Air France plane missing?

[P3_Super_Bee]

I'd better post this again. I could swear I already did, but I'm not finding it right now. I read somewhere that the flow of air over the shape of a jet plane does funny things when its speed rises too high. I'm taking it that this is purely a matter of the air speed of the plane. I can't get more technical because I don't know the language. But it made me wonder what happens when a plane is cruising at an optimum speed and encounters headwind. Does that raise the effective speed of the plane and subject it to stresses unless the ground speed is reduced? I don't know if this plane, AF447, could have encountered unexpected headwinds. I know they were doing some "open field running" due to some very high storm systems. So it seems possible if they ran into a rotating air mass, they could change directions of wind they were encountering.

I don't want to take this anywhere until someone clarifies the basics.

Winds really have nothing to do with airspeed. If your doing 300 knots airspeed. and you have 100 knot headwinds your ground speed is 200 knots. Say the wind suddenly changes to a 100 knot tailwind. You are still flying at airspeed of 300 knots, but the ground speed with go from 200 knots to 400 knots.

All speed limits, setting are done with airspeed not ground speed. Ground speed is more for navigation.

For example... Our APU exhaust door has a flight restriction of 225 knots airspeed. So as long as we dont go above 225 knots airspeed we can fly all day long. No matter if we are doing 200 knots or 500 knots groundspeed.

[Jason]

The reason I asked was your initial quote:

The only possible scenarios that work for me are an extended (deep) stall (nerly impossible); a normal spin; a flat spin (unlikely); and a long period where the aircraft is in and out of control as the pilots fight to regain control after losing it. I am open to any other possibilities, but I can't see any more.

and then your reply

Zero.

with which I fully agree. I just wondered why you initially worte about possible scenarios which you doubt in the other post

[Leightman]

I see. I wasn't clear enough. I mixed up two concerns I'm trying to keep in mind, the first being how did they get down without overspeeding if they were out of control, and the second was how they might have transitioned to a nose up impact. My first answer with the four scenarios was about how they might have made the long descent. Is that clearer?

[Gabriel]

Thanks Kiwi. I realize Airbus may have a different trigger, the CPC system may work differently, and that your background is Boeing. However IF there is even a rough correlation between cabin altitude and aircraft altitude, the message suggests that the full stall did not occur til at least the time of the message which was at 02:14:26 (and that all of the previous descent was less than 1800 fpm. This of course rests on 02:14:26 being a fairly accurate time. But if true it suggests AF447 made the great majority of its descent without overspeeding (at least to the point of airframe failure) AND without stalling. Given the length and speed of the descent, that is a miraculous margin to have maintained.

And also impossible in only 4 minutes 30 seconds (from 02:10 to halfway through 02:14). You would need 8000pfm avg to descend in that time frame. So something about this data or these assumptions is wrong. Even if AF447 flew toward the ground and used speed to descend (400 mph= 35200 fpm), the average rate of descent would still need to be 8000fpm. That's a conundrum for me.

There are two pages after your post that I have not read yet, so maybe this was answered before. So sorry if this was already answered.

I think you are confusing the different terms.

First, remember this: cabin altitude is NOT an altitude (i.e. it is not the vertical distance from something to something else). It is a measure of the absolute pressure inside the cabin, in a funny scale marked in feet. The cabin altitude is the answer to "What altitude should we be flying to have the same pressure we have inside the pressurized cabin now if the airplane was NOT pressurized?" Confusing, uh?

For example, just for the sake of the argument, say that the plane was flying at 35000ft with a cabin altitude of 7000ft.

This means the pressure inside the cabin is the same that you'd have at 7000ft if not pressurized.

If the cabin is not pressurized, then the cabin altitude and the airplane's altitude are the same. For example, to have 7000ft of cabin altitude unpressurized you have to fly at 7000ft of real altitude. Or if you are flying at 35000ft eith a cabin altitude of 7000ft and then the cabin went suddenly unpressurized, the cabin altitude would quickly "climb" to 35000ft too (not that "climb" here is figurative, since the cabin would not move an inch vertically, but the pressure inside the cabin would diminish as if the plane was quicky climbing unpressurized from 7000ft to 35000ft of real altitude).

