 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion Groups General AviationLearningIFRHomebuiltSoaringUltralightRotary-wingCountry Specific Australian GroupUK GroupRelated Topics BoatsCarsMotorcyclesMore Topics ... |
Aviation Forum / Country Specific / Australian Group / December 2003SQ286 tail strike AKL March 2003 - TAIC Report
Here's the official abstract http://www.taic.org.nz/aviation/abstracts-a-00.html#03-003 "Boeing 747-412 9V-SMT, flight SQ286, tail strike during take-off, Auckland International Airport, 12 March 2003 On Wednesday 12 March 2003, at 1547, flight SQ286, a Boeing 747-412 registered 9V-SMT, started its take-off at Auckland International Airport for a direct 9-hour flight to Singapore. On board were 369 passengers, 17 cabin crew and 3 pilots. When the captain rotated the aeroplane for lift-off the tail struck the runway and scraped for some 490 metres until the aeroplane became airborne. The tail strike occurred because the rotation speed was 33 knots less than the 163 knots required for the aeroplane weight. The rotation speed had been mistakenly calculated for an aeroplane weighing 100 tonnes less than the actual weight of 9V-SMT. A take-off weight transcription error, which remained undetected, led to the miscalculation of the take-off data, which in turn resulted in a low thrust setting and excessively slow take-off reference speeds. The system defences did not ensure the errors were detected, and the aeroplane flight management system itself did not provide a final defence against mismatched information being programmed into it. During the take-off the aeroplane moved close to the runway edge and the pilots did not respond correctly to a stall warning. Had the aeroplane moved off the runway or stalled a more serious accident could have occurred. The aeroplane take-off performance was degraded by the inappropriately low thrust and reference speed settings, which compromised the ability of the aeroplane to cope with an engine failure and hence compromised the safety of the aeroplane and its occupants. Safety recommendations addressing operating procedures and training were made to the operator, and a recommendation concerning the flight management system was made to the aeroplane manufacturer." Full report (3,839 kB pdf file) http://www.taic.org.nz/aviation/03-003.pdf Newspaper report http://www.nzherald.co.nz/storydisplay.cfm?storyID=3539645 "A series of basic pilot errors led to a Singapore Airlines 747 dragging its tail about 500m along an Auckland Airport runway in March this year, a damning safety investigation has found. The aircraft, flight SQ286 to Singapore, was forced to circle the airport on March 12 for about 20 minutes before making an emergency landing. None of the 369 passengers, 17 cabin crew, or three pilots was injured in the accident, but the tail of the plane was extensively damaged. ..." have a safe flight... Errol Cavit A question . If a plane starts scraping its tail along can the pilot not place the wheels back on the deck and stop ? Or is it to late ? If he had 500 mtrs of drag is that not to late to do something ? Cheers Phil >A question . > >If a plane starts scraping its tail along can the pilot not place the wheels >back on the deck and stop ? Going to depend. The problem is most of the time this happens, the aircraft is well past V1, consequently, there may not be enough runway to stop. >Or is it to late ? If he had 500 mtrs of drag is that not to late to do >something ? The real question is why he didn't realize there was a problem when the aircraft refused to depart the runway. Normally on a 747, once you reach Vr, when you pull back, the nose rises and the aircraft almost instantly departs the runway. If the nose comes up, but the aircraft does't depart the runway, almost by definition, something is seriously wrong. >Cheers Phil > >--- >Outgoing mail is certified Virus Free. >Checked by AVG anti-virus system (http://www.grisoft.com). >Version: 6.0.545 / Virus Database: 339 - Release Date: 27/11/2003 > >A question . > > [quoted text clipped - 12 lines] > aircraft does't depart the runway, almost by definition, something is > seriously wrong. Thanks Matt Could you please tell me how long would it take to stop the beast from when the cab driver would have thought oh sh.t . If the tail draged for 500mtrs would that have been enough ? >> >A question . >> > [quoted text clipped - 7 lines] >> >Or is it to late ? If he had 500 mtrs of drag is that not to late to do >> >something ? The something you do is firewall the engines. In this case I think the aircraft was making about 165kt when it finally departed the runway. Without knowing the actaul TOW and Power settings, it is hard to know just how much runway was chewed up, but it was probably substantial, and I wouldn't want to bet on there being enough to stop at that point. Based upon 165kt That is about 280 feet per second. If he is lucky, it will take about 17.4 seconds to stop. (1/2 g) 17.4 * 17.4 *16 *.5 (1/2 at^2) about 2400 feet. However in order to do that, there are a couple things that have to happen quickly, because each second you think about, another 280 feet has gone by, and you have chewed up a heft bit of runway because of the low power settings, and tail dragging. The big one is getting reverse thrust engaged, and the speed brakes at. At 165kt, there isn't going to be a lot of weight on the gear, and that will seriously restrict braking until there is a lot of weight on the gear, hence the need to deploy the reversers and speed brake. As JB has pointed out, the actual reverse thrust isn't all that much, but it does very effective kill both the lift from the wing, and the forward thrust, which even when idling is significant. > Could you please tell me how long would it take to stop the beast from when >the cab driver would have thought oh sh.t . If the tail draged for 500mtrs [quoted text clipped - 4 lines] >Checked by AVG anti-virus system (http://www.grisoft.com). >Version: 6.0.545 / Virus Database: 339 - Release Date: 27/11/2003 Almost certainly way past any chance of refusing the takeoff, and for lots of reasons that's probably a really bad idea. The engines should have been firewalled, and the aircraft derotatated to get the tail off the runway. Only a degree would be enough. My understanding of the event is that the engines were never pushed up, and that the amount of aft stick was increased, but I haven't yet read the report, and that info is 2nd hand from an expat Singair Captain. JB > >> >A question . > >> > [quoted text clipped - 43 lines] > >Checked by AVG anti-virus system (http://www.grisoft.com). > >Version: 6.0.545 / Virus Database: 339 - Release Date: 27/11/2003 Only a few (very few) knots from disaster. It actually took off - just - in ground effect, 5 knots below stall speed out of ground effect. If it had not accelerated those 5 plus a couple whilst still in ground effect ................ "Report 03-003 Page 16 2.16 During the take-off, the aeroplane would have accelerated more slowly than it should have because of the low thrust setting for its weight. When the captain rotated the aeroplane at the recorded VR he applied a correct rotation rate but the airspeed was far too slow for the weight of the aeroplane, and some 19 kt below its stalling speed. Consequently, the aeroplane remained on the runway and pivoted around its undercarriage to a body angle that exceeded the geometric limits to prevent a tail strike. In this nose high attitude with the aeroplane still on the runway, induced drag will have increased significantly, thus further reducing the aeroplane.s acceleration. With the friction from the tail scraping along the runway, drag would have increased further. The FDR showed that the aeroplane accelerated only some 14 kt over 490 m after the rotation. Consequently, with the low thrust and increased drag the aeroplane would have used more runway than normal. In this case there was still about 1160 m of runway remaining." MY COMMENT: In other words, at lift off, it was 19 - 14 = 5 knots slower than stall speed out of ground effect. "2.18 When the aeroplane became airborne it did so in ground effect and in a near stalled state because it began to lift-off at about the stalling speed. The captain did not increase thrust in response to the stick shaker because he thought it was a spurious warning, which went away after the nose was pitched down. Also he said when he checked the airspeed it was normal in relation to the V speeds on the speed tape. However, the stick shaker was a proper warning of an impending stall and had activated for some 6 seconds. The captain would have been prudent to have treated the stick shaker as a real stall warning and increased thrust in accordance with his training and standard procedures. Shortly after the aeroplane became airborne, because of a slow airspeed that was only a few knots above the stalling speed, there was the potential for a loss of control. The first officer should have verified maximum thrust, and the third pilot could also have advised the captain to increase thrust, being an opportunity for them to have exercised good CRM. " >From the report: "The first officer should have verified maximum thrust, and the third pilot could also have advised the captain to increase thrust, being an opportunity for them to have exercised good CRM. The crew details. 1.5.1 The aeroplane crew consisted of a captain, a first officer, a second first officer and 17 cabin crew. 1.5.2 The captain was aged 49. He held an Airline Transport Pilot Licence, and his associated medical certificate was valid until 30 April 2003. He had flown some 12,475 hours, including 54 hours on the Boeing 747-400 type after his type conversion. 1.5.10 The first officer was aged 34. He held a Commercial Pilot Licence, and his associated medical certificate was valid until 31 January 2004. He had passed the Airline Transport Pilot Licence examinations and tests, but had yet to attain the necessary flying hours before being issued such a licence. There was no restriction on him performing his duties with a commercial licence. He had flown some 1,309 hours, including 223 hours on the Boeing 747-400 type, which met the operator's requirements to be experienced on type. 1.5.15 The third pilot, who was a first officer, was aged 38. He held an Airline Transport Pilot Licence, and his associated medical certificate was valid until 30 September 2003. He had flown some 6,302 hours, including 3,386 hours on the Boeing 747-400 type. 2.3 Although the captain was well experienced he had only recently converted to the Boeing 747-400 from Airbus and completed his command training. Consequently, the operator considered him to have low experience on type and he had to be paired with an experienced Boeing 747-400 first officer. Although the first officer was qualified and considered experienced on type, he was a relatively inexperienced pilot with a commercial licence and some 1309 flying hours. He had flown some 223 hours on type. However, the third pilot was a qualified and very experienced first officer, having flown some 3386 hours on type. MY COMMENT: So the third pilot was by far the most experienced on type on the flight deck, and he obviously would have known the Captain was new and the FO was junior, even though "considered experienced". Even though he had no formal role, it appears he must have been totally switched off mentally during the whole pre flight checking of the weights, setting the bugs, everything. Even if he wasn't "working" surely his sub-conscious brain should have "sussed" - I am here - because it is a long trip - we should be heavy - we should be fast - why are all the speeds so low ? - ie, that it didn't add up ? > MY COMMENT: > So the third pilot was by far the most experienced on type on the flight deck, and he obviously [quoted text clipped - 4 lines] > trip - we should be heavy - we should be fast - why are all the speeds so low ? - ie, that it > didn't add up ? But you're talking about a culture here where one does not question the man in charge...the Captain. CRM doesn't work in that situation. TF > > MY COMMENT: > > So the third pilot was by far the most experienced on type on the flight [quoted text clipped - 16 lines] > > TF Perhaps you have a point, I don't know. Looking at the hours they all had on type, it is a worry. For a start, there is no mention of any FO time on type for the Capt. I suppose culture wise, if you are correct, once a captain, always a captain, never revert to FO on a new type ? It is a worry that various nations and operators have widely different requirements for experience levels, and even worse, nobody knows what they are. I wonder how many of the pax would be happy if they knew that their neck was in the hands of a guy with (apparently) only 54 hours on type - period. I also wonder if airlines doing code share operations consider such matters. If I bought a QF ticket, and if I did so because it was QF, (reputation etc being a factor), and then found out I was on a code share with operator X, which turned out to my 747 driven by a 54 hr capt and a 223 hr FO's, I have to say, I would be mighty pissed off. This sort of thing should not be allowed to happen. It has to be fixed. The ICAO should be made to put their foot down - HARD - regardless of how much cultural, national, or diplomatic trouble it generates. PC > If I bought a QF ticket, and if I did so because it was QF, > (reputation etc being a factor), and then found out I was on a code > share with operator X, which turned out to my 747 driven by a 54 hr > capt and a 223 hr FO's, I have to say, I would be mighty pissed off. I'd turn around and walk right back off the aeroplane if I booked a Qantas flight on a Qantas aircraft and they gave me a codeshare. Singapore Airlines pulled that stunt on me in Korea once, overbooked a flight back to Singapore, and bumped a whole bunch of people off onto Korean Airlines flights. Talk about out of the frying pan and into the fire. Talk about ignorance being bliss too, I had no idea back then just how fundamentally dangerous those two airlines are. > This sort of thing should not be allowed to happen. It has to be > fixed. The ICAO should be made to put their foot down - HARD - > regardless of how much cultural, national, or diplomatic trouble it > generates. There's so much political and business fiddling going on behind the scenes that it's