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UK NDB only timed approaches

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UK NDB only timed approaches

Old 19th Nov 2020, 18:48
  #61 (permalink)  
 
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In the UK at least the fallback for GNSS is intended to be twofold. a network of VOR/DME stations and a network of DME stations. The first is already in place, it's a subset of the original VOR/DME network, and is intended to support RNAV5. The latter is not yet in place, the UK has plenty of DMEs but they are concentrated in the South and not spread evenly across the country, but will support RNAV1. The limitation for most users is going to be suitable equipment in the aircraft. Multi constellation is likely to be much cheaper and more widely available, even my mobile phone can do that, than boxes which do DME/DME.
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Old 19th Nov 2020, 19:09
  #62 (permalink)  
 
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But was there any plan B on any NDB approach if/when the NDB should fail?
Yes there was Jan, it is called Very high frequency Direction Finding (VDF). The pilot transmits (VHF) requesting either a: QDM = magnetic track to the station, QDR = magnetic track from the station and QTE = true bearing from the station (usually used for chart plotting), triangulating bearings from a number of stations could be made. The VDF let down is when the pilot once over head from the series of QDMs turns onto an outbound track for a given time whilst descending and the track maintained/corrected by obtaining a series of QDRs, then turns inbound on a given timing, continuing to receive bearing from ATC (now QDMs) whilst descending to the procedure minimum height (MDH). This procedure was available for many years after the NDBs became in use so could be a backup. The military used QGH, the difference being that the controller calculated revised heading corrections from the pilot transmissions and also instructed the pilot when to descend in accordance with the procedure. VDF bearings for homing is still available from many ATC aerodrome stations.

The ADF was so named because it dispensed with the controller pilot interaction and therefore was considered 'automatic'. Both methods were usually available at a ATC aerodrome.
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Old 19th Nov 2020, 19:17
  #63 (permalink)  
 
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Originally Posted by eglnyt View Post
In the UK at least the fallback for GNSS is intended to be twofold. a network of VOR/DME stations and a network of DME stations. The first is already in place, it's a subset of the original VOR/DME network, and is intended to support RNAV5. The latter is not yet in place, the UK has plenty of DMEs but they are concentrated in the South and not spread evenly across the country, but will support RNAV1. The limitation for most users is going to be suitable equipment in the aircraft. Multi constellation is likely to be much cheaper and more widely available, even my mobile phone can do that, than boxes which do DME/DME.
For en-route navigation a VOR/DME network makes good sense (although most aeroplanes who need that capability probably carry perfectly adequate INS systems). But, for approaches, you're in a bit of a pot-luck there: if the VOR isn't within say 10 degrees of runway centreline and 10 miles, it's not a lot of use.

G
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Old 21st Nov 2020, 22:49
  #64 (permalink)  
 
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I have fond memories of demonstrating an NDB approach / hold into the BBC longwave radio transmitter at Droitwich (I think... ?) for my IMC rating. You could just about get 198 longwave with 200 on the ADF I remember the controllers at Birmingham getting itchy as we hurtled around and around on the edge of their playground.

A summer or two before, I did a bit of work experience in light aircraft maintenance at Liverpool and one of the mechanics lamented the retirement of a colleague who could get the BBC on the aircraft radio while they worked on the ship. When that colleague left the knowledge left with him. I remember trying to work out how it was done. I was flummoxed until I did that IMC test... great stuff.

Hard to believe that was a decade ago, wow.
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Old 21st Nov 2020, 23:11
  #65 (permalink)  
 
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If you go back a couple more decades or so, to when I started teaching the IMC rating it was even easier, as the Droitwich frequency was 200 kHz which made it a really useful training aid for ADF tracking exercises. It was changed in 1988 to the current 198 kHz which made it harder with “modern” ADF receivers, as you could still get them to point at it but couldn’t really make out the speech so well so harder to “ident”....
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Old 22nd Nov 2020, 05:12
  #66 (permalink)  
 
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The last NDB approach I did for real in IMC without some sort of GPS to provide final approach track guidance was in 1994. Using GPS even if it was “unofficially” always resulted in the flight path of the airplane being aligned with the runway, so I basically ignored the ADF needle.

The last use of the ADF went away when the good rock and roll stations went to FM or satellite. The NDB is 90 year old technology and is long overdue for the dustbin of old crappy nav aids like the radio range. Good riddance !
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Old 22nd Nov 2020, 08:20
  #67 (permalink)  

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Well at least it’s a slight improvement on Decca..... Thankfully that’s gone as far as my part of aviation is concerned. Using a system designed for a ship doing ten knots for IMC flight at 140 kts was ridiculous.
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Old 24th Nov 2020, 15:18
  #68 (permalink)  
 
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Originally Posted by tdbristol View Post
....... In both cases I would have had real problems if I had tried to land using the NDB alone. ........
They are dreadful for SA as, in theory, they get you to a point where you expect to see a certain picture when you break out but, instead, it often spits you out (for the reasons you and others note) somewhere else. OK, not far off but, given you should then be able to land off it, sometimes that's far enough to be a pain to complete the line-up on final and a rapid judgement call is needed as whether it can be flown safely or you need to fly a MA. Snap decisions are never helpful at such times!

Re NDBs en-route, a lovely story of a friend who got his first Jet job on the 727 not that long after getting his IR. Trogging North back to the UK past Portugal as PNF, they got an en-route Hold thrown at them based on an NDB. A Training Captain was PF and so suggested that this would be a good chance for his P2 to demonstrate an NDB Hold. Friend staggered and lurched a few times round the Hold dragging his 100 or so pax along in loose formation behind him before, thankfully, onward Clearance came through and, with much relief he re-established, arrow-like, outbound en route.

