or an ILS approach) to CAT I minimums.Today crews learn all these techniques at some training facilities. They should be able to handle such a non normal. (and actually do on occasions in the sim)It is a tricky situation as you get a lot of false indications at first which can be misleading. The important thing is not to get tunnel vision and focus on only one possible situation.Without ever thinking about this situation you would have an extremely difficult time handling one. if this was the case on said flight, I don't know. For that we'd need more info.Regards,Mark

Roberto, You can slap me in the back ot the head in proxy for Daryl. I am looking forward to seeing you at Charityflight. LDS will be fired up and ready for you to give her a try.

"While the overspeed is only speed dependant, the stall warning (stick shaker) doesn't care about speed - it checks the angle of attack. So that was actually a genuine warning."Don't know about the 757, Mark, but my 767 notes tell me that the stick shaker is influenced by lots of data from the ADC's.... With such ambiguous air data being displayed in the cockpit, knowing that the stick shaker was influenced by air data certainly wouldn't have helped me in my decision-making process :(I agree wholeheartedly that one of the biggest problems here was recognising which data was valid.I keep hearing talk of "pitch/power tables"... Are they really the cure-it-all for situations like this? I don't even see how you can be certain of your engine power when electronic engine control on many modern aircraft is being affected by the same air data sensors as the instruments. And if you vary your pitch/power by even a fraction of a degree, how can you be certain you aren't slowly speeding up or slowing down? If your plane is telling you that you are both overspeeding and stalling, how would you know this? I keep getting the impression that these tables simply wouldn't provide all the data you needed. You would have to have at least one form of reliable air data to know if you were at least "in the ballpark" (V/S, airspeed or altitude).Also, having airplane systems such as Stab Trim, Rudder Ratio and Elevator Feel systems dependent on air data probably wouldn't have helped them control the aircraft either. Nearly all the visual and tactile data presented to these guys is being distorted in some way. Even sitting back in the comfort of their armchairs and having the benefit of hindsight, I think most folks would have trouble with this one. Cheers.Ian.

From Airdisaster.com:"The aircraft departed Lima's runway 15 at 12:42am local time for a flight to Santiago. Five minutes after takeoff the crew reported problems with their instruments and stated they wanted to return to the airport. During the initial climb, the airspeed and altitude indications were too low. In calm winds, the windshear warning suddenly sounded. The aircraft climbed to 13,000 feet before a return to Lima was initiated. While returning, the captain's airspeed and altitude indications were too high, causing an overspeed warning. At the same time, the co-pilot's airspeed indications were too low, triggering the stick shaker. The aircraft kept descending and impacted the water with the left wing and no.1 engine at a 10

Hey Ian!I agree that the situation would require full concentration, regardless of crew experience.Regarding the pitch/power tables, while they aren't 100% correct they give you enough information to be able to maintain an almost level flight!These tables are quite simple actually. They give you different pitch and power settings for different altitudes and configs. You'd have to have a rough estimate of altitude (say to the nearest 1000 ft) but you can achieve that with one of the techniques I mentioned above.I doubt the N1 readout really depends on the ADC? While I assume the EEC use ADC input to determine max thrust, the actual readout should be the actual N1 rotation speed (well at least as long as the N1 gauge and the pickup works normally, which we are assuming here). So you may not be able to set a thrust setting (EEC overriding you) you could still set the EEC in altn mode and then set thrust directly. Anyhow, the N1 gauge should be telling you the truth. At least to my understanding.Even if you were off by a % of target N1 or pitch, while you won't achieve 0 VS, you will get pretty close to it. At least you should be safe for 10-15 minutes. You would regularly try to guess-timate the altitude and then you'll get a feeling for the required pitch to maintain an alttiude. Remember, priority in such a situation is not to be able to maintain 8032 ft precisely, but to make sure you're not gonna hit the ground (or mountain)You should of course make every effort to avoid any terrain in the nearby (which was precisely what this crew did - fly out to the ocean)Regarding the stick shaker, I always thought the "excessive" (ADC) data was only consultet when flaps were out of up? If I recall correctly, the stick shaker will only check AOA if in a clean config?Or am I mixing something up here?Anyway, a point I was trying to make above has been made by the numerous posts here and on pprune in that correct technical knowledge is an absolute MUST to survive a situation like this! You have to know what to trust and the good ol' saying "trust the thrust" is necessary, but not enough :-)Regards,Mark