Second, remember this too: Higher altitude, lower absoulute pressure. True for both the "fake" cabin altitude and the "real" airplane's altitude. That means that the pressure inside tha cabin is lower with a cabin altitude of 7000ft (when the plane is at 35000ft) than with a cabin altitude of 0ft (say with the door open at the gate).

Third, wait a minute. Does the above means that the cabin is less pressurized with the plane at 35000ft than with the plane at the gate?
No. The fact that the pressure inide the cabin is lower doesn't mean that the plane is less pressurized. The level of pressurization is measured in terms of the difference of pressures, inside vs outside, called differential pressure. At the gate, the cabin altiude and the airplane's altitude are both 0ft, so the pressures inside and outside the cabin are equal and hence the plane is not pressurized, even if the pressure inside the cabin is higher than with the plane at 35000ft, because there the cabin altitude will be "just" 7000ft. And since more altitude equals lower pressure, the pressure inside the cabin will be higher than outside (the plane is sort of "inflated", i.e. pressurized).

Now, the pressurization system is designed to:
- Keep a high enough pressure inside the plane (cabin altitude low enough) even at cruise altitude to let the occupants breathe without using suplemental O2 (the max cabin altitude allowed at the airplane's certified ceiling is 8000ft).
- Keep the rate at which the pressure changes inside the cabin low enough to prevent the ears from popping, that is keep low cabin vertical speeds (which again are NOT real vertical speeds, just a measure of the rate at which the absolute pressure changes inside the cabin).
- Keep the differentical pressure within limits. The fuselage is designed to be pressurized inside out, so the pressurization limits are higher for the possitive pressurization (several psi) than for the negative pressurization or vacuum (barely below zero psi).

Now, say that to achive this the logic of the pressurization system is to keep the cabin altitude equal to 1/5 of the airplane's altitude (this is not in fact the logic, but it's good to match the 35000ft/7000ft of the example we've been folowing).

In that case, the vertical speed of the cabin would be also 1/5 of the real airplane's vertical peed. That means that 1800fpm of cabin vertical speed would equal 9000fpm of real airplane's vertical speed.

It takes less than 4 minutes to go from 35000ft to the sea at that vertical speed.

So, as you can see, a pretty high descent rate even from the start is perfectly compatible with the cabin altitude message being trigged "late" during the event.

But even further, the logic of the system is not to keep a cabin altitude at 1/5 of the airplane's altitude, but to keep low cabin vertical speeds.

That means that even if the plane was falling from the sky, the cabin vertical speed would be low.

It was mentioned before whether that would subject the fuselage to an overpresurizaton and air would have to be vented. It's the other way around. As the plane falls at a high real vertical speed while keeping a low cabin vertical speed, the cabin altitude diminshes slowly (and the cabin absolute pressure increases slowly) while the plane's altitude goes down quicly (and the exterior pressure goes up quickly). Since the original airplane's altitude was higher than the cabin altitude (i.e. the pressure inside the plane was higher than outside), this would just reduce the difference between the external and internal presures (airlane les and less pressurized). So no exceptional stress or anything.

But, if the airplane is falling quickly enough, the pressures would become equalized with the plane still at some altitude. Beyond that point in the fall, if the plane keeps coming down fast with the cabin altitude diminishing slowly, the cabin altitude will become higher than the real altitude. That means more pressure outside than inside, or a negative pressurization (vacuum). More sooner than later, the limit of max negative pressurization will be reached, and hence the priorty of the pressurization system will turn from keeping a comfortable cabin vertcal speed to prevent ears' popping to keep the presurization within limits to prevent a fusealge failure. To do that, the system will open some huge valves that will let outer air go in freely, to keep the presures equalized (out vs in), and hence from that point on both the cabin altitude and the cabin vertical speed will more or less match the real airplane's altitude and vertical speed.

If it's true that the plane hit the sea in one piece and without fuselage breach, then I think it's very probable that the above is what happened.
The instant the system swithces from "keep a comfortable cabin descent rate" to "don't let the outer pressure be higher than the inner pressure" the cabin vertical speed (which, for the lat time, it's NOT a real vertical speed) would suddenly go from a low value to a high value. At that instant you would have the "cabin vertical speed greater than 1800fpm" triggered.