pretty much impossible for the gummint to pull the plug on an airline. If the ATSB (or New Zealand's equivalent) said "Right, SQ is no longer allowed to operate here, 'cos they're not safe" there would be so much screaming and yelling from gummint, and Qantas and AirNZ shareholders ('cos the first thing Singapore would do is "Right, f.ck ya, you can't fly here either") that it would fill the newspapers for a month. They'd have to back down. Singapore would put Oz/NZ back on visa-required status, and they'd knock most of the applications back. At the end of the day, they own the aeroplanes, they can operate them how they damn well please, and the govmints have too much vested interest to 'risk' trying to save a few lives. The *only* thing you can do is tell all your friends, colleagues and contacts. Even so, it's not easy. People get it in their heads that because they've been conditioned to like the advertising, the airline *must* be safe. Trying to tell Joe Punter on the street that Virgin Blue, or Singapore Airlines, or the likes are not safe gets pretty much the same reaction you'd get if you tried to tell them that the sky is green. Bob The *only* thing you can do is tell all your friends, colleagues and contacts. Even so, it's not easy. People get it in their heads that because they've been conditioned to like the advertising, the airline *must* be safe. Trying to tell Joe Punter on the street that Virgin Blue, or Singapore Airlines, or the likes are not safe gets pretty much the same reaction you'd get if you tried to tell them that the sky is green. Bob Lowest common denominator (sorry <enter correct speak mode> - politically and ICAO sanctioned - "worlds best practice" wins again <exit correct speak mode>). Gee, I am starting to feel all warm and fuzzy about NAS-E too. I take it all back Coop, Stealth, and a few others. Note the findings:- 3.2 The pilots were appropriately qualified and fit for the flight. Stunning statement that. Qualifications don't include stick time apparently - oh well. It surprises me that they had the balls to print it anyway, but Bob, well, you did have that smile on your face before you downloaded it didn't you. Unstated "I told you so acknowledged". Enough said. But, they did try just a little to give it a mention - down at point 9. 3.9 The captain's low type-experience level and some negative transfer from another aeroplane type he had recently flown might have contributed to his demonstrated lack of awareness about the performance of the aeroplane. To state the bleeding ................ I Love the use of the word "low" there. I would also love to know what the "negative" from the Airbus was ! Are they implying that the Airbus is more idiot proof, and that he may have been lulled into a false sense of security by previous Airbus experience ? Perhaps the Boeing FMS not challenging his inputs are to the fore here the way Airbus does ? This situation could not have occurred on an Airbus perhaps ? Is that why they are giving Boeing the gee-up ? I know, just thought of it !! All Boeing pilots have to be re-rated when down convrting from Airbus - (by HARS perhaps - no - come to think of it - they mostly fly Lockheed stuff - don't they .... ). In any case, it now appears there may be something new in this after all - it seems you now need a "vintage rating" when converting from high tech to low tech types ! I wonder if that includes spin training ? I am getting too sarcastic here .......... sorry all. 3.12 Because the captain did not respond correctly to an impending stall condition as the aeroplane became airborne, and because the 2 first officers did not exercise good CRM, a loss of control could have occurred. It's a bloody miracle it got up out of ground effect at all. If the numbers are correct, there were only a VERY few seconds between not flyable out of ground effect and flyable out of ground effect. 3.14 The erroneously low thrust used for the take-off prevented the aeroplane from accelerating normally and degraded its take-off performance and safety margins. Repeat above. 3.15 Had the aeroplane moved off the runway, stalled or had an engine failure with its degraded take-off performance, a more serious accident would probably have occurred. That word "probably" is a f.cking cop out. There is no f.cking "probability" about it, other than 100 percent. - If it went into the dirt off the edge, wheel drag would have precluded further acceleration, very probably would have slowed it in fact, let alone yaw, let alone roll too, outcome obvious - no take-off performance - period. - If it stalled, outcome obvious - no take-off performance - period. - If it ad an engine failure, outcome obvious - no take-off performance - period. Notice how in the "Safety Recommendations" section, there are issues regarding systems and crew actions, but not a word about crew qualifications. Boeing is to make the FMS more idiot proof (see above) .......... Hmmmmm .................. I wonder how many journalists have downloaded and read this report, and I wonder how many of them have the brains to understand what they are reading. As for the operators Bob, they only keep flying "their" aeroplanes so long as the pax keep "buying" their tickets. Image and reputation are commercial issues - sure. But so are prangs, they tend to go on the red side of the balance sheet, or do they any more ? Look at all the big ones over the years. How many non-gov backed operators survived back then ? I wonder what would happen today. Doesn't seem to have hurt SQ none, not after Taipei, not after this one. Perhaps people have become so used to transport accidents of all types, that it no longer rates in the mind of most. A train here, a ferry there, a jumbo over yonder. Who cares. Yeah - I give up Bob, you got it in one. > If I bought a QF ticket, and if I did so because it was QF, (reputation etc being a factor), and > then found out I was on a code share with operator X, which turned out to my 747 driven by a 54 hr > capt and a 223 hr FO's, I have to say, I would be mighty pissed off. How do you know it doesn't happen at Qantas. Just where do you expect pilots to get their 'experience'. Fly the simulator around for 12 months. Training courses are recommended by the aircraft manufacturer and approved by each countries' Aviation Authority. The report mentions the Captain had over 6000hrs of command time on A340s, and 12000hrs total. That is a hell of a lot of general flying experience in world wide operations. It would appear that none of the crew used any of their previous experience to avoid getting into trouble, but the Captain did a remarkable job at flying out of it. In a longhaul operation like Singapore Airlines, the most current you will every be is at the end of your training course. > > If I bought a QF ticket, and if I did so because it was QF, (reputation > etc being a factor), and [quoted text clipped - 19 lines] > every be > is at the end of your training course. Not complaining about total time, the issue is stick time on type, and specifically, whether anybody should ever go to command on type without substantial FO stick time on type. > > > If I bought a QF ticket, and if I did so because it was QF, (reputation > > etc being a factor), and [quoted text clipped - 22 lines] > Not complaining about total time, the issue is stick time on type, and specifically, whether anybody > should ever go to command on type without substantial FO stick time on type. As for QF, I may be wrong, but I was under the impression that there was a graded progression, something along the lines of FO73 then FO76 then Command73 then perhaps FO74 then Command76 then some more FO74 before Command74, or something similar. I don't think anybody ever gets command of any QF type without previous FO on type, (at least I bloody well hope not) not to mention sim retraining, re-checkouts etc along the way, obviously, or is that a false assumption too ? The sort of system you're talking about isn't realistically possible, or even necessary. (In fact you could never bring a new type into service if you worked that way). You don't need to be an FO on a 767 (or whatever) before you can be a Captain on it, although you do need both decent training and support. I was never a 767 FO. My training was a combination of a conversion and Command training, and as such was a bit longer that it would have been had I come from the 767 (though only by 4-5 sims and a couple of sectors). The big problem I see in this report is that the FO had only 1300 hours TOTAL. What on earth was he doing in the right hand seat of any jet airliner, much less a 747. The Captain would have been effectively operating single pilot. Nice mix of experience... JB > > > > If I bought a QF ticket, and if I did so because it was QF, (reputation > > > etc being a factor), and [quoted text clipped - 28 lines] > any QF type without previous FO on type, (at least I bloody well hope not) not to mention sim > retraining, re-checkouts etc along the way, obviously, or is that a false assumption too ? A point I've been meaning to ask of the heavy drivers. How much training/experience at low alt go-arounds etc do you get? Low being below 500'. Sim or metal. tnx  SignaturePaul Repacholi 1 Crescent Rd., +61 (08) 9257-1001 Kalamunda. West Australia 6076 comp.os.vms,- The Older, Grumpier Slashdot Raw, Cooked or Well-done, it's all half baked. EPIC, The Architecture of the future, always has been, always will be. > But you're talking about a culture here where one does not question the man > in charge...the Captain. > CRM doesn't work in that situation. But are we told the nationalities of the flight crew? I didn't see them. > > But you're talking about a culture here where one does not question the > man > > in charge...the Captain. > > CRM doesn't work in that situation. > > But are we told the nationalities of the flight crew? I didn't see them. My thoughts exactly - I've heard plenty of different accents from up front when I've flown with them including Oz. Sounds like stereotyping to me - more convincing to bag them on technical evidence if it exists. Last Sunday it was Capt Raj in command of SQ226 who stopped the pushback of 9V-SRK about less than half a plane length from the gate when the the blades in the big round thing hanging under the right wing wouldn't spin properly. So it was back to the gate and into the airconditioned comfort of the departure lounge for 2 hours. I was sitting on the left I couldn't see all the action but the fire-rys got all excited and whizzed over to the Intl terminal with 3 appliances. http://members.iinet.net.au/~eaadams/stuff/SQB777dec0703.JPG Interestingly when we were back on board and about to pushback for the second time, Capt Raj made a point of informing us that the "Qantas" engineers had declared the engine fit for flight. Of course no doubt they were the only engineers available but I don't recall QF operating any aircraft with these big mothers - but I guess Trevor would argue that they get plenty of practice fixing those of SQ and MH :-) Aubrey >> > But you're talking about a culture here where one does not question the >> man >> > in charge...the Captain. >> > CRM doesn't work in that situation. Heh. Like KLM at Tenerife, you mean? :-) > >From the report: > "The first officer should have verified maximum thrust, and the third pilot could also have advised [quoted text clipped - 35 lines] > trip - we should be heavy - we should be fast - why are all the speeds so low ? - ie, that it > didn't add up ? No "feel" for the right answer, perhaps? Read a report of a 737 takeoff from a pacific island where the pressure sensors in the engine were clogged with phosphate goo (on BOTH engines- bit of a flukey event). This gave a spuriously high takeoff power reading. There was another experienced captain in the cockpit "deadheading" who had been invited up for the takeoff. He knew things were not right, and just as he realised it, so did the captain, who "firewalled" the throttles (IAW Boeing recommendations, apparently) and saved the day (just). These guys had a "feel" for what was right, and also went back to first prinicples when they detected an error (ie when in doubt give it full power, and worry about the impact on the engines once off the ground). Maybe there is too much "by the book" aviating.... that people are less able to detect book errors....? Coop >> >From the report: >> "The first officer should have verified maximum thrust, and the third pilot could also have advised [quoted text clipped - 35 lines] >> trip - we should be heavy - we should be fast - why are all the speeds so low ? - ie, that it >> didn't add up ? There are few things you have to wonder about in this affair, you can thumbnail the TOW with reasonable accuracy. OEW on the aircraft is about 400,000 pounds. It is about a 10 hour mission, so about 220,000 pounds of Jet A, figure another 20,000 pounds or so for rervers, unusable etc, and 380 warm bodies is about 80,000 pound. So TOW is not likely to be much below 720,000 pounds, and any number that is far below 720,000 is clearly wrong. The 100 tonne error would have put the TOW at about 500,000 pounds, and even with the aircraft empty, 100,000 pounds of fuel isn't going to get it anywhere near Singapore. In fact it is pretty hard to fly a 747-400 anywhere at that sort of weight. It is doubtful that weight on a 744 flight SYD-MEL would be that low! By the same token, any sort of intuitive feel for the mission, and experience would have suggest that Vr was much lower than anything they were accustomed too. How do you go drag the tail down the runway for 490 meter and not notice that either a) You are dragging the tail, or b) you haven't departed the runway yet. Boeing conducts such tests. They are called minimum unstick speed. Normally in a 747, at Vr, you pull back on the stick, the nose comes up, and the aicraft departs the runway within a second. Between the refusal to depart the runway, and the stick shaker, the light bulb should have come on somewhere that says'' Aircraft Performance problem''. There are two things you do when you realize that, and in fact I was talking a UA 777 F/O who says you don't ever question the stick shaker. If it comes on just after takeoff, the procedure is firewall the power levers, and lower the nose if you can. As long as you don't fly into something, or exceed Vne, the things that can happen to you are nowhere