SFO Crash Myths

[caesar novus]

Although this is very early to analyze the Asiana Airlines crash http://usnews.nbcnews.com/_news/2013/07/07/19337501-i-have-trouble-audio-from-cockpit-reveals-moments-after-deadly-crash?lite&gt1=43001 I would like to take the risk of denying the myths that I have already heard being spread by news commentators who don't have much clue about flight..

 

1) "The gears started shaking in the cockpit":

 

No gears, but they must mean the stall warning device shook the controls to get pilot attention.

 

2) "They came in too slow and low":

 

NO! that was just during the last moment where they overcorrected or whatever. The glidepath was absolutely too high, too steep, and probably too fast for all but the last few seconds. 

 

3) "The pilot was a trainee with lots more experience than his 43 hours in that aircraft implies":

 

Groan.... so he had equivalent of 4 pacific crossings and a ton of hours in simulators and other aircraft. Do you realize he was offered rare permission to experiment with a manual visual approach without the usual autopilot guidence that would keep him nailed on proper glidepath?

 

They were departing from Seoul; do you realize there was a famous co-pilot syndrome connected with multiple Korean Airline crashes, where they would fail to correct fatal but recoverable errors by the pilot out of respect for their social rank? This not a Korean airline, but what about the instructor copilot? Well, a timid instructor seems a stretch, but instructors often push their student to a stressful limit and may have setup something tricky for this trainee pilot.

Edited July 8, 2013 by caesar novus

[caesar novus]

It's just too painful to hear the news muddle proceed... now they say a firetruck appeared to kill at least one of the 2 non-survivors. I saw yesterday an interview with the so-called firechief on the scene, and was struck by her seeming to appear about 17 years old. OK, maybe a young looking 27 year old, but what are the chances of her being more qualified for the top job than the huge pool of more experienced ones?

 

SFO is the leading edge of spreading hiring practices based only on being a minority and not a drop on administrative qualifications. All fire departments should be privatized and jobs not treated as rewards to dole out, but with position, pay and benefits based on the actual job marketplace rather than rigged up monopolies.

 

They are still harping on the low and slow glidepath instead of the root cause anomaly. If my detailed preliminary info is correct, the problem was an awkward recovery from a too high and steep glidepath. Then you are like on a roller coaster with too much energy/speed that has to be quashed. The inexperienced pilot appeared to overcorrect in flattening out and slowing down way too much in a drastic last minute fashion. The instructor co-pilot probably artificially set up this challenge to practice landing under difficult conditions.

 

There may have been some equipment failure, but it wasn't that they were merrily coasting in and failed to power up. Everything was going their way in terms of excess speed and altitude even if their engines quit.. they had to intentionally try hard to slow down... it was almost more surprising they didn't overshoot rather than undershoot.

Edited July 9, 2013 by caesar novus

[caesar novus]

OK, the still preliminary info seems to begin to gel now... The pilot doing his first landing with that type of plane and the instructor copilot doing his first teaching flight... apparently armed but didn't activate the auto speed control. Or it possibly deactivated... point being they thought the speed was taken care of until too late.

 

In a car I notice if cruise control failed to activate or kicked off, because once you drop one iota in speed the sharks immediately swarm around you in reckless passing. They didn't have that feedback; so there's my quota of compassion and maybe a direction for improvement in yet another cockpit warning. I do wonder why they would put 2 first timers together in a landing.

 

Anyway, to wrap up my myth paradigm: It may be a myth that the deaths were caused by the airline crash... one or both were possibly clobbered by "rescuers". I always am wary of  good samaritans because they are blinded by their good intentions and tend to do unintended damage.

 

And most importantly, based on the black box info that was unprecedently released immediately, I can still say the low and slow theory may be a myth. If they were in proper and normal glidepath, they should have noticed earlier the speed wasn't being automatically kicked in. But in that unusual steep descent, they had all the speed they needed just by gravity... until the last few seconds when they needed juice fast.

[caldrail]

The problem with an airliner in glide mode ios that it has various quialities that are greatly emphasised compared to smaller aeroplanes. They are very efficient airframes and in theory can glide very well indeed, but on the other side of the coin, the heavier weight will reduce performance. The recent Hudson River episode shows a good example of a pilot refusing a directive to make for a runway - in his opinion he couldn't make it - and subsequent tests showed that in perfect conditions 50% of attempts to make a runway failed, and with other considerations like extending the performance by activating the APU to keep electrical services online (which was the case at the Hudson River). However, as investigators found, emergency procedures are written for high alitiude alerts and the length of checklists makes low level emergencies very distracting and difficult to handle.