Note that this can happen not sooner than when the plane reaches a real altitude equal to the cabin altitude it had at cruise, 7000ft in this example (in fact even lower since the system would have kept the cabin altitude reduceing somehow from the original value during the fall too). So, even if the descent happened at a constant vertical speed of some 8000/10000fpm (as you've said), the majority of the descent would have happened without a cabin vertical speed of more than 1800fpm, but in the last few thousands of feet the cabin vertical speed would have been huge, well in excess of 1800fpm (in fact, matching the plane's vertical speed).

[Gabriel]

Zero. Spiral dive (to me anyway) is an accelerated, nose down stall with taw rotation and increasing speed until things fall apart. Recovery is to unstall the wing/reduce AOA, which is about the last thing you feel like doing right then and stop the yaw-the order depends on the A/C-- and then geently pull out without overspeeding.

A spiral dive is nt a spin (even when the airplane is descending in spirals), has nothing to do with a stall, and the recovery is nothing similar to what you've said.

A spiral dive is simply a dive combined with a turn, with the nose down pitch and the bank angle typicalli increasing.

The unintentional spiral dive is typically the result of spacial dissorientation. The sequence goes more or less like this:

You are flying straight and level with no autopilot. Because of asymmetries, the plane starts to bank very very slowly. As the plane baks more lift would be needed to keep the altitude, but since the pilot in not aware he doesn't pull up, so the nose goes down and the speed goes up. This process increases very slowly, until at some point the pilot notices the increase in the G forces (no, the pilot has not pulled up but the speed is much higher than the trim speed so there is more lift than needed for the 1G flight). At that point the pilot looks at the instruments and notices a high bank & very low nose attitude combined with a dangerously high and increasing speed.

The recovery procedure is to level the wings, not to pull up, let the plane pitch up by it's own (remember it's pulling high Gs by itself) and then push down to prevent the pitch from overshooting (you could even do an uncommanded loop if you don't do that, not very advisable when you are trying to recover after just becoming spacially dissoriented in instrument conditions)

A spiral dive in this accident would be a very reasonable outcome (even the expectable one) if the pilots lost attitude information, but I think that didn't happen. Also it doesn't look very compatible with a flat hit as reported.

[Gabriel]

The only possible scenarios that work for me are an extended (deep) stall (nerly impossible); a normal spin; a flat spin (unlikely); and a long period where the aircraft is in and out of control as the pilots fight to regain control after losing it. I am open to any other possibilities, but I can't see any more.

There is another possibility (don't want to qualify is even as "theory" since I really don't think this happened)

The pitots disagrees, but all three show a slower airspeed. They decide to trust one of them, perhaps there are two that closely match (both wrong).

Anyway, they conclude that they are flying too slow. They increase the thrust, up to max continuous, but it doesn't help. The airspeded keep showing slower and slower (because the pitots are becoming more obstructed). But the plane is flying faster and faster.

Perhaps they see that the outside air tempertarue has suddeny increased a lot. That is not unheard off when there are string updrafts bringing wrm air from below. At a high altitude, with an unusually high tem, the density altitude could be more than the service ceiling, so perhaps they conclude that that's the reason why the plane can't keep speed and altitude at the same time.

In any event, they see that the speed is going dangerously down, approahing the stall speed. To prevent stall, they decide to trade altitude for speed, so they start a descent.

Again that doesn't help. The speed keeps showing slower and slower (with the plane in fact going faster and faster).

They increase the descent rate even more.
At that point they exceed the max speed and suffer a Mach tuck (the tendency, sometimes uncontrolable, of subsonic planes to pitch down when approaching to Mach1 due to the center of lift moving aft).

They don't understant what's going on. The speed is too low despite the ful power and the plane going down like hell, and not it wans to pitch down even more by itself?

At some point, the higher temperature of the lower levelsand the friction with the nearly sonic speed melts the ice, the pitots become unblocked, and the indicated speed suddenly goes up to the real value (not that the ACARS would NOT send a message when the disagree ends). They reduce power and lower the landing gear to slow down, they manage to do it enough to regain control and pull up but just a little too late: They hit the water during the recovery.

Problems with this theory:
- The pilots would not be following the procedures for unreliable speed.
- The pilots would not have learned the lesson from this accident that happened before.
- Where is the overspeed warning when the pitots got clear of ice? That would have trigged an ACARS message I guess...

[P3_Super_Bee]

- Where is the overspeed warning when the pitots got clear of ice? That would have trigged an ACARS message I guess...