near as bad as what can happen if you ignore it... The last guys who failed to recognized that ended up in the bottom in the Potomac river, called Air Florida flight 90... >No "feel" for the right answer, perhaps? No feel for a lot of right answers in this one... I have a question for the heavy pilots now that you mention it. Being so high up in the cockpit, and so relatively removed from a close ground reference, do you get much of a sensation of speed as you accelerate to flying speed? I imagine the visual cues would be a lot different than when sitting in a plane with your eyes perhaps 6ft off the ground, and being able to see the ground whizz so closely by. I was just wondering if you can "feel" if the speed is right or not, like you can in a light aircraft. I also suppose that these plance take so relatively long to change their acceleration etc, that by the time feel came into it, it could be too late? Regards, Andrew. > MY COMMENT: > So the third pilot was by far the most experienced on type on the flight deck, and he obviously [quoted text clipped - 4 lines] > trip - we should be heavy - we should be fast - why are all the speeds so low ? - ie, that it > didn't add up ? > I have a question for the heavy pilots now that you mention it. > Being so high up in the cockpit, and so relatively removed from a close [quoted text clipped - 8 lines] > > Regards, Andrew. You have a good idea of what looks right... JB Errol Cavit said.... EC> weighing 100 tonnes less than the actual weight of 9V-SMT. A take-off EC> weight transcription error, which remained undetected, led to the EC> miscalculation of the take-off data, which in turn resulted in a low EC> thrust setting and excessively slow take-off reference speeds. The Couldn't he feel the thing scraping, and what about being in such an attitude for so long? How come they didn't pick up on that? Do the procedures rely that much on the numbers that "seat of the pants" flying no longer exists? > Errol Cavit said.... > [quoted text clipped - 8 lines] > Do the procedures rely that much on the numbers that "seat of the pants" > flying no longer exists? Agreed - makes you wonder how diligent the crew are at cross-checking. Surely either pilot should have noticed the low settings and questioned them. When the aircraft did not respond as expected, and they made the decision to fly, then should not TO/GA power have been selected? John > Couldn't he feel the thing scraping, and what about being in such an > attitude for so long? How come they didn't pick up on that? The pilots are a long way away from the scraping but one wonders what was heard and felt back in row 70.... You'd lose a few of your nine lives going through that. Another thought is: so the three guys on the flight deck missed this but shouldn't the flight management computer been able to guess there was something wrong? It should be possible for the computer to be programmed to alert for mistakes like this. It's times like this when you think that perhaps it would be better for a well programmed and tested piece of software be given the job of flying the plane rather than a bunch of, well, humans. James > Another thought is: so the three guys on the flight deck missed > this but > shouldn't the flight management computer been able to guess there was > something wrong? It should be possible for the computer to be > programmed to alert for mistakes like this. I asked the question a few years back: "Does the aeroplane know how heavy it is when it is sitting on it's wheels?". IIRC, it doesn't. I imagine that it wouldn't be a particularly difficult thing to integrate in a new design, just a bunch of load-cells at various points in the gear mounting points. Given that, and a trustworthy GPS, you wouldn't have to tell the machine anything to calculate distances and speeds and set the bugs. (Obviously, you'd tell it your assigned runway, but if you then turned onto something else and gave it go power, it would be able to figure out if you'd done something stupid). Would work wonders for some of these monkeys with more dollars and narcissism (sp?) than cognitive ability. G > > Another thought is: so the three guys on the flight deck missed > > this but [quoted text clipped - 20 lines] > > G And if you did that, you could just imagine if a crew lined up on a wrong runway, or taxiway, as a crew in canada did somewhere once, and they opened the power leavers to go, and the computers said "no way", and locked the brakes and shut off the fuel valves, with a neat big red flashing "Get F..'d !" on all the displays ! > And if you did that, you could just imagine if a crew lined up on a wrong runway, or taxiway, as a > crew in canada did somewhere once, and they opened the power leavers to go, and the computers said > "no way", and locked the brakes and shut off the fuel valves, with a neat big red flashing "Get > F..'d !" on all the displays ! "I'm afraid I can't let you do that, Dave." > And if you did that, you could just imagine if a crew lined up on a > wrong runway, or taxiway, as a crew in canada did somewhere once, and > they opened the power leavers to go, and the computers said "no way", > and locked the brakes and shut off the fuel valves, with a neat big > red flashing "Get F..'d !" on all the displays ! I sure there's a lot of families of victims (and a lot of survivors) of the SQ 747-400 (9V-SPK) stack in Taipei that would like it very very much if the remaining aircraft in the SQ fleet were configured to say exactly that!!! G >> And if you did that, you could just imagine if a crew lined up on a >> wrong runway, or taxiway, as a crew in canada did somewhere once, >> and they opened the power leavers to go, and the computers said "no >> way", and locked the brakes and shut off the fuel valves, with a >> neat big red flashing "Get F..'d !" on all the displays ! > I sure there's a lot of families of victims (and a lot of > survivors) of the SQ 747-400 (9V-SPK) stack in Taipei that would > like it very very much if the remaining aircraft in the SQ fleet > were configured to say exactly that!!! And even sadder to consider that another pilot saw them, and remarked to his other that they where on the wrong runway, but neither picked up the mike and yelled out about it :( SignaturePaul Repacholi 1 Crescent Rd., +61 (08) 9257-1001 Kalamunda. West Australia 6076 comp.os.vms,- The Older, Grumpier Slashdot Raw, Cooked or Well-done, it's all half baked. EPIC, The Architecture of the future, always has been, always will be. > > Another thought is: so the three guys on the flight deck missed > > this but [quoted text clipped - 20 lines] > > G The aircraft doesn't know how heavy it is simply because it has no way of knowing how much cargo and how many pax are loaded... The fuel situation is different though.. the FMC constantly compares sensed (from the quantity indicating system) to calculated fuel quantities and iff they differ by more than 9000pounds a message is displayed on the CDU... The 2 figures are equalised on engine start though... Either way 247 tonnes is an impossible weight for a loaded aircraft that is about to do a 9 hour flight... One of the two pilots should have twigged at that... Given that Gross Weight is