With a feel of impending, career-limiting, doom, he handed back to the TC while rapidly considering (a) how up to date his CV was and, (b), if he knew of any leads going in other airlines (any would do!) as he felt sure he was about to be hung out to dry by the TC. The TC turned to him after a short, but ominous, pause and said "Mmmmm, not bad, not bad ....... all I can say is ................ thank God you flew that - I wouldn't have known where to start! I just thought you, having just done your IR, would be best placed to fly that! Very well done!!!!!".

Sums NDB's up really!!!!

Last edited by Hot 'n' High; 24th Nov 2020 at 16:20.
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Old 25th Nov 2020, 12:17
  #69 (permalink)  
 
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With a feel of impending, career-limiting, doom, he handed back to the TC while rapidly considering (a) how up to date his CV was and, (b), if he knew of any leads going in other airlines (any would do!) as he felt sure he was about to be hung out to dry by the TC. The TC turned to him after a short, but ominous, pause and said "Mmmmm, not bad, not bad ....... all I can say is ................ thank God you flew that - I wouldn't have known where to start! I just thought you, having just done your IR, would be best placed to fly that! Very well done!!!!!".


Reminds me of taking my instructor initial skill test out of a somewhat unfamiliar airfield. Five minutes after take-off I realised that I had lost positional awareness. So I turned to my examiner, who was pretending to be my student at that point "So Bloggs, can you tell me where we are right now?", he went into a textbook description of nearby roads and towns and told me exactly where I was, "Well done Bloggs, now onto the first exercise"....

G
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Old 26th Nov 2020, 10:34
  #70 (permalink)  
 
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Originally Posted by Genghis the Engineer View Post
Reminds me of taking my instructor initial skill test out of a somewhat unfamiliar airfield. Five minutes after take-off I realised that I had lost positional awareness. So I turned to my examiner, who was pretending to be my student at that point "So Bloggs, can you tell me where we are right now?", he went into a textbook description of nearby roads and towns and told me exactly where I was, "Well done Bloggs, now onto the first exercise"....

G
That, G t E, as a fellow Instructor (now lapsed) is quick-witted style!!! Absolutely love it!!!!

My CPL GFT also took place from an "unfamiliar airfield". I rang the Examiner, as briefed if he had been delayed and not got in by a certain time, to get the route from him. But that revealed a small snagette.

I was booked into the Flypro to fly the GFT from airfield "A". The route he gave me started at airfield "B" some 70+ miles away and which I'd never even been near let alone to. But that was where he was waiting for me to pitch up, complete with an A/C, to do my Planning followed by the Flight!

The reason I'd never been there is mainly as it was behind a wall of impenetrable CAS ...... policed by fire-breathing ATCOs with an endless supply of MOR forms ..... and which was renowned as "Infringement City" - so the very careful dog-leg required added maybe 20+ miles to the above! No pressure there then!!!

The Ops guys at "A" did a great job springing my A/C early so I could fly at Vne (+ some!) to where my Examiner was waiting. Fortunately, I arrived in time to do my second Route Plan of the day and it all worked out OK .... the ATCO-dragons had continued to sleep soundly as I whizzed past their lair! But I was rather relieved the Examiner didn't ask for the paperwork to do with the first flight tho!

Happy daze!!!! H 'n' H

Last edited by Hot 'n' High; 26th Nov 2020 at 10:36. Reason: Do I get a prize for thread-creep? ;-)
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Old 26th Nov 2020, 11:07
  #71 (permalink)  
 
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Originally Posted by Big Pistons Forever View Post
The NDB is 90 year old technology and is long overdue for the dustbin of old crappy nav aids like the radio range. Good riddance !
The ILS is close to being 90 years old technology as well, and so is the internal cumbustion engine, and fire is even older?

But yes, there are better alternatives now.... until the Kessler Syndrome hits us at least...
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Old 26th Nov 2020, 15:02
  #72 (permalink)  
 
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Originally Posted by jmmoric View Post
The ILS is close to being 90 years old technology as well, and so is the internal cumbustion engine, and fire is even older?.........
But the difference is, in the cases cited above, they all worked as advertised rather than being at the whim of the weather and other gods!!!! Flying NDB approaches in good vis on checks was both amusing .... and sobering! Using GPS as a backup to the NDB worked quite well tho!!!

Seriously tho, you are correct re ILS. What intrigues me is was MLS used much/at all? Seems they had MLS at LHR up until 2017. The Mil have used MLS quite a bit but not sure what civvie uptake there was. I never came across it outside the Mil. I guess, if only a few airlines equiped their aircraft with it (I think BA equiped some of their SH Fleets with it), then the benefits of MLS would have been negated as, particularly at busy fields with a queue down the ILS, you'd have a mix of MLS and ILS traffic so would have to go for the lowest common denominator (ILS) to make sequencing easier. I guess it would be harder to utilise the benefits promised by the MLS on mixed ILS/MLS arrivals - if that were even possible. Dunno!
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Old 26th Nov 2020, 20:01
  #73 (permalink)  
 
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We had MLS on the BA Airbus fleet and it was a total waste of money. It worked perfectly but, as you said, we were never able to take advantage of the benefits of reduced spacing because we were never allocated a discrete runway and therefore had to share with ILS traffic.
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Old 26th Nov 2020, 21:09
  #74 (permalink)  
 
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Originally Posted by eckhard View Post
We had MLS on the BA Airbus fleet and it was a total waste of money. It worked perfectly but, as you said, we were never able to take advantage of the benefits of reduced spacing because we were never allocated a discrete runway and therefore had to share with ILS traffic.
Cheers eckhard, suspected that was the case. I think GPS reared it's head just as MLS was starting to gain traction. Anyway, thanks for the confirmation. Cheers, H 'n' H
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