 

From a purely aerodynamic point of view, airliners can sometimes adopt very high angles of attack and if the aeroplane stalls in this condition during what might appear to be a steep but otherwise undramatic approach, the aircraft might prove difficult to recover - remember that the aeroplane is loasing height rapidly at low altitude. With heavy jets the key phrase is 'sink rate', or the speed of descent which is not necessarily linked to the axis of the aeroplane.

[caesar novus]

It's been confirmed that the fire truck killed one of the victims. It  was under the supervision of a very immature looking fire chief, and just reminds me of the dysfunctional public sector situation in California. Steven Greenhut's "Plunder!" book documents a world where merit or experience can mean nothing but instead is on some reckless utopian social experiment.

 

A local newspaper recently quoted a United Airlines pilot who instructed at Korean Air for 5 years. He also brought up the cultural issue of Korean copilots being reluctant to correct a pilot. Also he said those students tended to be overly trustful of technology (thus not monitoring autopilot closely?). Normally this would raise red flags for some who seem to believe the world is driven by racism, but this was a well documented issue in multiple Korean Air crashes.

 

Last I heard Korean Air itself solved their safety record with strict training that a copilot in any doubt of the pilot immediately take over and simply say "I've got the controls". All airlines apparently teach that now, and insist pilots defer to it. The "Air Disasters" documentary episodes showed in chilling detail both a Korean and non-Korean co-pilot failing to over ride a pilot who they see making correctable but fatal mistakes. 

 

With heavy jets the key phrase is 'sink rate', or the speed of descent which is not necessarily linked to the axis of the aeroplane.

 

You're talking about good glide angle but high sink rate and thus excess speed. First of all, I only brought up Asiana's fast/steep glide as being a factor that allowed them to not notice their speed autopilot was disengaged. If they weren't playing training games and had a normal descent, they would have needed power kicking in earlier and overridden it before it was too late, 

 

Secondly, I think it's a shame airline pilots don't get elementary glider experience. The "Air Disasters" series had two episodes of airline pilots gliding into landing. You have to come in high, because as seen in SFO falling short is a disaster. Then you land steeply and fast as did a French airliner who took off with an empty fuel gauge which they thought was faulty. The pilot glided back to the Atlantic island for 45 minutes and scared the passengers with a fast bumpy landing.

 

Or you land steeply and elegantly, such as a Canadian pilot who knew how to forward slip a sailplane. He had no power to lower the airliner flaps, but plopped down nicely even on a disused Ontario runway with kids biking on it. I love forward slips which synchronize the stick and pedals backwards to increase drag, and even wonder if it might help to alternate a forward slip from side to side to further increase the safe descent angle.

Edited July 30, 2013 by caesar novus

[caldrail]

People sometimes get away with some serious antics in light aeroplanes. I once saw a guy land a motor glider with a last minute steep turn pver the control van. Not recommended. But then I used to land early model C150's with full flap at 40deg - the plane comes down at a heck of an angle but useful for getting into a field in a short distance - which is not recommended as I discovered from an instructor afterward. Nor for that matter is excessive crabbing recommended for landing -  the problem being that if encountering variant airflow at low altitude you really can't do much about it.

 

One intersting thig about airline flying isn't so muuch what they learn on, but what they practice every day. A bunch of guys were taught to fly a spitfire for a documentary recently. The airline piot failed the course before qualifying on Tiger Moths because he was used to the 'fly by wire' response and momentum of a heavy Airbus.

 

'Sink rate' is a situation that can afflict heavy aeroplanes and isn't necessarily linked to glide angle. Some modern jet airlines will descend happily in a near or fully stalled state thanks to their stability design and control system. If your downward velocity is excessive you're looking at potential undercarriage collapse and please remember that the pilot will naturally want to 'flare' his aeroplane at the last moment, causing extra load on the gear because of the length of the aeroplane and therefore the undercarriage members longitudinal offset.

