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ADF and its Usage?

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Hello all,I have recently started using the PMDG and have a good idea about the aircraft from previous use of the B734-B735. My question is about the Automatic Direction Finder (ADF). What is it? How do you use it? Where can this be found on lets say the airport charts? Any help would be appreciated.Waqas

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Hello all,I have recently started using the PMDG and have a good idea about the aircraft from previous use of the B734-B735. My question is about the Automatic Direction Finder (ADF). What is it? How do you use it? Where can this be found on lets say the airport charts? Any help would be appreciated.Waqas
2 seconds of searching on google gave me this.... http://www.navfltsm.addr.com/ndb-nav-adf-1.htmhttp://www.avionix.com/store/adf.htmlRob

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I'm pretty sure you will basically never fly an NDB approach in a 737 anywhere in the developed world... they're still in use in some non-radar environments in parts of South America, Africa etc though. I'd personally be very scared to try one in real life in a high performance jet haha.The basic idea though is that the ADF needle always points to the NDB station. You can use this to fly bearings (they're not called radials with an NDB) to and from the station. The problem is that an ADF doesn't give you concrete intuitive information about your position relative to that bearing like a VOR/ILS gauge's CDI does. This can lead to big problems in a cross wind if you just keep the ADF needle pointing at the station because you'll effectively "home" in on the station in a spiral pattern (if the ground track was viewed from above) potentially bringing you into conflict with terrain, traffic etc... Planes like the 737 make it much easier to do though because of the RMI gauge, which always correlates aircraft heading with the bearing pointer. In a Cessna or something that doesn't have a movable card ADF or slaved RMI, you have to do math in your head to figure out what headings you need to fly to get on the bearing you want.It's fun to try it though in FS with IMC and see how close you are when you do break out of the soup... Just get some charts off Flightaware or something and pick one to try. Start off small using one of the FS default planes before trying to do it in a jet.

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I'm pretty sure you will basically never fly an NDB approach in a 737 anywhere in the developed world... they're still in use in some non-radar environments in parts of South America, Africa etc though. I'd personally be very scared to try one in real life in a high performance jet haha.The basic idea though is that the ADF needle always points to the NDB station. You can use this to fly bearings (they're not called radials with an NDB) to and from the station. The problem is that an ADF doesn't give you concrete intuitive information about your position relative to that bearing like a VOR/ILS gauge's CDI does. This can lead to big problems in a cross wind if you just keep the ADF needle pointing at the station because you'll effectively "home" in on the station in a spiral pattern (if the ground track was viewed from above) potentially bringing you into conflict with terrain, traffic etc... Planes like the 737 make it much easier to do though because of the RMI gauge, which always correlates aircraft heading with the bearing pointer. In a Cessna or something that doesn't have a movable card ADF or slaved RMI, you have to do math in your head to figure out what headings you need to fly to get on the bearing you want.It's fun to try it though in FS with IMC and see how close you are when you do break out of the soup... Just get some charts off Flightaware or something and pick one to try. Start off small using one of the FS default planes before trying to do it in a jet.
Hey Thanks alot for the help everyone. I checked out both sites in tried a flight myself and i will need some practice but i think i will get the hang it. I agree that it is probably not needed it on many flights but its a good tool to have for malfunctioning GPS or so on.Thanks again

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Hey Thanks alot for the help everyone. I checked out both sites in tried a flight myself and i will need some practice but i think i will get the hang it. I agree that it is probably not needed it on many flights but its a good tool to have for malfunctioning GPS or so on.
In case of malfunctioning GPS (very rare event) you would rather use VOR/DME approach, not NDB. Like Ryan said - use of NDB is pretty much limited these days to 3-world countries. Some aircraft with the latest avionics are even no longer equipped with the ADF.

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There's nothing scary or mysterious about using the NDB in a hi-performance jet transport. They are still used extensively in Europe on STAR's and SID's as well as a few enroute airway fixes. Many are still used for holding fixes in Europe as well.It's not a difficult system to comprehend or understand and works just fine in transport aircraft. Instead of homing to the station, you set up bracketing just like a VOR and fly it the same way. You have to pay more attention to the information and correct accordingly.I doubt many in Europe would consider their homeland a Third World country.Michael C.

