RUSSIAN AIRPORTS HAVE TWO NDBs, WHY?

[bluehawaii]

Does anybody know why some major Russian Airports have two NDBs on the final approach course. One NDB located at outer maker position and the other located at inner maker position?

[Exaviator]

They are there for the old style Twin Locater Approach. Not seen much these days at Western airports but the Ruskies are known to be a bit behind the times. :hmm:

[BOAC]

..........and if you are going to have to fly an NDB approach, the IM beacon is extremely useful and makes for a far more accurate line-up. This topic has come up on the Tripoli crash thread too.

[Tmbstory]

It is part of their instrument approach procedure. If you use it correctly, it results in a safe and orderly arrival.

Tmb

[eckhard]

If you have two ADF receivers and two needles on the RMI (or even RBI), the only time the two needles will line up with each other is when you're on course. This is especially useful during final approach when you are between the two beacons; any course deviation will show up immediately as a 'splitting' of the needles. This feature makes NDB tracking a lot easier, especially if you only have an RBI instead of an RMI.

At the close ranges involved, most of the bearing errors that ADF can be suspect to will not be that important. Even quadrantal error will be negligible, as the needles are on the nose or tail. Small bank angles once you are lined up will minimise 'dip'.

[bluehawaii]

Thanks Guys and Gals for your input!:ok:

[Grum]

That's good but when do you start descent?

I'm afraid I can't find the option to attach the Jepp chart but Vnukovo 2 NDB rwy 24 (11-4) as an example.

Your platform height is 1321'. By the time you cross the first NDB (OM) you should be 771' but there is nothing to indicate when to start down. You are given the NDB glide angle and it even gives two different MDH's depending on whether or not you have a FAF or not. But where is the FAF?

Tower will tell you when you are 8km from threshold, is this your FAF?

[Dan Winterland]

Often still seen in China as well.

[411A]

I'm afraid I can't find the option to attach the Jepp chart but Vnukovo 2 NDB rwy 24 (11-4) as an example.


Find someone to attach the relevant chart and you might find the answer.

[bluehawaii]

411A, I have tried to attach the ILS or 2 NDB RWY 24 Approach plate, but I don't know how to attach it to the Thread. After selecting the insert image it is asking for the URL of the image. I have it scanned it to a PDF file, and I don't know how the send it to a URL. Do you?

[411A]

Do you?

NO, ask in the internet section, and you will receive the answer.

[Gulfstreamaviator]

You need to "print" to a file or "ghost printer", A utility like PDF print or similar, which produces a PDF from a image or word doc is needed. I think the latest office version has the option to produce a PDF.

Then treat as any other type of attachement.

just my 1/2 crowns worth.

glf

[BOAC]

BH - I'm not sure you can post a pdf here. Scan the plate to an image file and follow my guidance here (http://www.pprune.org/aviation-history-nostalgia/203154-image-posting-pprune-some-tips-you.html)

[Gear Operator]

I only had a short look, maybe the controller tells you when to start the final descent? This is/was a temporary procedure in MSQ when the VOR/DME and ILS were unavailable and we had to fly the 2 NDB procedure some time ago, where normally the FAF is defined by a DME distance.
Another useful feature of Russian NDB's is that on both sides of the runway they have the same frequency but different ident, so you can determine the runway in use pretty far out.
http://i1004.photobucket.com/albums/af167/Liftdumper/VKO11-4.jpghttp://i1004.photobucket.com/albums/af167/Liftdumper/VKO11-2.jpg

[BOAC]

Loads of discussion of this on the 'Polish President's crash at Smolensk' thread. It appears that as well as a recurring rectangular positioning pattern the USSR seems to use ATC as a descent initiator on these approaches, although we (the west) could fly them very easily 'our' way, intercepting the FAT, commencing descent at that point and observing the 'not below' at the LOM - although you would need to be visual before then.

[Gear Operator]

(...) although we (the west) could fly them very easily 'our' way, intercepting the FAT, commencing descent at that point (...)In my company's case we cannot, because most of the time the FMS goes ' IRS ONLY' long before that due to lack of VORs in Ukraine/Russia and we don't have GPS, so we have to fly (2) NDB aproaches raw data, they're not even programmed in the box either.

What wonders me every time again when we have to fly an ILS as well is that you only know whether you intercepted the correct glide is when passing the OM, not when leaving the initial approach altitude. Although most of the time, when you report established, the controller confirms this by stating your distance to treshold (in KM) and that you're on glide and on track.

Sorry for the off topic content.

[BOAC]

In my company's case we cannot, because most of the time the FMS goes ' IRS ONLY' long before that due to lack of VORs in Ukraine/Russia and we don't have GPS, so we have to fly (2) NDB aproaches raw data, they're not even programmed in the box either.- um? That is how you do fly an NDB approach, is it not? We are not talking 'RNAV' here, just old-fashioned needles. Are you saying you cannot do that?

Any false capture on an ILS (without DME) is normally quite safe until the OM (except the plate posted here for VKO where you would be below the NDB minimum).

[411A]

Looks rather straightforward to me.

Cross xxx bearing of the LOM (OB or GG, depending on the landing runway) at the respective indicated altitudes.
A typical stepdown procedure, just referenced to an NDB.

Common in Russia, from what I've noticed.

[Gear Operator]

Ofcourse we fly NDB app approaches the 'old fashioned' way, but we cannot determine (reliable) the FAF by means of RNAV.

First of all because the FMS is not accurate enough when there's no VOR/DME around and it hasn't the procedure coded in it.
Secondly most of the time Jeppesen doesn't publish the coordinates (in Russia), so even if the FMS is updating it's position by VOR/DME we wouldn't have a clue where the FAF is (VKO example). It would theoretically be possible to calculate it with the descent angle and define it as a place/bearing/distance from the OM.

