I believe that the phrase is Caveat Emptor.
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andrewc
Let me guess, you've been flying training aircraft :O pilot h The uk dealer has always known this, as has everybody else including all the pilots. The CAA just didn't bother, but now they are having a blitz on all things N-reg. |
now they are having a blitz |
They do if they fly to Europe, yes. Do they actually use it? Of course not They fly waypoints in the FMS and AFAIK the FMS doesn't use NDBs for corecting the gyros. But an ADF has to be carried. However, exemptions do exist, for example US Airways A330s which don't carry ADF but have permission to make non precision RNAV approaches in to Gatwick based on the NDB procedure. Presumably there are others too. |
PR wrote:
However, exemptions do exist, for example US Airways A330s which don't carry ADF but have permission to make non precision RNAV approaches in to Gatwick based on the NDB procedure. Presumably there are others too. WF. |
Coincidentally, was talking to a RyanAir pilot about this recently. (He was telling me that although RyanAir have their faults as employers, one big advantage is that they get to go to all kinds of out-of-the-way airports where they get to do non-precision or visual approaches without having ATC virtually fly the aircraft for them..... which is how we got onto the subject). He tells me that, when flying an NDB approach, he will fly the FMS track, and this is what the autopilot will be coupled to, but he will certainly have the ADF tuned too, and will cross-check to make sure it's pointing the right way.
FFF -------------- |
Hmmm,
Just to clarify a little: In an aircraft with a good 'map' display (ie, an FMS-equipped aircraft), it is still the case that for an NDB approach, the primary tracking aid is the ADF. If you go 'out of limits' on the ADF indications below MSA, you must go around. Yes, usually the best way to achieve a good track is by using the map and the tracking information on it, but the means by which you are navigating must be the ADF indications. And yes, in the past year, I have done NDB approaches in 737s. It's worth mentioning that the GPS inputs on the 737-NG fail reasonably often (for a typical line pilot, twice a year would not be unusual), and I have had a number of problems with map shift, and once lost the map altogether during a non-precision aproach, because of a technical failure. If you don't think map shift or the FMC is a problem, do some research on the A320 Addis Ababa incident a short while ago... Regarding light aircraft, if the GPS in a Boeing, or its map, can let you down, then do you really want to place all your faith in a couple of thousand pounds' worth of panel-mount kit? |
Kit
Map shift is not really going to be an issue on a typical GA IFR GPS installation. GA GPS systems do not attempt to blend GPS data with other data (such as VOR/DME) to establish position, therefore there will be no sudden shift in position. If GPS integrity is lost, the display will be flagged (or 3D nav will degrade to 2D) and/or a RAIM warning will show for the approach. What did you have in mind, in the GA context? 2D |
Simply, a GPS approach, during which things get a little out of kilter, followed by the system's recognition of this, and loss of GPS navigation information...
Leaving you part-way down an approach, with no accurate navigation information... All the RAIM messages in the world won't help you find your way out of trouble, when you have no tracking aids available, nor the current ability to interpret them... My post was perhaps by way of an attempt to counter IO540's remarks, which seemed to perpetuate the current myth that transport aircraft navigate almost exclusively by computer - jurassic navigation aids such as ADF/NDB still have a part to play, albeit very seldom. I might add, that if technology provided all the answers, we would be flying a lot more MLS approaches than we are! (edited to add a new thought - there's honesty!!!) |
Leaving you parrt-way down an approach, with no accurate navigation information... All the RAIM messages in the world won't help you find your way out of trouble, when you have no tracking aids available, nor the current ability to interpret them... If you lose RAIM during a GPS approach (or GPS guidance), then you fly the missed. If you lack the guidance for the missed, you climb back above MSA and revert another aid. It would be possible to sound unduly alarmist about GPS approaches. They work remarkably well. 2D |
At the risk of being even more boring, for which I apologise in advance...
