vakakaaa

210thars picture shows mobile unit PAR-10 with (NDB) P200 medium wave beacon transmitter. Different types of mobile units have been used for decades, in all countries. The “3-prong” refers to 3-element Marker antenna pair, mounted on the side of the mobile unit. Kung (kunga) in English refers to "hard-top" (it originates from military!). The discone antenna at the vagon roof can also be for data link from the mobile unit.

NDB mobile transmitter unit can also include Radio station P-583 B1 for retransmission of ATC- information to the aircraft, it was common in older Soviet systems (ATC talking also on NDB freq via ADF). Also as noted a PRMG marker transmitter (VHF) can be included. Russian AIP GEN 3.4.1.gives emergency frequencies as 121.5, 129.0 MHz & 725 kHz (LOM), 355 kHz (LMM).

ATP and other pilots almost everywhere are no longer so interested in ADF and NDB type beacons but in this 101 case they no doubt should have been very interested for their safety.

PRMG 5 and other PRMG types is a different story with its course and GP antennas located elsewhere around the airport. NVA-Flieger site gives a good summary about the complex system (SP-1) having been used in Soviet/Russia, DDR etc. As Arrakis also above mentions the PRMG system apparently was removed from the XUBS airbase when the Il-76 unit was disbanded. What about RSBN?

But the 3-element Marker antennas (they go in pairs) shown pointing up in 210thars picture are actually a part of PRMG landing system.

210thars : Signal at F=800 Hz. Inner marker = "near БПРМ" beacon ident audio "O" (on 640 kHz) from ADF

SadPole

One more thing to remember is that whatever the hell the crew was trying to do, they did the whole thing on Tu-154 autopilot. Yes, some spoken info might have been distorted on the CVR, but there is very little chance that the autopilot sound signals were not recorded and recognized clearly.

So yes, while some can fantasize that the CVR has been tampered with, I will assume that it was not, at which point we arrive at following facts:

• The autopilot was NOT disengaged till 10:40:59 or 5 seconds before the plane came in contact with trees
• The autopilot was in control all the way until after the navigator read 20 meters as altitude.
• The only major intervention into the autopilot might have happened at 10:40:51 when the 2nd pilot issued the goaround command and therefore possibly changed the autopilot mode to goaround.
• As far as I could tell from available documents, entering the goaround mode does not result in any specific sound signal being emitted.
• The Tu-154 radar altimeter clearly has means to set altitude and they are on CVR setting it to 100 meters. And yet, no alarm sounds till they are at around 70 to 60 meters
• Note, however, that this alarm sounds right after the 2nd pilot possibly placed the autopilot in the goaround mode. Why? Is it perhaps that (as I suspect) they stupidly were flying on that radio altitude hold "ground hugging" mode.
• It appears that after entering the radio altitude hold mode, the autopilot will drive the plane into "locking" onto entered altitude and no sound signal is issued after it happens, only the H button will light up when the target altitude is reached.
• However, if the autopilot is switched into the goaround mode, the radio altimeter is no longer used as the control signal, at which point it would sound the alarm if the plane was below the entered value of radio altitude, and this is exactly what happened per CVR.

Please note that it isn't too unlikely that the Tu-154 crews got used to using that H hold autopilot mode even if they did not understand completely what it was for. As in: enter the "decision height" as the target radio altitude and let the autopilot fly the plane down to that height and lock into it. It would work at every airport that has 1000-2000 m reasonably flat terrain before the airport. One problem that I see with that procedure is that regardless of terrain, the descend path is got to be pretty steep if the purpose of that mode was "ground hugging" and not safe landing. The other problem is that if you do ground hugging toward a cliff, it is not going to work out too well. (See Tu-154 crash pictures).

ARRAKIS

Quote:

The Tu-154 radar altimeter clearly has means to set altitude and they are on CVR setting it to 100 meters. And yet, no alarm sounds till they are at around 70 to 60 meters

As it was set later to 60 m.

Arrakis

SadPole

Quote:

As it was set later to 60 m.

1. Where/when did they do it? (It is not in the transcript)
2. Why would someone do it without loudly communicating it to others?
3. Why would something like that be done without any discussion?
4. If the the autopilot was not on the H-hold mode, what mode was it in?
5. How did they get so low without monitoring instruments?
6. Why would the dangerous altitude sound 0.3[s] after the 2nd issues the goaway command? Probability of coincidence is almost NONE here.

BOAC

I also do not see this 'setting' of any minima on the CVR I have seen - can you please give me the time?

ARRAKIS

A RA - here a RV-5M - doesn't generate a 400 Hz warning sound some 30 m too late. I know that one quite well. If we have a sound at 60 m, it means it was set to 60 m.

As I wrote before, 60 m would be exactly the setting according to Tu-154M FM.
Cross-checking the transcript with the Tu-154M FM, the "before approach" checklist is missing. Not a word spoken.