[BOAC]

Why exactly do you need a FAF?

[411A]

Why exactly do you need a FAF?

That is what I was wondering.
Plenty of non-precision approaches where you don't have any....and none is required.
Even today.:rolleyes:

[Tinstaafl]

It looks to me that it's not much different to doing a standard teardrop NDB approach or, even better, a racetrack entry. Start descent on final once the inbound track is within tolerances (eg 5 deg in Oz but in this case whatever the Russian's specify for their procedures).

[411A]

It looks to me that it's not much different to doing a standard teardrop NDB approach or, even better, a racetrack entry. Start descent on final once the inbound track is within tolerances (eg 5 deg in Oz but in this case whatever the Russian's specify for their procedures).

Yes, agreed.

[Tinstaafl]

That chart depicts two approaches - an ILS, and the Twin NDB. What I find interesting is that LOC only isn't allowed but they're quite happy to use the less precise Twin NDB along the same track.

[BOAC]

.....and as for the DA on the NDB - is it worth it?

[Grum]

Thanks for inserting the charts.

Don't agree with why this procedure should be so simple. I'm trying to see this using only ADF onboard, no GPS etc.



Cross xxx bearing of the LOM (OB or GG, depending on the landing runway) at the respective indicated altitudes.
A typical stepdown procedure, just referenced to an NDB.


You can cross each of the QDRs from the NDB at 1mile or 20 miles from the beacon. Makes no difference to your indication except it'll take longer to travel between each QDR at 20 miles. Regardless of that, you can still use the QDRs at 20 miles to guide you onto an intercept of the final approach course. Now you are established when will you chose to leave 1313' height to descend to the 6 or 700' height required when crossing the OM? This is my point. You could be on a 20 mile final and descend to 771' height and wait a few minutes to cross the OM at said height.


it's not much different to doing a standard teardrop NDB approach or, even better, a racetrack entry.

Well a standard teardrop or a racetrack you start overhead the beacon so you know where you are, then using times and rate one turns you still know where you are. As I said you could join the down-wind leg of this procedure at any distance from the beacon, with a racetrack you will always be within the protected area of the procedure.

I know I don't need a FAF, I want to know when to start the final descent to achieve OM at 700 odd feet and continue to land. I think it must be the call from tower. They do not tell you when to descend, just simply '8km from touchdown'.

Anyhow just curious. BTW, great tip about using NDB ident to determine rwy in-use.:ok:

[BOAC]

Grum - first of all, we understand from the Smolensk thread that it is 'SOP' for ATC to control the pattern and instruct descent. All WE are saying is that in the 'good old days' before LNAV/GPS/FMC WE would
1) probably have an idea where we were in relation to the NDB by watching the needle move
2) if not, there would be other beacons en-route and WE learned to know roughly where we were
3) in the event of all the above turning to poopy, homing to the NDB, flying a rate 1 turn onto the outbound would put you damned close to where you needed to be
4) even if you were 20 miles out when you started descent you
a) should know or might not be in the cockpit
b) in all probability would be terrain safe
Except I have no idea which 'chart' with 1313' and 6/700' you are talking about:)

I expect someone to ask how you could track the downwind leg without IRS/LNAV......................................

[Tinstaafl]

The procedures depicted show lead bearings for base & final turns. Looking at the base turn LB it's fairly similar to what one would expect prior to turning inbound when doing a 1 min hold so the downwind/outbound spacing must be reasonably close. Given that no specific distance or tracking method is defined then spacing mustn't be too crucial. Say, similar to holding pattern accuracy. Like BOAC said, use a sensible way to position yourself outbound such as rate 1 turn after flying over one of the NDBs (that seems what's shown for the missed approach to have another go) or vector onto downwind if available.

Each of those position lines also have an altitude limit, judging by the different forms of box marking; some not above, some not below . Looking at RWY24: Be not above 2650 crossing 304 deg (MSA is 2400') and start the base turn, 2320' crossing 253 deg and start turning onto final. Not below 2000' until established on final (the alt. limit directly on the inbound track). The profile view also shows 2000' until established on final. Thereafter descend to the MDA - just like a teardrop NDB or VOR approach (with descent limits at the LOM & IM).

All the above is based on interpreting the chart using my familiarity with various Western charts. Somewhere in the Russian documentation (AIP, AIM or equivalent) should be instructions about how their charts should be read.

[Grum]

You are both right, I am reading too much into this. I struggle to get the discussion going at work. I should have mentioned that we were radar vectored onto a 15 mile final for 2NDB 06 the other day and cleared for approach. It was VMC but it just got me thinking, would they do that in IMC (probably) and how best to fly it.

The 1313' is the platform HEIGHT on rwy 06 and 693 is OM crossing HEIGHT


Anyway time to read the Polish thread. :ok:

[BOAC]

Aah! QFE - sorry - dull day!

Regarding 'when to descend', I agree 15nm is just a bit too far even for 411A:) I guess if you were radar vectored you could ask for a range - say 8, or time it from 15?

[galaxy flyer]

If on 24, watch for the giant prohibited area at 12 o'clock on downwind--Moscow. The turn to base puts one rather close, too. I'm not sure what Putin's Finest might do to someone overflying the city and I have no desire to find out.

GF

[Tmbstory]

Galaxy flyer:

I liked your comment in post No: 31.

In the past when operating in Far Eastern Russia, if you were alert you would see the "SAM" missile sites tracking you ( for practice ) as you approached the aerodrome.

A reminder of times past, it also kept you on your toes!.

Tmb