Was going to say there wouldn't be one. Its a flight error, not a maintenance issue. Though, I would assume an Over speed Inspection would need to be performed so there might be an message.

[Leightman]

A spiral dive is nt a spin (even when the airplane is descending in spirals), has nothing to do with a stall, and the recovery is nothing similar to what you've said. A spiral dive is simply a dive combined with a turn, with the nose down pitch and the bank angle typicalli increasing. The unintentional spiral dive is typically the result of spacial dissorientation.

The recovery procedure is to level the wings, not to pull up, let the plane pitch up by it's own (remember it's pulling high Gs by itself) and then push down to prevent the pitch from overshooting (you could even do an uncommanded loop if you don't do that, not very advisable when you are trying to recover after just becoming spacially dissoriented in instrument conditions).

Well I better tackle this one first because its....shorter It may well be true there are as many unique flying stories as people, and there's not just one answer. That said, I can't claim a library of spiral dive experiences, nor would I want to. I just have one, with a student at the controls, and its entry, in retrospect, was sooo smooth and unlike any "standard" stall or spin entry I'd been through. It was inadvertent, totally unnoticed, not the result of spatial disorientation, and it was fully stalled with a 30 deg bank angle and about 50 deg nose down by the time I figured out that the damned thing was indeed stalled, nose down, and with all that speed. Recovery was as I said: reduce AOA and unstall the wing, level wings, stop yaw, pull out. Now as YOU said, you CAN just sit back and wait for the dynamic stability that was supposed to have been designed into the plane (and preserved ever since by all well paid mechanics doing flawless work) to lift the nose for you, and there's certainly something to be said for being gentle at that point. But the inbuilt stability is rather slow, and the certification tests passed long ago didn't begin anywhere near redline with a 50 nose down attitude. So one must make a decision to ler the airplane do it gently and fairly slowly, or pull out bit faster (bearing in mind the age of the plane and its g rating) so the downhill sleighride is not quite so long. The push down you refer to happens at the end, when most of the excitement is over, and yes you do have to do that unless you want to go through a bunch of undulations.

I always thought the spiral dive was the same as the "death spiral" written about in blood tinged prose of the 19teens and 20's, but I never had a chance to interview those pilots because they ended up, well, dead.

From that I learned that that all those standard stall and spin entries I practiced were misleading in that they were very different from this one, and it made me want to practice more so I wouldn't get surprised again. The spiral dive is a different animal, just as the inadvertent over-the-top spin entry that is NEVER practiced is quite different, and a fully developed spin is different than the 1/2 turn entry that is usually the extent of what many pilot ever get to experience.

But thanks for brnging that up.

[Leightman]

There is another possibility (don't want to qualify is even as "theory" since I really don't think this happened).......................The pitots disagrees, but all three show a slower airspeed. They decide to trust one of them, perhaps there are two that closely match (both wrong)

I appreciate your effort in this explanation, but I don't know how one could increae to full pwer and then the nose down, and not overspeed. Coffin corner and all that.

But I tend to think you're right that a recovery pullout was initated too low, meaning they tried. What happened to get then down low enough, safely, in one piece is what interests me. And in that sense pitot icing would be a convenient answer. Given a hypothetical entry speed ( say near Vne), and wings level (don't make it impossibly difficult) and a hypothetical set of flight path descent angles, a person with knowledge might be able to calculate an altitude from which recovery was begun.

[Leightman]

Note that this can happen not sooner than when the plane reaches a real altitude equal to the cabin altitude it had at cruise, 7000ft in this example (in fact even lower since the system would have kept the cabin altitude reduceing somehow from the original value during the fall too). So, even if the descent happened at a constant vertical speed of some 8000/10000fpm (as you've said), the majority of the descent would have happened without a cabin vertical speed of more than 1800fpm, but in the last few thousands of feet the cabin vertical speed would have been huge, well in excess of 1800fpm (in fact, matching the plane's vertical speed).

Thanks Gabriel, for your exhaustive explanation. This is exactly what I was looking for and, despite my shaky explanation, what I suspected. I don't recall now but it may have been Kiwi who listed the pressures cabin pressures at altitudes ranging from the ground. So what I suspected (for the wrong reason)--that the pressure differential would accelerate markedly say from 10,000 down to 5000'--is that somewhere between 8000 and 2000' the cabin pressure would depart from its "comfortable" rate of change ( the CPC couldn't keep up) to begin to follow the actual altitude. Cabin pressure was the last message, and I tend to think, without any supporting info other than the cessatin of messages, that impact followed within less than ten seconds.