manually entered into the FMC and Fuel Qty is already sensed (ie.. the a/c knows how much fuel it has)... Given that the empty weight is IIRC around 180tonnes that leaves only 70tonnes of fuel and payload for a 9 hr.. flight... Regards, BB. > Given > that the empty weight is IIRC around 180tonnes that leaves only 70tonnes of > fuel and payload for a 9 hr.. flight... More like a three-hour tour, a three-hour tour ... GB said.... GB> I asked the question a few years back: "Does the aeroplane know GB> how heavy it is when it is sitting on it's wheels?". GB> IIRC, it doesn't. I imagine that it wouldn't be a particularly GB> difficult thing to integrate in a new design, just a bunch of GB> load-cells at various points in the gear mounting points. Perhaps the weight can be entered into a computer (FMC?) by the flight crew during pre-flight? That way, the computer should be able to tell you what power settings are required for takeoff. With respect to the throttles, are they directly linked to the engines' fuel control valves? Or is it done via computers. ie: you set the levers and the computer then tells the engines what to do? > Perhaps the weight can be entered into a computer (FMC?) by the flight > crew during pre-flight? That way, the computer should be able to tell > you what power settings are required for takeoff. Unless they weigh every passenger, what good is knowing the mass of everything else? Neil Gerace said.... >> Perhaps the weight can be entered into a computer (FMC?) by the flight >> crew during pre-flight? That way, the computer should be able to tell >> you what power settings are required for takeoff. NG> Unless they weigh every passenger, what good is knowing the mass of NG> everything else? Don't they get payload weight and other info when calculating fuel loads and stuff, and in this case, the power needed for takeoff? >> Perhaps the weight can be entered into a computer (FMC?) by the flight >> crew during pre-flight? That way, the computer should be able to tell >> you what power settings are required for takeoff. > >Unless they weigh every passenger, what good is knowing the mass of >everything else? The passenger population is large enough that averages can be used, and the resultant error is likely to tiny relative to the tow. Remember that the actual weight of the aircraft is rarely known to better than 1% anyway. There have been efforts to put strain gauges on the undercarriage in the past. It just doesn't work very well for a variety of reasons. The real problem in this case was a lack a common sense, and lack of any intuitive feel for the aircraft and mission. >There have been efforts to put strain gauges on the undercarriage in >the past. It just doesn't work very well for a variety of reasons. To whit... > >There have been efforts to put strain gauges on the undercarriage in > >the past. It just doesn't work very well for a variety of reasons. > > To whit... I'm guessing here: oil pressure in the dampers may vary in complicated ways according to other factors than sprung mass, so maybe that's why damper pressure is not a good guide to mass. > > matt weber wrote in message > <0k9auvoo903uscmr6kub20bgktu370hejp@4ax.com>... [quoted text clipped - 6 lines] > according to other factors than sprung mass, so maybe that's why damper > pressure is not a good guide to mass. Well for starters it isn't just oil in there either - they're inflated with nitrogen. Just like you can't tell the weight of an aircraft by measuring tyre pressure you can't tell it by measuring the pressure in the struts... Regards, BB. > Well for starters it isn't just oil in there either - they're inflated > with nitrogen. Just like you can't tell the weight of an aircraft by [quoted text clipped - 3 lines] > Regards, > BB. That's all very true, however load cells have been around for decades. Install one on each strut, above the dampers. The dampers woud have to be locked while being loaded and calculations done from a known weight condition. A close approximation of mass coud be calculated from the amount of brake pressure required to stop the aircraft during its last (say) 5km/h. Nothing's impossible if you don't gotta do it yourself. Cheers Dave Kearton Dave Kearton wrote in message ... >Nothing's impossible if you don't gotta do it yourself. :-) :-) > > Well for starters it isn't just oil in there either - they're inflated > > with nitrogen. Just like you can't tell the weight of an aircraft by [quoted text clipped - 17 lines] > > Dave Kearton That's been done as well.... I recall Boeing used to offer as an option a system that could work out c.o.g. and aircraft weight... All I know is it isn't offered anymore so it couldn't have been infallible (I don't think QF's a/c ever had it) ... Matt Weber alluded to such in an earlier post... There are strain gauges fitted to landing gear on some a/c though... On 747-400s that are fitted with carbon brakes braking force is limited to prevent excessive loads being transmitted to the aircraft structure. Limiting is through the antiskid system and is sensed by strain gauges... For those interested (looking at notes) it's approx 30,000 foot.pounds Regards, BB. > The dampers woud have to be locked while being loaded and calculations done > from a known weight condition. A close approximation of mass coud be > calculated from the amount of brake pressure required to stop the aircraft > during its last (say) 5km/h. > > Dave Kearton But that's the mass at the end of the last sector, which isn't all that useful at the start of the next one. JB >> > matt weber wrote in message >> <0k9auvoo903uscmr6kub20bgktu370hejp@4ax.com>... [quoted text clipped - 12 lines] >measuring tyre pressure you can't tell it by measuring the pressure in the >struts... pressure x area = force, irrewardless of how the pressure is applied (oil or air or nitrogen), but the original post said strain gauges (yes, which CAN be used to measure pressure) which can be/are applied to a structure to measure the load applied to it. Ie, the u/c attach structure could be strain gauged...... Matt reckoned there are a variety of reasons why strain gauging doesn't work very well on u/c and since strain gauging is one of the things I've done a lot of, I asked what the variety of reasons are. > pressure x area = force, irrewardless of how the pressure is applied (oil or > air or nitrogen), but the original post said strain gauges (yes, which CAN > be used to measure pressure) which can be/are applied to a structure to > measure the load applied to it. Ie, the u/c attach structure could be > strain gauged...... What you say is correct but I maintain that if it were that easy it would have been done by now (or at least the original system refined).. Perhaps the system was too inaccurate or was prone to failure to be of use? (along the lines of maybe the optional tyre pressure monitoring on the 747-400)? Regards, BB. >"RT" <r.thomas@cqu.edu.au> wrote in message >> pressure x area = force, irrewardless of how the pressure is applied (oil [quoted text clipped - 3 lines] >> measure the load applied to it. Ie, the u/c attach structure could be >> strain gauged...... > What you say is correct but I maintain that if it were that easy it >would have been done by now (or at least the original system refined).. >Perhaps the system was too inaccurate or was prone to failure to be of use? >(along the lines of maybe the optional tyre pressure monitoring on the >747-400)? (From another post) > I recall Boeing used to offer as an option > a system that could work out c.o.g. and aircraft weight... All I know is it > isn't offered anymore so it couldn't have been infallible No system is infallible, but a strain gauge based one is about as close as you're going to get :-) A pedestrian interlock/input from such could have saved an abraded bum of a SIA heavy :-) > it > > isn't offered anymore so it couldn't have been infallible [quoted text clipped - 4 lines] > A pedestrian interlock/input from such could have saved an abraded bum of a > SIA heavy :-) Agreed... the strain gauges that are fitted to the 747-400 landing gear (read my other post) for brake torque limiting are pretty reliable but always seem to have residual torque displayed whenever I've seen it on the CMC - they get re-zeroed though... Maybe that's a problem for using such to display weight on the gear? Regards, BB. > Agreed... the strain gauges that are fitted to the 747-400 landing gear >(read my other post) for brake torque limiting are pretty reliable but >always seem to have residual torque displayed whenever I've seen it on the >CMC - they get re-zeroed though... Maybe that's a problem for using such to >display weight on the gear? Depending on what is going on, temps etc you can get a little bit of drift but for both torque and load on u/c the gauges could be zeroed as soon as the u/c is retracted. As far as torque goes, depending on where the gauges are installed there could be a residual load (= strain) on brake release I'm surprised they aren't fitted anyway, as that would be the best measure of a heavy landing. But if I understood one of JB's recent posts, the u/c is supposed to put up with a 600 fpm descent while a 200 fpm arrival is classed as heavy, so p'raps there's no point in gauging the u/c for maintenance purposes :-) > I'm surprised they aren't fitted anyway, as that would be the best measure > of a heavy landing. I think you'll find that they use a whole bunch of g-meters in the heavy landing case. > But if I understood one of JB's recent posts, the u/c is supposed to put up > with a 600 fpm descent while a 200 fpm arrival is classed as heavy, so > p'raps there's no point in gauging the u/c for maintenance purposes :-) It would be 'heavy' from the point of view of the occupants, though not the aircraft. The A4 used to impact the ground at around 700 fpm, which was why it had such a gangly undercarriage. I'd hate to think what 600 fpm would feel like in a big fella... JB JB wrote in message ... >> I'm surprised they aren't fitted anyway, as that would be the best measure >> of a heavy landing. > >I think you'll find that they use a whole bunch of g-meters in the heavy >landing case. Fair enuff - that'd do it. >> But if I understood one of JB's recent posts, the u/c is supposed to put >up [quoted text clipped - 5 lines] >it had such a gangly undercarriage. I'd hate to think what 600 fpm would >feel like in a big fella... I think I'd rather be outside, watching, than sitting in cattle class when it happened! :-) > A pedestrian interlock/input from such could have saved an abraded bum of a > SIA heavy :-) Perhaps, although as I see this incident it has a couple of different components. The use of the wrong weight meant that the Vspeeds were incorrectly calculated, and perhaps more importantly, that the thrust setting was too low. Nevertheless, I wonder whether the total performance wouldn't have still been in the region of an aircraft with an engine loss at V1. One of our mathematicians can probably set to and work that out... The tail scrape happened, not because they rotated early, but because the rotation was continued, even though the aircraft hadn't lifted off at the normal attitude. Stopping the rotation at 8 or so degrees, would have avoided the scrape and probably given more acceleration (how much drag is involved in trying to remodel the back end?). Knowing, as they should have, that the tail will hit the ground, should have given them a mental maximum pitch attitude. Pushing the throttles to the firewall at the first indication of something abnormal should have been an instinctive reaction. In other words, there wasn't much real flying happening. JB JB wrote in message ... >The tail scrape happened, not because they rotated early, but because the >rotation was continued, even though the aircraft hadn't lifted off at the [quoted text clipped - 5 lines] >indication of something abnormal should have been an instinctive reaction. >In other words, there wasn't much real flying happening. Can't argue with that! >>> > matt weber wrote in message >>> <0k9auvoo903uscmr6kub20bgktu370hejp@4ax.com>... [quoted text clipped - 22 lines] >very well on u/c and since strain gauging is one of the things I've done a >lot of, I asked what the variety of reasons are. The biggest headaches are probably temperature compensation, and envirornmental issues in the under carriage area. It has been tried, and it apparently a whole more trouble than it is worth. >The biggest headaches are probably temperature compensation, and >envirornmental issues in the under carriage area. Mmm - can't get very excited about either of those - particularly since you need the numbers just shortly before departure only, when temps will have stabilised anyway. > It has been tried, >and it apparently a whole more trouble than it is worth. <shrug> "matt weber" <mattheww50@cox.net> wrote in message > The biggest headaches are probably temperature compensation, and > envirornmental issues in the under carriage area. It has been tried, > and it apparently a whole more trouble than it is worth. Can't imagine temperature variation being a significant factor. If a 4 element bridge is used this removes the effect of temperature change. It functions in the same way as a Wheatstone Bridge. When properly designed applied voltage and temperature do not effect the result. John > Well for starters it isn't just oil in there either - they're inflated >with nitrogen. Just like you can't tell the weight of an aircraft by >measuring tyre pressure you can't tell it by measuring the pressure in the >struts... Actually, you can. And such methods are widely used in heavy automotive applications, such as dump trucks in the 85 to 250 ton load class. EG, Caterpillar's VIMS. Different application, but functionally the same, with a large difference between empty and full weights. Measuring tyre pressure is actually a better way in some respects than measuring strut pressure for determining mass! Just because something is not done, it does not follow that it can not be done. Careful attention to detail as to what you load is quite a satisfactory method of determining TOW, and probably more accurate than a pressure measurement system would be. But rather than go to all this trouble, there are a number of suitable off the shelf technologies that could give aircraft weights accurately on the apron, if it was such an issue. cheers, Paul Saccani Perth