Polish President and wife killed in Tu-154 crash

[Evan]

According to the CVR transcript the altitude numbers were read by the navigator.

Oh right, the old 4-man operation. Does the navigator sit behind the pedestal, facing the forward panel?

[Northwester]

This is how they sit.

[guamainiac]

You just gave me a vision of a "technical malfunftion".

They pointed searchlights towards the runway?

Wait till a foggy day and find a friend with a car with real driving lights. Old fashioned "Lucas Flamethrower" type and have them turn them on in the fog.

Even fog lights don't work in fog. Car and Driver and Road & Track have been conducting tests on real fogs for ages and have never come up with one that really works well.

Perhaps they emerged to a confusing and blinding back scatter of light. There, perhaps is the making of a disaster.

The Polish government could test this (to a point), under controlled conditions. True, no two "fogs" are identical.

[Northwester]

Really? It is now your contention that either the pilots mistook some spotlights for the runway, or there was a mechanical problem? It's either A or B? I don't think so. And that's a far cry from where you started on this thread looking for some opinions based on hard facts; instead, you've arrived at the Mistaken Runway Theory with scant evidence, and it is a theory apparently full of holes. I see no reason to discount Evan's original characterization of this as a tree-top hunting expedition. They were hoping for the best, and maybe not quite prepared for the worst. Does it all add up? No, but assuming this was to some large extent a case of human error, I wouldn't expect it to. At some point, the pilot's judgment broke down, and trying to impose logical responses to what he did after the fact is not necessarily going to work. Nor will we ever be able to get inside the pilot's head to know what he may or may not have been thinking. Hence, without someone having said the runway is in sight to offer as evidence, your theory will forever remain mere speculation.



Unfortunately, that seems to be exactly what they did, since it's unlikely they ever saw the runway, and they definitely descended to the ground.

You only go that low if you cannot control the plane, you think you see the runway, or you think you are much higher and have room to descend. If you decide to bust the minima, you might in a stupid way descend to maybe 50m, but if you still don't see anything, you get out of there very fast. They knew how high they were. When the navigator said 20 and they were still descending that's not busting minima.

[Northwester]

You just gave me a vision of a "technical malfunftion".

They pointed searchlights towards the runway?

Wait till a foggy day and find a friend with a car with real driving lights. Old fashioned "Lucas Flamethrower" type and have them turn them on in the fog.

Even fog lights don't work in fog. Car and Driver and Road & Track have been conducting tests on real fogs for ages and have never come up with one that really works well.

Perhaps they emerged to a confusing and blinding back scatter of light. There, perhaps is the making of a disaster.

The Polish government could test this (to a point), under controlled conditions. True, no two "fogs" are identical.

Remember, the fog was probably about 50m above ground. Those powerful lights worked well to brighten the area and indicate the runway. If they were in the right place.

[guamainiac]

The thing that still bothers me is that this, like many accidents, have a smattering of the "Thurmon Munson" effect. You need to stay ahead of a jet aircraft much more than a prop. With a prop, you get almost (note almost), instant lift when you apply power but with a jet you have to allow spool up time before the thrust will provide lift. It also sounds like he was way behind the aircraft or, was committed to landing.

How much fuel he estimated to have been carrying and would it have been sufficient to reach his alternate?

[guamainiac]

Now my question (50m above), would go, was there a potential for the lights to have illuminated a "laminar" layer or been reflected and diffused in some confusing fashion. Granted, optics are miles beyond me, but that is a question that perhaps should be answered?

[Evan]

This is how they sit.

You are missing the navigator in that photo. The empty seat in the middle faces the nav computer readouts.

There are three altimeters (not including the standby) on the Capt's forward panel. One metric baro coupled to a static port; one in feet, electric and not coupled to a static port; and one radalt:

Altimeters
On the captain's side:
UVO-15 metric altimeter (105). On the bottom there isa hotspot to enter the baro pressure (in mm Hg ), displayed in the tape window underneath. 1013 hPa is 760 mmHg.
UVID-15 feet altimeter (117). The device is not connected to the SVS (static pressure system), and has its own hotspot to set the pressure (in inches Hg) and the pressure display window. Used to set a separate pressure since in the CIS you will get the pressure in QFE (so the altimeter reads 0 at the aurport) and QNH abroad. Must be switched on separately using the switch on the overhead (403)
VM-15 metric altimeter (11. Standby UVO-15, works from the SVS, has no pressure input.
Radio altimeter RV-5M (116). Has a hotspot to enter decision height, when at DH the yellow "H" lamp will illuminate and the "H" placard on top of the captain's annunciator panel will engage. Also an aural warning (long low-pitch beep) will sound. The instrument readout depends on roll and pitch of the aircraft. Enabled using switches 425, 426 (left and right). In this model, the copilot's radio altimeter is slaved to the captain's.