 

Airliners are quite efficient gliders as it happens but unfoprtunately they tend to have lots of freight or people strapped in the back, weight that restricts their performance, and for that matter, attempting to glide back to the field is one of the most lecturable mistake an instructor will berate you for. Generally you won't make it, and trying to extend a glide to do so leads to disaster, which is the case in point as in recent years a light aeroplane crashed trying to return to the runway. A better policy is finding a landing spot ahead, if possible. Wrecking an aeroplane is fine if it's done controllably and you can all walk away from it after.

 

I don't know about America, but in Britain the phrase is "I have control", which must be confirmed by the other pilot. I do understand however that in the recent Hudson River landing the senior pilot said "My aeroplane" for the same effect (and it was confirmed by the co-pilot)

[caesar novus]

High sink rate is normally easily tamed through ground effect and aggressive properly timed flares, if the runway is long enough. You get cushion from your wingtip vortices squashing against the ground, and flares can convert forward/downward speed into lift and drag. There can be a problem with moveable passengers; a bunch of people changing seats in a small turboprop can shift to bad CG which can prevent or prematurely promote flares.

 

Airliners don't do well with off runway landings. There was one success recently covered in Air Disasters where a south/latin American airliner glided onto a random grassy area in California, and later even flew off after an engine and tire was replaced. But it turned out to be a manicured area at a Nasa facility that maybe was intended for future emergency air use, although unmarked and unused.

 

Of course the French pilot I mentioned did better gliding to his island of departure rather than ocean landing (craggy coast without rescue infrastructure). He had the wisdom to set up biased toward overshoot rather than undershoot, but he didn't know how to angle down with a slow forward slip once the runway was guaranteed. So they probably got a lot of fright lawsuits from the fast and bumpy panic braking.

 

The Canadian airline pilot did right to aim for an inland runway because he was also a sailplane pilot whose every molecule is tuned to never land short (a la Asiana) and with a bag of tricks to avoid running long after the runway is guaranteed. Landing off field is tricky with half invisible power lines, and even your runway may have stone walls or trees at the end. In Alaska, I guess they encourage light aircraft pilots to practice emergency landing on freeways even amongst traffic

 

The "I have the controls" phrase and it's mandatory acceptance by the other was presented as an airline company policy. First by Korean Air, then by others. Even useless remedies may need to be followed to avoid lawsuits in future crashes. But I think it could have helped for instance the case of a Korean co-pilot who recognized the fatal mistake of his retired-general ex-fighter pilot. It was almost understandable that the co-pilot struggled for the right words, which probably was a familiar pattern  because I think the senior pilot had been a poor student at airliners.

Edited August 14, 2013 by caesar novus

[caldrail]

High sink rates are a hazard that can cause serious accidents and ground effect won't stop it, especially very heavy large aeroplanes. For that matter, flaring has to be done right or it adds to your woes. I remember watching a Philipino lady under training and she could not get it right, always flaring too early, and causing some very abript arrivals. The poor woman broke down in tears outside the hangar and I'm not sure the instructor was able to convince her to continue.

Airliners are not all terrain vehicles. Nor are they designed for coping with rough strip operation, being intentionally designed to operate from smooth weight bearing concrete/asphalt runways. Also being nose wheel aeroplanes they are inherently prone to nose wheel collapses. Sometimes you need to operate from strips in an ad hoc fashion though this often requires permission, such as getting resident aeroplanes out of Meigs Field in Chicago on the taxiway after the strip was sneakily closed without due warning by Chicago's mayor. In another incident, I recall a light aeroplane that had force landed in a field due to technical problems was allowed to access an adjacent road as a runway in southern Britain, closed off by police for the event, which given the nature of rural roads, must have been a nail biting experience.

Airliners are less aerodynamically suited to sideslip because of their swept wing design, being far more likely to suffer wing drop, and at low altitude in a heavy aeroplane recovery would be impossible and might make the accident worse if you tried as an incipient spin is provoked by use of aileron. In any case the resulting sink rate is not advisable in such large aircraft. This is why flying airlioners is an exercise in accurate flying to begin with - you have less margin for error than light aircraft.

I once landed Concorde on an aircraft carrier. The only way to achieve it was to approach low at minimum speed, nose high, and stall it onto the deck with minimal clearance, then swerve side to side to increase braking distance. But of course that was a flight simulator. Plenty of tricks - I doubt anyone could pull that off in real life, or ebven envisage trying.