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ADF/NDB equipment was a nice feature when it was co located with the airfield or as a LOM (locator outer marker) as it helps (slightly) with orientation to the airfield or your closure to the ILS in the case of analouge flight deck aircraft.As an en route navigation tool it was only slightly better than dead reckoning. It is prone to many errors, coastal, mountain etc and if you ever used one near a storm the needle would point to the nearest lightning flash!As mentioned they are still in use in certain parts of the world as they are cheaper than VOR equipment, most LOMs have now been closed down in the UK due to the cost of keeping them calibrated,GE and GW at LGW were withdrawn last year and MCH at manchester has now been turned off.I remember flying in the outback of Australia years ago where they published the location of commercial radio stations as its possible to tune the ADF to their frequency and the needle will point to the transmitter and use it to navigate as a last resort, and listen to the news and music at the same time!Thankfully IRS/GPS RNAV has replaced the NDB and to a lesser extent VOR navigation on modern aircraft.Pilots are still tested on the so called "non precision" aproaches (NDB,VOR) but these are usually just flown in LNAV and VNAV with the autopilot and so all you are really doing is following a FMC coded procedure with the raw data needles monitored to make sure they are in +- 5 degrees of the QDM.CheersJon b

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you set up bracketing just like a VOR and fly it the same way.
You definitely don't fly it it the same way as VOR. There is huge difference between tracking a VOR radial and trying to follow a ground track using ADF. Any IFR-rated pilot would testify to it. These two devices have little in common from the pilot's point of view. It is a lot harder to do it with ADF when x-wind is involved hence a relative lack of enthusiasm among pilots for using NDB as type of approach when other approaches are readily available (and in affluent countries they usually are).

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I am an IFR rated pilot and you set up a WCA and bracket it just as you would a VOR.If the needle starts moving you don't have enough WCA in, so bracket more for another five minutes. If it doesn't move, then fly back to the original course plus the correction. If it moves, bracket more. You set up the tracking the same way for either nav-aid.It's not rocket science.

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You definitely don't fly it it the same way as VOR. There is huge difference between tracking a VOR radial and trying to follow a ground track using ADF. Any IFR-rated pilot would testify to it. These two devices have little in common from the pilot's point of view. It is a lot harder to do it with ADF when x-wind is involved hence a relative lack of enthusiasm among pilots for using NDB as type of approach when other approaches are readily available (and in affluent countries they usually are).
Michal, are you a rated pilot of any description???

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Michal, are you a rated pilot of any description???
You bet. And sorry but ADF is much harder to interpret and fly. I guess most pilots must feel this way because NDB approaches are out of favor. Folks avoid them during IFR check rides like plague, if they can only satisfy "two non-precision approaches" requirements some other way - they do it.

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You bet. And sorry but ADF is much harder to interpret and fly. I guess most pilots must feel this way because NDB approaches are out of favor. Folks avoid them during IFR check rides like plague, if they can only satisfy "two non-precision approaches" requirements some other way - they do it.
"Folks" don't have the option of avoiding an NDB procedure during the check ride. They fly the procedure the examiner dictates during the practical exam.

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"Folks" don't have the option of avoiding an NDB procedure during the check ride. They fly the procedure the examiner dictates during the practical exam.
Again, not true at all, at least not in my neighborhood. Show up with a "non-ADF" aircraft for the check ride and you don't have to fly one as long as you can fly two other non-precision approaches. I have not heard of an examiner (in the San Francisco Bay Area where I live) to insist on NDB approach these days and if you find one you go to someone else. Indeed, folks would typically now fly GPS and VOR in a well equipped aircraft.By the way, if you never heard of it, in the days when NDB approaches were common - it was the number one cause of checkride failure, not rocket science but still cause of some difficulty for many newbie IFR pilots - these are facts.

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Again, not true at all. Show up with a "non-ADF" aircraft for the check ride and you don't have to fly one as long as you can fly two other non-precision approaches. I have not heard of an examiner to insist on NDB approach these days. Indeed, folks would typically fly GPS and VOR these days in a well equipped aircraft.By the way, if you never heard of it, in the days when NDB approaches were common - it was the number one cause of checkride failure.
I'll throw in a few cents on the NDB stuff. As a Canadian, you grew up on these NDB approaches, holds, etc. They aren't rocket science. The needle points to the station. Simple. You add wind correction to keep your required track to the station constant. Again, not reocket science as described. As for a check ride, and speaking as a former check A check pilot, if I told my candidate they have to do and NDB approach they HAVE to do an ndb approach. A good pilot would use all their resources to the advantage and use the GPS to help them out but they still have to use the NDB as a primary source of navigation. The only crummy thing about NDB is they are very susceptible to interference (T-storms, coastal effect, etc.).

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I guess it seems like over in the USA they are virtualy gone, here in Europe they are still very common and as another poster mentioned you still see them along the Localizer.Rob

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Flying an NDB approach in IMC with crosswind and seeing the airport ahead when you drop out of the clouds is one of the most satisfying accomplishments of instrument flight. I love 'em now for the challenge and opportunity to use my airmanship skills but OMG I hated them when I was working on my instrument rating.I still from habit tune in the LOM (ndb collocated with FAF or outer marker) if there is one on ILS approach to add to my situational awareness, and I use the needle swing to start my timer on the final approach. Many of these are being decommissioned in the US but there will still be plenty of locations around the world where the beacon is all you get. By the way, the timer on an ILS approach was taught to me as an important backup to GS. If you loose GS continue the approach to LOC mins and use elasped time for the missed approach (in many cases).

