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NDB approaches???

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Active member
Mar 11, 2002
I have not started my instrument training yet but it seems that a lot of people hate, or have trouble with NDB approaches. Why is this? What makes them so difficult?..............and if you are really motivated, maybe you could tell me how to perform one???
NDB approaches are not hard at all if you understand them. Just remember the needle always points to the station. Instead of trying to figure out MH, MB, and RB, just superimpose the needle on your HI and take the heading off that.
I think the reason most people hate them is because you have to think a lot more. Also, you don't have the same assurances that you are on the correct course like you do with an ILS and we rarely ever do an NDB approach. You'll also start to see many of the uncontrolled fields at smaller airports replace thier NDB's with GPS approaches simply because of the economics. There is very little cost in maintaining a GPS approach versus maintaining and NDB.

I'm not going to tell you everything you need to know about doing an approach, but here are some of my hints.

When tracking an NDB that is either a fixed card or movable card (not slaved) its easier to use your minds eye to super impose the NDB needle on the HSI then it is to do the math. Where ever the needle is pointing is your inbound bearing, and where the tail is pointing is your outbound bearing.

If the NDB is off of the field (i.e. LOM) when you hit the LOM/NDB, just fly the inbound heading. If you do that, you'll probably be pretty close. When you consider the reliability of any individual NDB you'll see that this method is almost as good as trying to track an NDB needle (many of which jump irratically). Also, estimate your winddrift prior to crossing the NDB, this will keep you from having to bracket inside the FAF. None of this should be substituted totally for actually tracking the proper course, but it does help you stay near the course so you don't have to make big corrections.

If the NDB is on the field your job just got a whole lot easier, as long as keep the need straight ahead, your probably going to end up close to the runway. Again, not to be substituted for a good track, but you can eliminate large corrections. Do remember if you have a stiff crosswind you'll come into the NDB straight into the wind.

The above is by no means a complete guide to NDB's, I was just trying to illustrate how you can take some of the thinking out of the approach. The biggest key is to pretend the NDB needle is on your HSI, that will take so much work out of the approach.

I forgot to ad that you should be very sure your HSI is very accurately set prior to beginning an approach. That can be a very big problem if you have flown a couple of hours and then begin the approach with out resetting it.
NDB work

It helps greatly to start by orienting yourself to the station. Tune and ident the station and leave the volume up to monitor the Morse code ident. Parallel yourself with the desired MB. The needle on the ADF always points to the station. If the needle is pointing forward and directly to the station, you are on the bearing. If the needle is pointing to the station but to either side, the station is in front of you and you are either left or right of course. You can intercept the MB inbound by taking a good intercept angle, something like thirty degrees. As an example, let's say you determined that the station is to your left and ahead of you. Turn left on your 30-degree intercept. Hold your intercept angle well and watch the head of the ADF needle. Watch it open up on the right side of the scale. Once the head of the needle opens on the right side of its scale by a number of degrees equal to your intercept angle, in our case, thirty degrees, you've intercepted the bearing inbound. Turn to the course. The head of the ADF needle should be pointing to zero on the card (fixed card).

Outbound tracking is similar. Determine your position relative to the station. Once again, you can always count on the ADF needle pointing to the station. The needle will point to the aft of the scale, which means the station is behind you. Take a good intercept angle and watch the tail of the ADF needle's progress on the upper left or right quadrant of the ADF card, as the case may be. At the point the tail of the needle closes to the number of degrees equal to your intercept angle, you've intercepted the course. Turn to the course. The tail of the ADF needle should be pointing to zero on the ADF card (fixed card) and the head of the needle should be pointing at 180.

At that point, hold heading and watch the ADF needle for drift. If the head or tail as the case may be drifts off zero, you have a crosswind. Take intercept angles again to get back on course but roll out on a heading that keeps the needle from drifting. Probably you'll have to bracket your wind correction angle a couple of times to hold your course.

Common errors include overshooting or undershooting the bearing, and not turning and identifying the station.

Do follow the excellent suggestions above about mentally superimposing the ADF needle on your HI. Of course, if you have an airplane with RMI, you're set.

It is absolutely vital to TUNE and IDENTIFY the station with the Morse code. Leave the volume of the ADF up. If you don't hear the Morse code ident, you cannot rely on the station for navigation.

