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Sheremetyevo Superjet 100 in flames

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Sheremetyevo Superjet 100 in flames

Old 8th May 2019, 17:13
  #341 (permalink)  
 
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Originally Posted by mnttech View Post
IIRC, All together. The cabin crew is supposed to use the Mark 1 eyeball to ensure it is safe to use the exit.
The question is about the lights in the floor, the aisle floor lighting, which is a good question.

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Old 8th May 2019, 18:09
  #342 (permalink)  
 
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the more I read about this accident and the more I wonder why they had such a hard landing. It seemed to be a relatively manageable event until they breached the wing tanks...
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Old 8th May 2019, 18:42
  #343 (permalink)  
 
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Originally Posted by atakacs View Post
the more I read about this accident and the more I wonder why they had such a hard landing. It seemed to be a relatively manageable event until they breached the wing tanks...
Even after the breech and fire it was still manageable within expectations. Design and testing provisions may still have been within expectations.in a survivable accident.

However there is still room to pick at human performance which is never assumed to be perfect.
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Old 8th May 2019, 20:28
  #344 (permalink)  
 
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Probably related to their technical probs after the strike.
Aircraft likely in Direct law, so handling differently in the flare.
Not flown the Su, so not sure if you still get the lift dump spoilers automatically in direct....
Might have been carrying a little extra speed too, for any one of a variety of reasons.

Leaving the engines running though, isn't something he's going to look back on happily.
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Old 8th May 2019, 20:37
  #345 (permalink)  
 
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Originally Posted by Nomad2 View Post
Probably related to their technical probs after the strike.
Aircraft likely in Direct law, so handling differently in the flare.
Not flown the Su, so not sure if you still get the lift dump spoilers automatically in direct....
Might have been carrying a little extra speed too, for any one of a variety of reasons.

Leaving the engines running though, isn't something he's going to look back on happily.
I agree, but maybe the shut down of the engine(s) was impossible due to massive damage....
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Old 8th May 2019, 20:42
  #346 (permalink)  
 
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The video seems to start just after a bounce, then landing pitched down on the nose wheel into the second bounce, hence why it's so violent. Then again a pitch down, unloading the wings completely, at which point you can't expect the structure to withstand now a basically ballistic flight. Attempted corrections are out of phase with the motion, which only amplifies the error.

The conditions initiating the first bounce may be somewhat unique, but from there on the events are likely similar to other bouncing accidents.

SJ100:

Fedex MD11, Tokyo 2009, @28sec:

Crash: Fedex MD11 at Tokyo on Mar 23rd 2009, turned on its back while landing in gusty winds

Is the MD-11 really dangerous to land?

Fedex MD11:
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Old 8th May 2019, 20:53
  #347 (permalink)  
 
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I was shocked (when I first saw the video of the bouncing a/c) by the speed of the aircraft. It looked unreal fast and I thought the playback speed was the problem. I could not imagine landing the a/c at that speed in the nose up attitude was possible, as there too much lift remained, so one had to push yoke forward to make a ground contact (nose wheel first). Or hold off forever till the speed reduced and run out of runway. Or, may be, I thought they were landing with a strong tailwind. Nop.

Now the article above mentioned the speed was 30 kts above "normal". However the pilot, in the interview, referred to the speed as "normal". Did he mean it was the target calculated t/d speed given the weight of the aircraft? Or was there glitch in the system producing under-inflated speed indications?

Also, given the excessive speed on the bounces, the revving engines pushing the fire out, post fire flaps looking like they were set for a climb - in other words, was there a go around attempt?
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Old 8th May 2019, 21:05
  #348 (permalink)  
 
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Owing to the electrical issues, is it possible that he had lost thrust control? Hence the possible speed control problems, bounces and then "leaving them on" (can't turn them off) after stopping?
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Old 8th May 2019, 21:38
  #349 (permalink)  
 
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Back in the dawn of turboprops, the Viscount had an automatic crash switch that among other things cut off fuel to the engines.
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Old 8th May 2019, 21:55
  #350 (permalink)  
 
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Originally Posted by bsieker View Post
Very unlikely for a short-haul airliner. They usually can land at maximum takeoff weight (or very slightly less) without any problems to allow very short hops without the need to refuel at every stop. And even larger types, which have a maximum landing weight significantly lower than maximum takeoff weight, can perform a safe overweight landing, but require an inspection afterwards.