This again suggests to me is that the pilot's had lost, but then were regaining control (or had gone in and out of control multiple times), but didn't have enough altitude at the end. Something changed somewhere between maybe 6000 and 12000' to allow them to comprehend their attitude and being to regain control, other wise they would have not impacted nose up.

[Leightman]

Airspeed/windspeed

SYDCBRWOD: "I'm guessing here, but if you did fly into a 'sudden' headwing then yes, due to inertia the aircraft would initially experience a higher than usual airspeed, but due to the increased drag, the airframe would quickly slow down to whatever the airspeed was before you encountered the sudden headwing. ...Unless you flew into say the funnel of a tornado I'm guessing that winds don't just stop and start that abruptly...."

P3: "Winds really have nothing to do with airspeed. If your doing 300 knots airspeed. and you have 100 knot headwinds your ground speed is 200 knots. Say the wind suddenly changes to a 100 knot tailwind. You are still flying at airspeed of 300 knots, but the ground speed with go from 200 knots to 400 knots."

There is a distinction missing here and it is one of time, that is, whether we are talking about steady wind where there is a very long transit time between one wind speed and that of the next, or a gust or shear with an aircraft experiencing an abrupt transition. CYD, I agree about a momentary change of airspeed if the airmas changes speed, but the plane will not change speed "quickly". Winds don't just stop and start, but if you are transiting an airmass with strong horizontal flows, the resulting effect of crossing them will be rapid airspeed transitions.

P3 I agree if you are talking wind and not at all if you are talking gust or shear. If you are flying at 100 kts in a two hundred mile wide laminar tailwind airmass flow that is zipping along at 100 kts, you ARE only flying at 100 kts, but your ground speed is 200 kts. But if you are flying at 100 kts in calm air and hit an instantaneous headwind wall of 100 kts (as in a chinook wind) your airspeed will instantly go to 200 kts, and your ground speed will rapidly decay due to drag towards 0. Or if you are on short final and get a tailwind shear of 40 kts you will fall out of the sky. If you are flaring and get a 30 kt headwind gust, you will balloon because your AOA anticipates you decelerating down through stall speed, not increasing speed. Gust or shear are experienced by a transiting object as a rapid change of airspeed, which move closer to being instantaneous the faster the object moves. If you hit a hypothetical headwind wall of air, your airspeed WILL decay due to drag, eventually. Depending on the mass and drag of your A/C (hang glider or A330), that may or may not take some time.

[Tomtom]

Training manual - UNRELIABLE AIRSPEED INDICATIONS

This just on a side note, but thanks to the great link to smartcockpit.com, I found the following in the training manual for A330/340 regarding unreliable airspeed indications.

Although it's not for the -200 model:

http://www.smartcockpit.com/pdf/plane/airbus/A330/misc/0002/

Page 227ff

Most of it we have discussed already here, but the manual does suggest to use GPS to determine speed; GS in this case. IIRC we thought this is too inaccurate due to possible high wind speeds.

However, it doesn't seem the crew got that far unfortunately.

Cheers
Tom

[Theoddkiwi]

I've spoken a lot in the past about the partnership between complex systems and human pilots. On the Turkish 1951 forum, I saw a situation where the system could work against the pilots. Same with Colgan 3407. Also the case with a number of near-disasters, and potentially the case here. That problem has to be worked out from both ends. Systems need to be reviewed for potential situations that could be counterintuitive, misleading or combative to pilots, and pilots need have a more in-depth understanding of how these systems are affected by various factors, failures and conditions. For example, in the case of Turkish 1951, the crew was using the A/T despite being aware that their left LRRA was unreliable. The A/T on a 737NG cannot be used with even an intermittent left LRRA fault, ever. They lacked that understanding, as did their maintenance who allowed it to fly as a MEL item without flagging the A/T inop. The Turkish pilots had no idea their A/T was trying to flare in the middle of an approach because they weren't working in close partnership with the automation (or flying the plane - I know...don't start...)

