ADF outbound - needle always swings towards the tail?
A lot of theory hocus pocus surrounds use of the ADF. Probably the worst advice, when you only have one ADF and are flying point to point over some distance, is to switch from NDB station behind to station ahead at about the half way mark. Switch over as soon as you have a decent signal from the station ahead.
I have seen pilots have a brain fart and track away using the wrong numbers, e.g. 137 instead of 173. But once you have a lock on to the station ahead, needle on the nose will get you there every time. Sure, when doing a test you need to make some effort to lay off drift en route and definitely need to maintain published tracks on an NDB approach.
If drift is constant your application of Pythagoras is correct - the needle definitely does not get closer to the tail as you move away from the station. If you are doing an NDB approach your instructor may not be allowing for the fact that usually drift decreases as you get closer to the ground, for obvious reasons.
Better simulators actually have wind gradients built in to their programs, or the instructor can dial in winds at various levels to reinforce the need to reduce or change drift correction on final approach.
I have seen pilots have a brain fart and track away using the wrong numbers, e.g. 137 instead of 173. But once you have a lock on to the station ahead, needle on the nose will get you there every time. Sure, when doing a test you need to make some effort to lay off drift en route and definitely need to maintain published tracks on an NDB approach.
If drift is constant your application of Pythagoras is correct - the needle definitely does not get closer to the tail as you move away from the station. If you are doing an NDB approach your instructor may not be allowing for the fact that usually drift decreases as you get closer to the ground, for obvious reasons.
Better simulators actually have wind gradients built in to their programs, or the instructor can dial in winds at various levels to reinforce the need to reduce or change drift correction on final approach.
Last edited by Mach E Avelli; 12th Mar 2014 at 22:54.
'Mach' that is definitely not good advice there you saying keep the needle on the nose & you will get there every time then saying during a test you need to lay off drift etc. What's a test got to do with it? I only hope anyone reading that doesn't take that on-board. Doing as you suggest is bloody dangerous, such poor airmanship thinking can take you lower than yr original track LSALT calcs & send you into high terrain.
In yr own words "probably the worst advice"
Wmk2
In yr own words "probably the worst advice"
Wmk2
Probably the worst advice, when you only have one ADF and are flying point to point over some distance, is to switch from NDB station behind to station ahead at about the half way mark. Switch over as soon as you have a decent signal from the station ahead.
Dr
Somehow I knew that my heresy would incur criticism. But, let's put use of the ADF en route in perspective. If your aircraft even has one these days, that is. Good airmanship suggests tuning en route NDBs to verify correct GPS or FMS inputs, but actually using it en route in today's strict environment of required navigation accuracy is more likely to be on an IR test only - hence that comment.
Or when Mr Garmin does a dummy spit, as happened to me only this week when ferrying the bugsmasher to its new home in Tassie. (Sadly, said bugsmasher has no navaids other than a compass, but it was good enough, even with 25 degrees of drift).
As for keeping the needle on the nose being "bloody dangerous", consider the buffers that are imposed on NDBs when calculating en route LSALT. It would take a helluva crosswind component combined with serious disregard of heading and altitude to put one in danger. However, to satisfy the pedant among us I will modify my advice to: tune the station ahead as soon as able and follow the needle on the nose until you are CLOSE enough to be satisfied that the bearing is good enough to apply drift correction as necessary.
By following my own "bloody dangerous" advice I prevented one ferry pilot from taking us nearly 40 degrees in the wrong direction one dark night over the Pacific and on another occasion stopped my F/O from straying us into Russian airspace in the days when one got shot down for such mistakes. And guilty as charged, I once backtracked the distance number on the chart, because it was similar to the bearing number, in terms of the quadrant I expected (the old 153 versus 135 blunder). Only realised my cock-up when I put the needle on the nose to listen to some distant music on AM and looked at the RMI angle.
And before you shout/shoot me down for that, a powerful AM broadcast station on the nose is a better en route aid than an NDB too far behind the aircraft. Legal or otherwise.....
Or when Mr Garmin does a dummy spit, as happened to me only this week when ferrying the bugsmasher to its new home in Tassie. (Sadly, said bugsmasher has no navaids other than a compass, but it was good enough, even with 25 degrees of drift).
As for keeping the needle on the nose being "bloody dangerous", consider the buffers that are imposed on NDBs when calculating en route LSALT. It would take a helluva crosswind component combined with serious disregard of heading and altitude to put one in danger. However, to satisfy the pedant among us I will modify my advice to: tune the station ahead as soon as able and follow the needle on the nose until you are CLOSE enough to be satisfied that the bearing is good enough to apply drift correction as necessary.
By following my own "bloody dangerous" advice I prevented one ferry pilot from taking us nearly 40 degrees in the wrong direction one dark night over the Pacific and on another occasion stopped my F/O from straying us into Russian airspace in the days when one got shot down for such mistakes. And guilty as charged, I once backtracked the distance number on the chart, because it was similar to the bearing number, in terms of the quadrant I expected (the old 153 versus 135 blunder). Only realised my cock-up when I put the needle on the nose to listen to some distant music on AM and looked at the RMI angle.
And before you shout/shoot me down for that, a powerful AM broadcast station on the nose is a better en route aid than an NDB too far behind the aircraft. Legal or otherwise.....
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a powerful AM broadcast station on the nose is a better en route aid than an NDB too far behind the aircraft. Legal or otherwise
Trouble was, one used to sing along to some of the songs!
Low powered NDBs can be next to useless if thunderstorms are about, or at night. But a high powered beacon will be generally quite useable, albeit with some fluctuations of the ADF needle, even during quite severe activity. As long as pilots apply CDF with regards to not getting too close to the thunderstorm itself and using sensible headings during the actual approach, NDBs are still a reliable navaid. More's the pity they are being withdrawn. If star wars ever breaks out and the GNSS gets scrambled we will miss the good old NDB.
A lack of simplicity in what were taught, and how we see it is exactly why everyone screws up the NDB in flight and in tests.
Many instructors don't know, so I can't imagine how the students are supposed to.
Couldn't agree more. The simplest, most easy to understand technique when flying an NDB approach with an RMI is this:
You are the tail of the needle, correct left or right to the required outbound bearing tracking to and from the station.
That's it.
Many instructors don't know, so I can't imagine how the students are supposed to.
Couldn't agree more. The simplest, most easy to understand technique when flying an NDB approach with an RMI is this:
You are the tail of the needle, correct left or right to the required outbound bearing tracking to and from the station.
That's it.
Last edited by stilton; 11th Apr 2014 at 06:45.