The "I have the controls" phrase and it's mandatory acceptance by the others has been standard practice since at least before WW2 in all spheres of flight. The wording might be subject to regional variations but the intent is always the same.

[caesar novus]

You worry about sink rate, but the aviation world doesn't need to. You can simply dive low to build up energy, then level out or even climb if you wish...  simply on your retained energy with no engine power at all. Sink rate problem gone, you've just got to time it right when and over where your speed bleeds off, like Asiana didn't.  
 
At my previous location it used to be a fetish of recreational pilots to do a virtual suicide type dive on landing approach to blast thru wind shear layers... the surface wind howled in a much different direction than winds just a bit higher, and could stall or disrupt a pokey pilot at the transition. But they did it more for showoff and the excitement of flattening down on that ground effect at high speed.
 
You criticize side slips, but I specifically said forward slip (contrasted here with sideslip http://en.wikipedia.org/wiki/Forward_slip#Forward-slip ) which go straight and worked great. 

In the United States, student pilots are required to know how to do forward slips before embarking on their first solo flight. The logic is that in the event of an engine failure, the pilot will have to land on the first attempt and will not have a chance to go around if the aircraft is too high or too fast.

 
Dialogue is going in circles partly because the difficulty of me multi-quoting. You denied my explanation of the control handoff, saying it required confirmation, then went back to agree with my original explanation with the addition that it is an eternal practice. Umpteen official crash evaluations disprove that, and in 1990's led various airline companies to train copilots to easily and assertively utilize that phrase, and for head pilots to respond submissively. If you disagree, take it up with the Smithsonian tv channel.

Edited August 16, 2013 by caesar novus

[caldrail]

 

You worry about sink rate, but the aviation world doesn't need to. You can simply dive low to build up energy, then level out or even climb if you wish...  simply on your retained energy with no engine power at all. Sink rate problem gone, you've just got to time it right when and over where your speed bleeds off, like Asiana didn't. 

????!!!!!!!

I don't worry about sink rate - I don't have to - I'm not ATPL qualified and therefore limited to 5 tons AUW, in which sink rate is less of an issue (and actually not part of flight training at that level since training aircraft are far more responsive to input and ground effect) . Your method of sink rate avoidance actually doesn't do that - all you're doing is managing energy in a different style and risking a worse sink rate by manovering in that manner at potentially low altitude - such manoevers are not recommended - you're dealing with aeroplanes often weighing in excess of twenty tons with considerable momentum. Far better to plan your arrival ahead and arrive in the safest attitude and aerdynamic condition possible.

The problem here of course is that as the aeroplane slows down the controls are less effective. With control surfaces designed for airspeeds edging toward the speed of sound on aeroplanes that are significantly heavier than a typical trainer, there is reason to avoid such low speed manoevers.
 

At my previous location it used to be a fetish of recreational pilots to do a virtual suicide type dive on landing approach to blast thru wind shear layers... the surface wind howled in a much different direction than winds just a bit higher, and could stall or disrupt a pokey pilot at the transition. But they did it more for showoff and the excitement of flattening down on that ground effect at high speed.

That wouldn't be tolerated in Britain. Field operators would risk losing their license and would soon put a stop to such antics. Serious cases would be result in prosecutions - One guy I know of whose flying is a bit on the wild side has become somewhat notorious for court appearances, and the fines levelled against pilots are in thousands of pounds, not hundreds as you would exopect for driving offenses.
 

You criticize side slips, but I specifically said forward slip (contrasted here with sideslip http://en.wikipedia....ip#Forward-slip ) which go straight and worked great.

Forward slips are side slips (I wouldn't pay too much attention to Wikipedia on that point). Crabbing is merely creating a controlled side slip condition and swept wing aircraft have serious issues with them, not least that the trailing wing is no longer generating lift because the airflow is both masked by the fuselage and the airflow along the wing rather than across it.
 

    In the United States, student pilots are required to know how to do forward slips before embarking on their first solo flight. The logic is that in the event of an engine failure, the pilot will have to land on the first attempt and will not have a chance to go around if the aircraft is too high or too fast.

I should jlolly well hope so too. As it happens British flight training aims to get a pilot flying solo as soon as possible which by definition involves coping with potential engine problems at any stage of the flight.
 