Bernd
Quite right. All this talk of dumping fuel is nonsense. S/H planes can’t dump. And Even 747 can land at max TOW IN DIRE EMERGENCIES.
S/H planes can circle to burn off fuel but 1 tonne of [email protected] approx 2 tones/hr burn means 2 tones per hour. 1 tonne = 1 knot of approach speed so generally complete waste of time.
Cheers. Yan
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Old 8th May 2019, 21:56
  #351 (permalink)  
 
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Originally Posted by RatherBeFlying View Post
Back in the dawn of turboprops, the Viscount had an automatic crash switch that among other things cut off fuel to the engines.
Think about that for a second. A single switch (i.e. single failure), that will shutoff both engines.

You really want to advocate that?
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Old 8th May 2019, 22:53
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Think about that for a second. A single switch (i.e. single failure), that will shutoff both engines.
You really want to advocate that?
Not advocating so much as putting up for discussion. I suspect the certification authorities later decided against continuing the practice as it may raise more problems than it solves.

But it did take substantial g to trigger. There are a number of cars today that have a crash actuated fuel shutoff. I've had to reset one after a crash near my house.

One design has two metal balls on arms 90° apart that will close the valve on a sufficient frontal or side impact.

How the Viscount switch was done I don't know.
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Old 9th May 2019, 00:49
  #353 (permalink)  
 
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No spoilers?

The first bounce looks just like a bounce when the ground lift dump spoilers don't deploy, especially when your fast. The plane just careens right back up and continues flying, that is when a bounced landing go-around would be performed under normal circumstances. I have no idea what this crew was dealing with so will make no judgment on the landing.
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Old 9th May 2019, 01:37
  #354 (permalink)  
 
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Originally Posted by Ripton View Post
This raises the question of whether the strip lighting on the aisle floor designed to guide passengers to the exit would only come on in an emergency to guide passengers to emergency exits that had been opened or whether it all comes on together regardless that it might guide you in the wrong direction? Not something I've ever considered as a passenger before.
Originally Posted by etrang View Post
The question is about the lights in the floor, the aisle floor lighting, which is a good question.
Etrang, I agree.
Ripton, what I was trying to say, and did not, as far as I can remember, ALL the lights come on together. It is probably way too farfetched to have a system that can determine which lights come on at one time. Here in the US, these two 14 CFRs appear to be ruling:

§121.310 Additional emergency equipment.
(c) Lighting for interior emergency exit markings. Except for nontransport category airplanes type certificated after December 31, 1964, each passenger-carrying airplane must have an emergency lighting system, independent of the main lighting system. However, sources of general cabin illumination may be common to both the emergency and the main lighting systems if the power supply to the emergency lighting system is independent of the power supply to the main lighting system.
(3) For airplanes type certificated after January 1, 1958, after November 26, 1986, include floor proximity emergency escape path marking which meets the requirements of §25.812(e) of this chapter in effect on November 26, 1984..
§25.812 Emergency lighting.
(e) Floor proximity emergency escape path marking must provide emergency evacuation guidance for passengers when all sources of illumination more than 4 feet above the cabin aisle floor are totally obscured. In the dark of the night, the floor proximity emergency escape path marking must enable each passenger to—
(1) After leaving the passenger seat, visually identify the emergency escape path along the cabin aisle floor to the first exits or pair of exits forward and aft of the seat; and
(2) Readily identify each exit from the emergency escape path by reference only to markings and visual features not more than 4 feet above the cabin floor.
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Old 9th May 2019, 01:47
  #355 (permalink)  
 
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Originally Posted by RatherBeFlying View Post
Not advocating so much as putting up for discussion. I suspect the certification authorities later decided against continuing the practice as it may raise more problems than it solves.
You got that last part right. For starters, any single 'switch' would violate 25.903(b):
(b)Engine isolation. The powerplants must be arranged and isolated from each other to allow operation, in at least one configuration, so that the failure or malfunction of any engine, or of any system that can affect the engine, will not
(1) Prevent the continued safe operation of the remaining engines; or
(2) Require immediate action by any crewmember for continued safe operation.
So, at best, you'd need an independent system for each engine. Further, you'd need to come up with a G load that is both low enough to be survivable, yet at the same time high enough that the aircraft can't possibly still be airworthy - for example a very hard bounce, the pilot decides to go around, but your crash switch shuts off the engines and they crash due to the crash switch...
Where do you put the G switch - different parts of the aircraft can experience vastly different G loads in a hard landing. Oh, and for what should be obvious reasons, the regulators have taken a very, very dim view of any system that can unilaterally shut down an engine in-flight. Boeing has "Thrust Control Malfunction Accommodation" - TCMA - that will shutdown an engine that remains at high power with the throttles at/near idle - but it's only active on the ground. What sort of air/ground indication would you trust to still function and function properly when you just hit the runway so hard that the landing gear came off?