Sorry to bring up old battles But You CAN use A/T on the 737NG with an MEL'ed Radalt. I very clearly states in the MEL that the onside A/T should not be used on Approach. The maintenance guys have no legal obligation to point this out to the pilots as it is their legal obligation to read and be aware of any known defects with the aircraft and acknowledge and follow any limitations that known and legally defered defect may refer.

If the pilots used the onside A/T with out considering the limitations of an MEL then they have been negligent. Alongside the fact that they stopped flying the aircraft at 2000ft.

I MEL Radalts every other week, our pilots have never expressed any concern with that. They read the limitations and fly appropriately.

[Jason]

Gabriel's theory reminds me very much of the Birginair Crash in 96...

does anyone think that

a.) the CVR / FDR still will be found and

b.) if not the mystery will be solved at all?

[swissair]

Too many gaps

Swissair, I shouldn't lash out at you and I apologize. Let me take a different approach, and try to bring you into the conversation. Please read closely.

First of all, welcome to the JetPhotos.net Aviation Safety Discussion Forum.

What we do here is discuss what may have caused an accident. You've already done that part.

We present evidence to debate our theories. You don't have any, so skip this part.

We keep an open mind. You need to work on that a bit.

Then, (this is where you can come in), this is a constructive forum: we also discuss what may have gone wrong within the aviation industry to cause that accident, where weaknesses may exist in aviation safety, and what we can do about them, what changes or improvements can be made. These can be pilot procedures, system changes, airframe modifications, regulatory changes, etc.

Now, lets assume it was a bomb. I'm sure the investigation has not ruled out that possibility, and I'm sure they have reviewed security at Rio and are scrutinizing anyone that had access to the plane.

How did that happen? What can be done, within the aviation industry, to prevent that from reoccurring?

Since 9/11, the industry finally woke up (despite decades of terrorism) and put locks in the cockpit doors, properly vetted and trained security personnel, installed new baggage screening technology, tightened many procedures to assure that every bag was linked to a passenger and was subject to inspection, and every passenger was subject to inspection as well, recently going to the debatably absurd extent of removing shoes and limiting fluids.

So I ask you now, what more do you think can be done to prevent a bomb from getting on board a plane? Keep in mind basic human dignity and the humiliation that comes with racial and cultural discrimination.

Thank you for opening the dialogue in this direction. The problem with terrorism is that it is a perversly cowardly act, to make the debate simpler and get away from any kind of racial angles here, Terorists are by all means killers. They kill and so called suicide killers in any shape or form are killers, full stop. There are a lot of gaps on the AF 447 here and we all know that. Unfortunately we will always have to live with a risk of having killers aiming at civil aviation. Now in this case we all can observe an obscure reporting by all elements around France, their timing, their initial speculations, there so called interim report. A killers strike can not be ruled out and I wonder what would it take to render an AB330 inop, not controllable, what would be the minimal device be? Not all of the bodies have been found as we know, so we can not say, uh, we have not found any explosive traces or blast marks on bodies, the same goes for the mostly still not recovered wreckage and of course the ace, the FDRs. How come an Atomic submarine with the most sensitive sensory equipment is unable to locate the wreckage, it is also clear that that kind of sub has depth limitations, but its sensors can go wide and deep. We know also that Pitot failures were not the initial cause. ACARS messages lead us all to start calculating and trying to reading them to a possible conclusive result, we were not able to and, I think others mentioned that here before me, why would AF or any airline post crash release such vital data to the media? Or was there an agenda to do so to point in the "wrong" direction. Journalists must print so they can eat, they are not paid to do serious investigative reporting, a few only of those, but mainstream is under pressure to print otherwise a pink slip is on their desk. I also belive that determined killers, if they then would be organized and equied with some cash can if they then really want stll neak through controls. Airports in my view have become a lot saver but at some places where security is overdone, I suspect the routine can provide failure. Worst, Rio is no Doberman pit...like, say, Dulles Intl where we have to take shoes off and depose our a bit too big After shave, or matches that we wanted to bring home as a souvenir etc. I do no know if it is possible to take a step back and filter all again and take the big mostly probable facts and reassemble, maybe prioritize them 1 2 3 style. But then we will find out that all of a sudden 3 becomes 2 and 1 becomes 3 and that is where I smell a rat. Evan, thanks for your patience and I also do never want to offend anyone, sorry if sometimes emotions come out, this one is sad and something went terribly wrong, condolences again for all the families and loved ones of the victims. SR