Good luck with your instrument training.
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As the previous poster mentioned it is paramount that you tune ident. and MONITOR the station. There is no TO/FROM OFF flags. So if you don't have a morse in the background how do you know your following a station. Some ADFs do 360s when looking for stations but its been my experience that some just stay put when they are not working or receiving, WHICH IS NOT GOOD!!!!
I would never base a decision to go ifr to a field that only has a NDB and if I did I'd make sure a airport was close by with a ILS or VOR. I would probably not have a alterate with a NDB only approach unless that airport was VFR. Just personal opinons on the last half.
One more thing...Even if your plane does'nt have a ADF it is a good idea to receive training with them. It is my understanding that the FAA is removing from service when they break instead of fixing them. However, there is actually a airway using ADFs in florida which goes from the southend to Marathon. Also the Bahamas has a few ADF airways and they can be common in Central America. Tegucegalpa (sp?) in Honduras has a approach that uses them. Only problem is it requires dual NDB radios and it requires something like 1300 per nm descent rate if you don't spot the runway till the MAP. LOL Just a little tidbit.
Remember this little phrase and it will make life easier for you. "Push the head" "Pull the Tail". For example; If you're tracking a course to the station of say 360 degrees and the head of the needle is pointing 355. You must "push" the needle back to 360 by pointing your nose somewhere left of 355..(how far depends on winds and airspeed) If on the other hand you are tracking the 180 bearing outbound the opposite is true.. For example; The tail of the needle is pointing to 175, you want to "pull" the tail around to 180. To do this you would steer to somewhere opposite of 180, say 185 to pull the needle back to the desired bearing. (Once again the amount depends on airspeed and windspeed/direction). Remember as a rule of thumb, if it took 10 degrees to get you back on course/bearing, reduce that number by half to start bracketing a good tracking heading.
I just got my instrument in Oct of 2001.

If I could have done the rating without NDB approaches I would have saved a month and tons of money. The approaches were painful to begin because you have to do a little more thinking. However, with a little practice with MS FltSim, and advice from a couple of airline pilots, I mastered the approach. I was feeling great until the next stage of my rating which involved doing all the approaches PARTIAL PANEL.

After a week of blood, sweat and tears of trying to perform the NDB approach partial panel, I found out from the examiner that a partial panel NDB will not be on the exam, maybe just a regular NDB approach.

I learned the TDI/DHI method. Tail Desired Intercept and Desired Head Intercept. PM me or email me when you get to NDB approaches. I am too tired to explain TDI/DHI right now. =) They teach this method at Embry Riddle too I believe so if you can find an ERAU grad, ask'em.

Two pieces of advice:

1) Use a flight sim program at home to do them over and over and over. PAUSE the game and think. You'll get faster each time.
2) Don't be afraid to ask for 'delay vectors' to get absolutely 100% ready to do the approach. The most demanding NDB approach I ever did was into Long Beach. The reason was because of time and I'd mess it up each time b/c I was way behind the aircraft. I would take off from John Wayne Airport (SNA) and get the NDB approach into LGB. The entire flight wasn't more than 10 minutes so basically I took off, switched radios to departures, asked to go off frequency to get the LGB ATIS, came back, immediately got my turn to intercept, which came in after just a minute or so, etc. My chief pilot said, 'ask for delay vectors' and I did and she was 100% correct. It fixed my approaches because I could concentrate on the approach w/o having to brief the approach, do BCGUMPLES.

Anyhow, I think you'll enjoy your IFR rating after you've finished. Lastly, don't quit no matter what. There is a ton of knowledge involved, learn it well so you don't get yourself killed.

If you are going to fly inst you need a good PC based Sim, there are many good ones out there, get one if you don't have one. Then just keep shooting NDB approaches until you master them.
Also remember with a Fed riding with you keep the station ID in your audio, thats the way you make sure the station is working.
The PC-based IFR trainers/simulators is a WHOOOOOLE 'nother matter. There are many pros and cons to using them.

Pros - You can practice your %^!@ off with no plane/instructor expense, and shoot 4 approaches in an hour

Cons - The simulator does NOT replace the instructor, doesn't provide much feedback, and teaches you ONE way to do a maneuver not necessarily the way your instructor or examiner might want to do it.

Nonetheless, I think they can be a valuable supplement to your training. PM me and I can see lots of info on the different programs that are out there.

Then again, there's time in Frasca-type simulators too, which cost money, but is done under an instructors' supervision.

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