Tons of detailed tu154 cockpit info on this sim model site:

http://yurik.flightgear.ru/tu154eng.html

THis particular plane had a very recent avionics upgrade, so I would expect a digital radalt somewhere, probably in the same RA bay, but perhaps the entire layout is different.

I'm just wondering if the navigator is trained to read from the radalt or the baro alt on final. The pilot may have been ignoring baro and watching the radalt... and feeling very confident that he could keep his job.

[Gabriel]

With a prop, you get almost (note almost), instant lift when you apply power but with a jet you have to allow spool up time before the thrust will provide lift.

Really? When did power and thrust started to provide lift?
Speed does.

At Vref you can transition from approach (descent) to go-around (climb at some 15 deg nose up) immediately, without waiting for the engines to spool up. Sure, you'll loose a couple of knots in the process as you wait for the spool-up, but Vref provides for that. And the spool-up lead-time is not that bad at normal approach thrust settings.

Now, if you are making 2600fpm instead of 750 you'll need a lot less than normal approach thrust to keep the speed, and the spool up time would be quite longer. And there are hints that perhaps they were not at Vref but slower.

Too low altitude, too high descent rate, too low speed and too low thrust. That's a terrible combination to start a go-around.

How much fuel he estimated to have been carrying and would it have been sufficient to reach his alternate?

Yes, according to what the captain said, they could circle for half an hour and then go to an alternate.

[Northwester]

How much fuel he estimated to have been carrying and would it have been sufficient to reach his alternate?

They had enough fuel to go to an alternate, about 11 tons left.

[Gabriel]

... one [altimeter] in feet, electric and not coupled to a static port...

And how is it supposed to work?

I know three types of altimeters:
- Barometric
- Radio
- GPS

[guamainiac]

Note the word almost and dang, I knew Gabriel was going to go there but did not feel the need to be that precise.

Gabe, you know the basics and it takes a lot longer in any jet to establish a positive rate of climb when you pop the throttle forward. Where does the speed come from? Nose down or thrust and prop is faster.

I figured that by the reference to Munson, you would know where I was going with this. Munson was a catcher for the Yankees and was flying a Citation.

One of the jet folks can comment on the time difference (for the actual difference) but, it is marked and not a minor issue.

[Gabriel]

The searchlights were directed towards the runway. At 10:40:56.0 the first reaction -trying to pull up the nose. At 10:40:56.6 they apply full thrust. At 10:40:57.9 the last part of auto is off - they try to turn.

Where did you get all this info?
Especially the "trying to pull up" and "trying to turn" parts.

[Evan]

And how is it supposed to work?

I know three types of altimeters:
- Barometric
- Radio
- GPS

No idea how an electrically powered altimeter works. Some kind of Klingon technology. Here's what it tells me:

UVID-15 feet altimeter. The device is not connected to the SVS (static pressure system), and has its own hotspot to set the pressure (in inches Hg) and the pressure display window. Used to set a separate pressure since in the CIS you will get the pressure in QFE (so the altimeter reads 0 at the aurport) and QNH abroad. Must be switched on separately using the switch on the overhead

[Gabriel]

Gabe, you know the basics and it takes a lot longer in any jet to establish a positive rate of climb when you pop the throttle forward.

The ONLY reason for that is that, in a normal approach, the descent rate in a jet is much higher than in a C-150.

Leave the throttles at a side, please.

In both, if you are flying at a proper approach speed you can extract say 1.2 Gs from the wings. 1.2 Gs is the same rate of change of vertical speed in a C-150 and in an A380 at MTOW. Except that the A-380 will have much more sink rate to kill.

As a side note, the reason why the descent rate is faster is because the approach speed is faster (at the same slope angle, more forward speed means more vertical speed).

And the reason why the approach speed is faster is not that the weight is heavier, but that the wing load is greater. It's not that the airplane is big and heavy, but that the weight growed faster than the the wings.

And finally, none of these have something to do with the throttles, the power, the thrust, the engines or the spool-up time.

Of course, once a positive rate of climb is established, you better get some thrust from somewhere fast, because otherwise you'll be trading speed for altitude and you don't have much more speed to give. But that's AFTER you established a climb, not FOR establishing a climb.

Again, the key factor here are not the weight, not the thrust, not the spool-up time. But the speed (which seems to have been too low) and descent rate (which seems to have been way too much). If you don't have speed, THEN you'll need thrust or altitude to get speed before you can pull-up, and additionally if you have a long spool-up time (which gets worse if the thrust is below normal approach settings) you'll need time (i.e. more altitude) for the engines to deliver.