West Australia ----- Original Message ----- From: "Paul Saccani" <traptinnedspicedham@hotmail.com> Newsgroups: aus.aviation Sent: Sunday, December 28, 2003 3:56 PM Subject: Re: SQ286 tail strike AKL March 2003 - TAIC Report > > Well for starters it isn't just oil in there either - they're inflated > >with nitrogen. Just like you can't tell the weight of an aircraft by [quoted text clipped - 8 lines] > Measuring tyre pressure is actually a better way in some respects than measuring > strut pressure for determining mass! I would think a strain gauge mounted on each of the struts would be easier, cheaper and much more accurate than monitoring tyre pressure. How do you know you haven't got a change in pressure due to a leak? And temperature changes would be a real challenge to maintaining accuracy. > Just because something is not done, it does not follow that it can not be done. > [quoted text clipped - 5 lines] > shelf technologies that could give aircraft weights accurately on the apron, if > it was such an issue. Agreed - a variation of the common weighbridge. However at busy airports you would need several and ultimately this option may not prove feasible. > cheers, > > Paul Saccani > Perth West Australia Cheers, John Paul Saccani said the following on 28/12/2003 1:56 PM: > But rather than go to all this trouble, there are a number of suitable off the > shelf technologies that could give aircraft weights accurately on the apron, if > it was such an issue. I think you have given an example of the power of lateral thinking: don't try to measure the weight of the aircraft from the aircraft, measure it from the ground. At the very least it could be a good check of the pilots calculations (and give a more accurate indicator of passenger weight when the plane is full of Samoan footballers and Japanese Sumo wrestlers). >The passenger population is large enough that averages can be used, >and the resultant error is likely to tiny relative to the tow. Sometimes. Take a look at the case a few years back at Gander, where using average pax. weights for a non-average group of passengers meant that the aircraft was in fact overloaded, ultimately causing the death of all on board. Average pax. weights need to be treated with more caution than I fear they are. cheers, Paul Saccani Perth West Australia >>The passenger population is large enough that averages can be used, >>and the resultant error is likely to tiny relative to the tow. [quoted text clipped - 8 lines] > Paul Saccani > Perth West Australia • PACIFIC PASSENGERS TOO BIG: Boeing 737 seats often have to be left empty to comply with weight restrictions because Pacific islands passengers are on average the heaviest and widest in the world, according to the Association of South Pacific Airlines >> Perhaps the weight can be entered into a computer (FMC?) by the flight >> crew during pre-flight? That way, the computer should be able to tell >> you what power settings are required for takeoff. > > Unless they weigh every passenger, what good is knowing the mass of > everything else? There is a deemed average weight for each passenger plus carry-on luggage set by the US FAA of 190 pounds in summer and 195 pounds in winter (to allow for heavier winter clothing). Airline can either use these figures, or carry out their own survey of their passengers to find average weights and use those. Of course, being averages these numbers will never be correct, however they should even out fairly well, especially on larger planes. Scott. > GB said.... > [quoted text clipped - 8 lines] > crew during pre-flight? That way, the computer should be able to tell > you what power settings are required for takeoff. > With respect to the throttles, are they directly linked to the engines' > fuel control valves? Or is it done via computers. ie: you set the levers > and the computer then tells the engines what to do? That's what happens anyway. IIRC pilots enter either gross weight and fuel load (which is either sensed or calculated) or zero fuel weight and fuel load. The FMC then works out thrust settings for thrust management purposes (autothrottle). The autothrottle can be disengaged (as can the autopilot) and everything done manually.. All 747-400s have electronic engine controls of some sort (the detail varies with engine manufacturer). The EEC controls engine thrust according to commands from the throttle position or FMC (when autothrottle active) .. Regards, BB. > GB said.... > [quoted text clipped - 8 lines] > crew during pre-flight? That way, the computer should be able to tell > you what power settings are required for takeoff. That's more or less what happens. You can enter the ZFW and the FMC will add the fuel load (which it can measure directly) for a GW, or alternatively, you can enter the GW, and it will calculate the ZFW. Generally, when you want access to the numbers before fuelling is complete, you enter the planned GW, but the entry of the correct ZFW, and final GW should be checked as part of signing off on the loadsheet. The FMC does calculate a set of Vspeeds, but it doesn't have data for the individual airports and is just generating a generic figure. Normally the computer generated figures are then overwritten by the crew, though they should be in a similar ballpark. The FMC doesn't generate the actual power figures, as these are normally derated, and it only provides the full standard rating numbers. A normal sort of sequence for the generation of the performance data would have the FO work out all of the Vspeeds and thrust settings, without any input from the Captain. He would then enter them into the FMC. The Captain would then work out all of the numbers himself, and he would then check his results against whatever is in the FMC. Later, when briefing for the departure, and after the final loadsheet, the flying pilot would brief his calculated numbers, and they would be crosschecked/reentered in the FMC by all of the pilots. The Pegasus FMC in the -400s drops any data entered early in the preflight when the final loadsheet data is entered, so unless quite a few steps are skipped, it should be entered twice. JB > With respect to the throttles, are they directly linked to the engines' > fuel control valves? Or is it done via computers. ie: you set the levers > and the computer then tells the engines what to do? The thrust levers are basically an interface to the thrust management computers. Unlike the Airbus, they move with power changes, but the system behind them isn't all that different. The fuel control valves are there to cut the fuel supply off.....they're the last thing I'd let a computer have control of. JB <snip more JB good stuff> Give that the FMS interface to even the dunny door now days, I am a little supprised that the oleo pressures are not picked off and fed in as well. Seems a really basic thing to do. SignaturePaul Repacholi 1 Crescent Rd., +61 (08) 9257-1001 Kalamunda. West Australia 6076 comp.os.vms,- The Older, Grumpier Slashdot Raw, Cooked or Well-done, it's all half baked. EPIC, The Architecture of the future, always has been, always will be. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2010 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.