I worked engines for nearly 40 years - wouldn't touch a system like that with a ten foot pole. It would make MCAS look positively brilliant.
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Old 9th May 2019, 02:07
  #356 (permalink)  
 
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Originally Posted by Ripton View Post
This raises the question of whether the strip lighting on the aisle floor designed to guide passengers to the exit would only come on in an emergency to guide passengers to emergency exits that had been opened or whether it all comes on together regardless that it might guide you in the wrong direction? Not something I've ever considered as a passenger before.
it's generally all on if selected on by FC.

if it's not already on, it comes on due main power failure or selection by CC if thst option exists on the aircraft.

I can't speak for the SU100, but on most modern aircraft external EEL activates on opening of the armed cabin door (slide exit area lighting and fuselage moubted spotlights etc) and slide deployment will trigger integral slide lights (if fitted). This seems to be the norm in widebody dual lane slides like 777 or A380, less so on single aisles but I haven't operated in a 737 or A320 in years so perhaps they now have integrated slide lights too
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Old 9th May 2019, 02:13
  #357 (permalink)  
 
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Mnttech, its probably possible to have a system in which aisle lighting acticates only between usuable doors, but there's also flaws with that.

1. You want to already have pax at the door when opened to establish flow asap. So lights need to be already on when they're undoing their seatbelts. The chances of the door being unusable are mitigated by the time saved in having pax already there

2. If a door is usable then becomes unusable there needs to be a way for the system to "know" this. Too hard and too variable since the CC need to make that call. Easy for the crew to overlook the step of pressing a button for example in the chaos of evac.

maybe it could be done but the benefits don't seem to be worth the multiple ways it could complicate things.

definitely worth some research though.
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Old 9th May 2019, 06:07
  #358 (permalink)  
 
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mntech and givemewings,

Thanks for both of your answers.

I had suspected it would be an "all on" system but hadn't really thought about it before reading about this accident. I fly long haul on a monthly basis and always make sure I know where the nearest exits are in relation to my seat but hadn't considered that it may not be possible to determine whether the choice to go towards the front or the back of the aircraft would be the correct one.

An "all on" system seems to be flawed in that it potentially leads passengers down a dead end but as you say, givemewings, an intelligent, automated system would be complicated.
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Old 9th May 2019, 06:30
  #359 (permalink)  
 
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Dual control rates

I only flew one jet which had different control systems / forces which was the DC10. We were only allowed to fly with CWS engaged although we flew a demonstration circuit at base and practised on the sim in manual.

In the 90s I modified a 17m phoebus C sailplane by putting a large lump of lead in the fin which moved the CofG to it's aft limit.
Flight test off a winch on a wet winters day required landing on 3m wide peri track. All went well until I flared, which I generally did late, the tail skid smacked into the concrete and I found myself 3m off the deck. (Change of effectiveness of all moving tailplane).
Fortunately I knew and had taught many what to do in a bounced landing having learnt the hard way on my first solo on an aircoupe which I attempted to destroy with a pio followed a few years later by dropping the oxygen masks and failing a couple of flight control valves on a jet.

The video appears to show that its yet another accident whose roots stem from system design, lack of understanding and training standards.

I lost a very good friend in Britain's worst disaster nearly 47 years ago. Nothing has changed nor will it until piloting is treated like a profession, rather than a job, and minimum standards are raised.
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Old 9th May 2019, 06:35
  #360 (permalink)  
 
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Originally Posted by RatherBeFlying View Post
Not advocating so much as putting up for discussion. I suspect the certification authorities later decided against continuing the practice as it may raise more problems than it solves.

But it did take substantial g to trigger. There are a number of cars today that have a crash actuated fuel shutoff. I've had to reset one after a crash near my house.

One design has two metal balls on arms 90° apart that will close the valve on a sufficient frontal or side impact.

How the Viscount switch was done I don't know.
I flew Viscount and I can assure you there was no such thing.
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