I didn't say it was map shift. Map shift and GPS failure or degradation are two different things - both with potential to do harm to the navigator (air, land, or sea). My first post here clearly differentiated between map shift and GPS problems. 'You fly the missed'... Tracking, just, what, to your next destination? GPS approaches may work remarkably well, when the GPS works remarkably well (not all the time in my very limited experience). So do NDB approaches, VOR approaches, and ILS approaches, not to mention SRA and PAR, TACAN, and QGH (what fun!). By the way, 'losing RAIM' and having a GPS failure are not the same thing... |
Troll alert?
I can only repeat the extended rumour that I have heard. I just noticed that "the lancastrian" registered with pprune just before he posted the original "rumour". He posted a similar thing on my web site, and then failed to make direct contact with me when requested. After giving him some fair time, I deleted the thread. He then posted it on pprune. I wonder if his middle name is "troll" Hummn. Ian |
Kit
I would put my trust in GPS any day over ADF. In the event of a failure of the approach aid, whether it's GPS or an NDB, the procedure is the same and often you have the same degree of guidance available... GPS doesn't add a new dimension to the problem. Plenty of places now have standalone GPS approaches operating, and I've flown many of them in the last year. So far so good. I'm not clear what point you are attempting to make about GPS. Are you suggesting as seems to be the case in your first posting, that they are not adequate to be a primary source of approach guidance? If so, are you going to tell the FAA and the many other authorities who think otherwise, or should I? When we talk about overlay approaches, I know that the correct response is to tune and trust the underlying approach aid, but given a choice between an unflagged GPS and an NDB on a stormy night at a coastal airfield, I wish you all the luck in the world with your ADF. 2D |
2D,
Lots of private pilots, in my experience, rely almost absolutely on GPS to navigate en-route, and many rely upon it for approaches. My points are: First, IO540's comments were a little misleading, regarding use of ADF on large aircraft. Second, many people seem to think that GPS, with or without RAIM, is almost infallible. That's certainly not the case, and we should be aware of that fact. If we are moving towards a world in which there is only one navigation aid, GPS, (and it's an apparently attractive world, too, from many points of view), then we need to understand that we are placing all our eggs in one extremely fragile basket. Using the same aid for en-route and approach guidance is nothing new, but to only have one aid available (or indeed, to become complacent and lose skills appropriate to interpreting the other ones) is altering the risk mix significantly. Noting your location, perhaps we could chat this over in Mitchell one lunchtime this week, if you wish? |
Happy to chat it over, in Mitchell or otherwise. However, my concerns were:
a) By introducing the concept of Map Shift in your first posting, you were introducing a problem specific to FMS systems which does not have a parallel in GA GPS systems, and which does not have any bearing on the use of GPS in light aircraft for approach purposes. If the GPS is showing a RAIM warning, an Integrity warning, or is navigating in 2D mode only, then you don't use it for approaches. Furthermore, you drew an unfavourable comparison between IFR approved GA GPS systems and airliner FMS equipment Regarding light aircraft, if the GPS in a Boeing, or its map, can let you down, then do you really want to place all your faith in a couple of thousand pounds' worth of panel-mount kit? b) Your comments relating to GPS failure and the difficulties of executing an approach 'Leaving you part-way down an approach, with no accurate navigation information... All the RAIM messages in the world won't help you find your way out of trouble, when you have no tracking aids available, nor the current ability to interpret them... You fly the missed'... Tracking, just, what, to your next destination? I hope this sets out the questions that I think arise out of your posting. FWIW, I think IO540 was nearer the mark than you give him credit for. 2D |
Does anyone have some more info on this ADF/DME retrofit for Cirrus aircraft?
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Does anyone have some more info on this ADF/DME retrofit for Cirrus aircraft? |
does anyone have any pics?
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Here's one from the COPA Forum, where you're likely to get much better answers to this kind of question:
http://www.cirruspilots.org/uploaded...ADFpicture.JPG |
I think everyone is missing the most important point.
ADF is an absolutely critical component of many flights, particularly those during which the Man Utd game is being broadcast live on BBC 5-Live .... alledgedly .... ;) FF:ok: |
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