Dialogue is going in circles partly because the difficulty of me multi-quoting. You denied my explanation of the control handoff, saying it required confirmation, then went back to agree with my original explanation with the addition that it is an eternal practice. Umpteen official crash evaluations disprove that, and in 1990's led various airline companies to train copilots to easily and assertively utilize that phrase, and for head pilots to respond submissively. If you disagree, take it up with the Smithsonian tv channel.

Television? Only the second worst source of information ever devisd by man.

Edited August 20, 2013 by caldrail

[caesar novus]

I have only randomly seen a few news updates, but now the young genius who is playing grownup sfo firechief at probably hyper extortionate taxpayer expense has appalled many by banning the use of helmetcams that showed they were running over passenger. Even the crew want helmetcams as a way of improving, and in this case the cam evidence pointed to higher ups not passing on certain  info to drivers. This is what you get by promoting public servants to the top based on alleged victimology rather than seasoned and effective candidates.

 

 

PS, forward slip doesnt involve one iota of slipping to a side... you proceed absolutely straight as if on rails (altho crooked heading) and this has included air canada swept wing airliners (they can barrel roll for heavens sake). You snuff the sideward slip with counter yaw, and genteelly float downward using all that crookedness as dive brakes.  It's not about correcting for sidewind, like crab or sideslip. Wiki has a better explanation with diagram somewhere, but that awkwardly phrased version is mostly correct and well emphasizes the centrality of this maneuver for even beginners.

Edited August 21, 2013 by caesar novus

[caldrail]

What's all this stuff about helmetcams? Airline crew don't wear helmets, nor have I ever heard of a crew videoing their own performance as "a means to improve" - why would they? Their flying record is regularly reviewed and subject to testing at intervals.

 

 

PS, forward slip doesnt involve one iota of slipping to a side.

 

PPS - You ought to learn about flying because you couldn't be more wrong. Side slip is when an aircraft has a sideways component of travel. My instructor used to challenge me about "flying out of balance" because that was effectively side slipping, or as you put it, foward slipping. I would avoid using those bogus definitions of aviation you get from the internet. Actually, it would probably be better if you avoid trying to lecture me on flying. I may not be Biggles or a world authority, but I qualified for a PPL in two countries, have eight years of flying experience behind me, used rogallo wings as the basis of my physics project in my schooldays, and designed an aeroplane in my teens.

[caesar novus]

Reread your post... i say forward slip and you respond with sideslip... they have little connection in intent. You could go a whole flying career avoiding a sideslip, but even an early student should learn forward slip for emergency landings without power. All airline pilots should know it in case flaps become inoperable in total power outs like air canada (dead apu).

 

I didnt mean helmet cams for flyers, but firemen. It is becoming common and only a few places ban them including the now brilliantly timed sfo fire chief. I don't know her story, but california chiefs including police are famous for benefit extortion... so i hold them to high standard.

 

I posted quotes here a few years ago on how something like 40%? get "chiefs disease" in california where they claim backaches and pension off at astronomical rates. Towns have been bankrupted. We had that here where an unmotivated minority figurehead was named as a chief, then soon went on leave for months due to backache, then retired young with benefits times three. The problem is no market economy in public sector... the hard workers dont get rewarded but the incompetant and manipulators hit jackpots.

Edited August 22, 2013 by caesar novus

[caldrail]

Please do not use the phrase "Forward Slip" any further - it isn't standard aviation nomenclature. In fact, by defintion, all slips or skids are forward because otherwise it isn't flying, but crashing, and if the Americans do use that term, then that's typical of the poor standard of trainign they're infamous for.

[caesar novus]

Holy cow, I see in http://www.airlinepilotforums.com/flight-schools-training/38263-side-slip-forward-slip-4.html that the dc10 airliner series recommended the forward slip as their STANDARD worldwide crosswind landing technique... That was brought up by air force kc10 pilot who has the manufacturer manual. Boeing recommends the more conventional crab because any kind of slip can bonk stuff they hang under the wing into the ground. DC trijets had different geometry forgiving more bank, but very strange they didn't use sideslip.

 

Strange because if you do forward slip with crosswind, you yaw INTO the wind like a crab. With sideslip you yaw AWAY from the wind. Contrasting and putting them together is shown in this video, although I would rather see forward slip reserved as a simple emergency maneuver. Let the airline pilots bonk stuff in emergency, and they they can approach higher and not risk shortfalls like Asiana.

 

Edited August 23, 2013 by caesar novus