Thanks for the info, Mark... Re the pitch/power tables... Are N1's also quoted for aircraft with EPR as their primary parameter? (I was wondering what would happen if the 757 that crashed had P&W or RR engines)."Even if you were off by a % of target N1 or pitch, while you won't achieve 0 VS, you will get pretty close to it. At least you should be safe for 10-15 minutes."I'm still a little confused about this. Is the idea behind the pitch/power tables to maintain constant altitude AND airspeed/mach? Maintaining a particular altitude is one thing, but if you don't know your current airspeed/mach... how do you know if you're overspeeding or stalling (other than bits breaking off the aircraft... or your pitch attitude changing suddenly).Re AOA... I was trying to keep it simple, but for you... I'll have to do a bit more reading... ;-) I know for sure that the 744 has logic which varies depending on flap up/not up....but the 767 may not be the same (I don't have any handy detailed data on the 767 Stall Warning System with me at the moment).Back tomorrow, maybe....Cheers.Ian

Bill!!I can give it a try?? Moi???I am setting my alarm clock as we speak!!See you and the guys next week.Roberto

I'm pretty sure that for EPR controlled engines the values will be in EPR (I'm not sure as I only saw the N1 values).Regarding airspeed, theoretically, when flying level and all things being constant (temperature, pressure altitude etc) a given thrust setting will always maintain a constant airspeed. Exception to this is if you are behind the drag curve - there you first need to accelerate past it but then this theory applies.So if you're flying at 340 kts (Vmo) and you've set thrust for 250 kts, the speed will slowly decay to 250 kts.Regarding the pitch/thrust settings, the speed you'll get will be somewhere between green dot and Vmo/Mmo so that you have a very wide window should you encounter turbulence.Of course these thrust settings aren't there for precision IFR flying :-) Just a ballpark value to keep you alive.Regarding AOA, sorry, wasn't my intention ;-)Maybe someone with more knowledge than me can chime in and tell us how it works?Regards,Mark

P.S. BTW, the AOA signal which is fed to the 767 Stall Warning system from the vanes on the fuselage goes via the ADC's. The ADC actually starts processing the signal before it gets to the Stall Warning system (including the process of converting the analog vane angle signal to a digital signal... which the Stall System needs to see). Irrespective of whether other types of air data have influenced the AOA logic, a faulty ADC might possibly generate stall warnings... It depends on how effective the ADC/Stall Warning systems are in analysing faults. As a pilot, if a lot of your air data instruments became unreliable, what would you think of first?.... A sensor problem? A computer (ADC) problem? An icing problem? Volcanic ash? By the time you've figured it out, you've lost a lot of valuable pitch/power assessing time.

Ian,don't forget that crews don't operate alone. The first reaction would be (should be) to ask the other guy. Then check the stby instruments which aren't fed by anc ADC's. If the other guy's instruments agree with the stby instruments, you most probably have a computer problem or the ports on one side are blocked. Either way, you can simply select a different ADC.If all data is screwed, well then its troubleshooting time.Are the EGT's up the roof then you might have encountered volcanic ash.Is everything else normal, you could assume an air data problem and continue with the drill.Usually air data problems arise during initial climb out or on rotation. If that's when you get the discrepancy, assume the air data problem. Its pretty unlikely that your pitot/static ports will become blocked during cruise...

"Regarding airspeed, theoretically, when flying level and all things being constant (temperature, pressure altitude etc) a given thrust setting will always maintain a constant airspeed. Exception to this is if you are behind the drag curve - there you first need to accelerate past it but then this theory applies."By flying level, what do you mean, Mark? Constant barometric altitude? (If so, this takes us back to a requirement of knowing at least one type of air data).I guess groundspeed would be helpful up to a point (unless you happened to be caught in a jetstream). Let's hope your IRMCP wasn't the only display of GS... It would be a little difficult to fly with one eye on the overhead panel and the other on the main instrument panel :(Sorry, but I'm a little lost when it comes to this sort of stuff.Cheers.Ian

Roberto, and others. Yes! The offer is open to those from this community that come to see the pre-view. There will be three A/C in the simulation area of ACZ. Charityflight Ops will be going on, and most flights are just under two hours or less in duration, so a flight in the third sim using LDS is open. Four of the LDS Beta team will be there answering questions and giving flight support. The Beta we will be using is not finished and the failures will be activated, so get ready for the ride of your life!Here is the schedule http://www.charityflight.com/sched.php . Please book a seat/donate to this worthy cause if you can.

"By flying level, what do you mean, Mark? Constant barometric altitude?"Well plus minus yes. VS will most definetely not be exactly 0, but pretty close to it. Again, the point is that you can safely navigate over a not so "terrainy" area.And again, in theory, you only need a pitch and power setting to be able to maintain a 0 VS condition. As long as air pressure doesn't change, your barometric altitude won't change either.Regards,Mark

One thing not mentioned was the amount of stress the crew were under. Physiology has a huge part to play in this horrific event. The pilot's stress levels must have been over the top. You could see it rising as you read the transcript. It is very sad, to say the least.