Arrakis

SadPole

10:10:07,6 Navigator: RV, settings. RV.
10:10:10,6 PIC: 100 meters,

The confussion in some translations comes from transition from cyrylic to latin or taking Polish acronyms RW and then placing them in English translations.

P - Russian 'R' as in Radio
B - Russian 'V' as in Vysota (altitude)

The official transcript correctly translates it into Polish as RW (Radio Wysokosc) (Radio Altitude)

Anyway. the Tu-154 radio altimeter is (Russian spelling) RB5 with translations into English designating it as RV5 instead of RA5. (Complete mess with letters as you see - 5 different people can use 5 acronyms).

SadPole

Can you, however, confirm or deny that the ABSU would sound any altitude related alarms when it was set in H-hold mode?

Or, that it would not sound alarm at 60meters when ABSU was given the goaround command when being at 60meters while finding itself at 60m while doing H-hold set at 100m?

ARRAKIS

What you are quoting, is a part of "before descent" checklist.

Personally, I don't have any problems with RW/RV/PB.
In English, we should use "RV".

Nope. RW stands for radiowysokosciomierz = radar alatimeter.
The same mistake for the Russian PB/RV.


Arrakis

BOAC

Thank you SP - I did not know what 'RW' was. Still odd (and incorrect) to set a radalt minimum. I had assumed they were discussing approach mimima for the RunWay. Has 'Wt' been identified yet?

Apologies if I have missed it, does anyone have a chart for the Smolensk 2xNDB approach?

SadPole

And it is different how? Because you added -mierz (meter) to the name and I did not? Maybe I have been using English too long, but generally in English it is no sin to shorten words if meaning is not changed.

And yes, that PB5 thing has a clickspot for setting altitude that is an input to ABSU while no baro alt is fed to ABSU.

SadPole

You mean the WN-y they talk about at 10:09:47?

In all the Polish discussions I have seen it is claimed to be the TU-154 EIDS deicing.

ARRAKIS

There is quite a difference between radio height and a radar altimeter.

BOAC

XUBS1.jpg | arrakis | Fotki, Zdj?cia, Obrazki Fotosik.pl

XUBS2.jpg | arrakis | Fotki, Zdj?cia, Obrazki Fotosik.pl

XUBS3.jpg | arrakis | Fotki, Zdj?cia, Obrazki Fotosik.pl

There were some changes since 2006 (see transcript).

Arrakis

RetiredF4

BOAC

SadPole - from the Polish transcript I have kindly been provided with:
Osoba oznaczona jako Wt (małe t) nie opisana w legendzie (legendzie na stronie 40)

Arrakis - thanks very much. I would appear that the crew had decided on a 3 degree slope rather than the published 2.4? This does not put them 'high' at the outer marker. Where the 'on course on glideslope' comes from, however?

You can see the NDBs being set at 10:30:00

SadPole

Oh, now I got it . More letter confusion. That 'W' thing is a Cyrillic Russian letter that is read as 'sh' and in this case this is Shturman (navigator).

If someone is copying a latin transcript where that 'sh' thing is replaced by W, it is completely wrong. They should say 'sh' as is common practice or guess that it clearly means navigator.

Штурман

ARRAKIS

BOAC,
those are cards from 2006. If you compare them with MAK's information and the transcript, you will see that Tu-154 was flying it's approach on the 259 course. The old card gives 261. We don't really know what other changes were made.

Arrakis

BOAC

That is simply what we call the change in 'Magnetic Variation'. I suspect nothing has actually changed.

Fox3WheresMyBanana

Forgive me guys, as I am guessing a bit since I don't have a complete, correct English translation of the CVR. Are we now suggesting that:
1) They were probably set up for an autopilot 2-NDB approach, 3 degree glidepath, with the MDH set on the Radalt because the autopilot won't take Baro Alt inputs?
2) That they probably were using the talkdown for clues, and we're not sure why the talkdown was wrong?
3) That because of the above 2 points, no-one on the flight deck was properly clued in to what the expected rate of descent should have been, and/or they weren't cross-checking it properly.
4) At the last gasp they forgot they were on radalt not baro alt, or they didn't know about the ravine?
I would much appreciate 2 minutes of someone's time to get me back on the thread here, thanks.

Karel_x

sadpole:
1. Where/when did they do it? (It is not in the transcript)
It is not recorded on CVR
2. Why would someone do it without loudly communicating it to others?
All approach looks very non standard, like improvisation
3. Why would something like that be done without any discussion?
There is significant lack of in cockpit crew communication in this case / not existing 4 members crew procedure and lack of expirience of them/
4. If the the autopilot was not on the H-hold mode, what mode was it in?
Klich told pitch stabilization mode
5. How did they get so low without monitoring instruments?
Ony heavens know - improvisatins, stress?
6. Why would the dangerous altitude sound 0.3[s] after the 2nd issues the goaway command? Probability of coincidence is almost NONE here.
I do not understand your question - why it could not be a coincidence