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Showing up in a non-equipped aircraft would certainly eliminate the NDB procedures. The aircraft at our school and others I rented all had NDB. Back then it was the norm. Every aircraft had NDB and it was taken for granted that you would learn to use it and there would be an NDB procedure to accomplish on the ride.I guess it has fallen out of regular use these days in the States.

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I have a random flight generator and the other day I flew an NDB approach in the MD11!!!!! Fortunately the runway had just appeared (fog, not magic) as the NDB passed underneath.

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...and the other great thing about ADF is that you can use the equipment to tune in a 'fun' radio station to listen to, for example BBC World Service (although I suspect that this might not be modelled here!). Definitely whiles away the hours on long trips.James

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I guess most pilots must feel this way because NDB approaches are out of favor. Folks avoid them during IFR check rides like plague, if they can only satisfy "two non-precision approaches" requirements some other way - they do it.
This simply demonstrates a lack of both the knowledge and skill of the pilot.A competent pilot will never have a need to avoid them like the plague...Regards,Jeremy

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Hey Soulman.. You avoid what you can avoid.. But it does not mean that pilot's don't have the knowledge of an NDB approach.You go through all procedures during your instrument training and even practice in the simulators and in the airplane with your instructor before any checkride.The NDB is pretty stressfull because you really need to mentaly stay infront of your airplane all the time, and when you are on a checkride you allready are stressed out.The human mind can only deal with that much stress, and when you upon that have to do an NDB approach with the hood on, you can easily reach your stress limit.What happens then is that the mind confuses every input it gets from your surroundings and you mess up. This example is of course for a pilot that just finished his/her's flight trainingand have a limited time IFR and are sitting there with 35 hours of instrument training and are going for a checkride. As experience comes you tackle your tasks more easily.I have a friend of mine who was a captain on the Dornier 228 in Norway for a number of years (He is now a FO in a 737). They flew to alot of small airstrips in the northern part of Norway, and some of those airport had only NDB approaches.Every now and then he would get a company check pilot on his flights, and he was required to do the NDB approaches with a loaded airplanefull of passengers. He said that you get used to the NDB's like everything else and finally you don't even think about them. You just do them.I think even in his new job flying the 737 they are required to do an NDB approach when ever he is in the Simulator doing checkups.I do not see any problems of performing an NDB approach in the 737 eighter. You have the autopilot to relieve some of the stress involved in NDB approaces.I'm pretty sure most of us realworld pilots on this forum has tried a NDB approach in the PMDG 737 and it worked out just fine?

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I have to agree with soulman here, NDB is just another technique. How much simpler does it get then "The needle points to the beacon". If the pilot really has that much difficulty getting their head around the idea that wind will blow them off course and must be corrected for, (i.e. the difference between heading and track) then you really must ask if they should be flying at all.Such a pilot will not be more comfortable with VOR. Point the plane on the heading of a radial and you are going to be off course pretty soon and that pilot won't know why.Such a pilot will not be able to work out their fuel needs, since they can't allow for head wind and tail wind components on each leg. Such a pilot won't even be able to tell you when they expect to reach their destination? What then? Do they just keep going until they get lucky? Most aircraft do not have a menu option with a moving map updated by magic so its always accurate. The whole point of instrument flying is to put your aircraft exactly where you want it to be, when you want it to be there, wether or not you can see out the windows. The techniques used for NDB approaches form the basis of all other techniques. If you are not comfortable with them, then go and practice until you are comfortable.

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The NDB procedure will be coded in the FMC so,depending on company procedures, can be flown using LNAV and VNAV woth the raw data needles displayed on the ND just to confirm that the pink string is in the right place. In this respect flying the NDB aproach in a modern FMC/EFIS equiped aircraft is exactly the same as flying a VOR or RNAV aproach. The aircraft takes care of the tracking. Lazy? relative to an analouge flight deck yes maybe, but its a hell of a lot safer,especially at the end of a long haul flight.cheers Jon

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Fly your Vor approaches entirely on the RMI without DME (on a non dme required approach ofcourse) and you will find yourself practicing the same skills required for almost all DME approaches. I prefer flying the approaches referencing the RMI anyway. As long as you know your radial and can modify your heading for changing conditions to stay on track, it's easier to build situational awareness for the navigation environment.Jeff Barco

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