GPS vs ADF
Dan Taylor
I am very interested in the ADF vs GPS debate, as my limited
panel space cannot support both. I also cringe when thinking
about the cost of an ADF receiver and the limited performance
it offers.
My instrument training was a rather smooth process, and NDB
approaches came very easily. I would like to credit my
engineering and math background, but then that wouldn't
support why I could not figure out reciprocal headings
and compass only turns to heading. My brain turned to mush
on the simplest of addition/subtraction problems.
On most NDB approaches, in actual conditions we had to revert
to localizer approaches if available. On one approach into
CVO (Corvallis, Oregon) the controller vectored me to the
NDB because I could not receive it until I was 5 miles from
it. Turns out, that the receiver was not aligned properly
but in general, I came away with a lack of respect for this
navaid. And this discussion should include the error introduced
by DG errors in heading, compass and setting errors, and
all the atmospheric and AM contributions.
Now, since GPS positioning give you all the nav information
that the ADF does, with much more ... GS, time to station,
etc. it appears to me that the time has come to put the
old technology to rest. This demands a new approach
methodology, as you no longer have the convenience of an
indicator that points to the radiated source, however
there are some GPS systems that support an 'OBS' function.
The Garmin 150 (and 155, except you need a synchro external
OBS indicator) would allow holding over an NDB, or full
approach as if the NDB was a VOR. I am not sure why all
GPS manufactures do not support this 'OBS' mode, but I
suspect they will in the future.
As mentioned previously, the only advantage an ADF has over
the GPS, is that you can listen to music and the evening news
with it.
comments ?
dan
/\ Daniel Taylor email: d...@sd.com
/\/ \ Beaverton, Oregon
/\/ \ \ commercial,instrument,multi,seaplane
/ \ \ \ piper pa28-235 n8933w
spirit of adventure
David E Allen
: I am very interested in the ADF vs GPS debate, as my limited
Having to choose between the two, GPS is the more accurate and informative
system, of course. GPS is also much more expensive. And not getting cheaper
yet! Just got word from Jepp/Garmin yesterday that they have added special
use airspace to my datacard subscription. Whoopee. This is for an IFR GPS, so
it's of very limited use, but they feel justified in like charging me $50
more per year for it on top of the already outrageous $550/yr. :-( When it
comes to finances, I wish I just had a good ADF. Just ask me why I haven't
flown much since the GPS was installed. :-(
: there are some GPS systems that support an 'OBS' function.
: The Garmin 150 (and 155, except you need a synchro external
: OBS indicator) would allow holding over an NDB, or full
: approach as if the NDB was a VOR. I am not sure why all
: GPS manufactures do not support this 'OBS' mode, but I
: suspect they will in the future.
I think it's mainly needed for approach certification, although note that it
is to be used only for holds and procedure turns; NOT for approaches past
the FAF. (Although if I ever need to make an emergency descent to an airport
without an approach, I will probably "invent" my own approach by engaging the
OBS mode along the direction of a convenient runway.)
dave allen - Fly because you love it.
Ade Barkah
: As mentioned previously, the only advantage an ADF has over
: the GPS, is that you can listen to music and the evening news
: with it.
The `problem' with GPS is that it is a much more complex
system. And as the Law goes, the more complex a system, the
more places something can go wrong. I would hate to be in
IMC with only a GPS when the Department of Defense decides
to turn off GPS for some oddball reason. Or when the GPS
firmware decides to crash because of a software bug. Or
when some Jepp engineer messes up when releasing the
navigation database. There are just too many variables,
which also translate to $$$ for a truly reliable system.
And don't think these software errors don't/will show
up. Safety-conscious software engineering is a relatively
young field (in fact the whole software engineering field
is pretty green), and not widely understood. We have had
some major problems with software in other sensitive areas
such as nuclear reactors and in the medical field.
ADF, on the other hand, is a much simpler unit, and sometimes
it's good to keep things simple (er, the KISS principal.)
I think for this safety/reliability reason alone, GPS shouldn't
be used as the only means of IFR navigation at least for the
next several years; that is, you should always have a backup
system such as VOR and/or ADF.
Regards,
-Ade Barkah
--
Head of Development
Renaissance Knowledge Systems
Englewood, Colorado
Mike Ciholas
mba...@teton.Mines.Colorado.EDU (Ade Barkah) writes:
>Dan Taylor (d...@aviator.tessi.com) wrote:
>: As mentioned previously, the only advantage an ADF has over
>: the GPS, is that you can listen to music and the evening news
>: with it.
>
>The `problem' with GPS is that it is a much more complex
>system. And as the Law goes, the more complex a system, the
>more places something can go wrong. I would hate to be in
>IMC with only a GPS when the Department of Defense decides
>to turn off GPS for some oddball reason.
You should be aware that VORs also share this "feature", that is, the
DoD can turn off the navigation information. To my knowledge, this
feature has never been exercised in recent history.
>ADF, on the other hand, is a much simpler unit, and sometimes
>it's good to keep things simple (er, the KISS principal.)
ADF is simpler electronically, but it is not simpler for the pilot.
KISS the pilot, give them GPS.
>I think for this safety/reliability reason alone, GPS shouldn't
>be used as the only means of IFR navigation at least for the
>next several years; that is, you should always have a backup
>system such as VOR and/or ADF.
I don't think anyone advocates IFR with only one nav means.
Mike Ciholas
mi...@lcs.mit.edu
Roy Smith
> ADF is simpler electronically, but it is not simpler for the pilot.
> KISS the pilot, give them GPS.
I'm not even sure that "simpler electronically" has much meaning.
We have reached the point in electronics where component count is no longer
a valid measure of reliability. Sure, an ADF is a lot simplier than a GPS
as far as component count or circuit complexity goes, but does that really
mean it's less likely to fail?
The computer I'm writing this from (a DECstation 5000/240 running
Ultrix with a few 10's of Mbytes of RAM and a few Gbytes of disk) is a
pretty complex beast, as far as component count goes (but nothing too
exciting by modern standards for a personal workstation :-)). Hard to
imagine anything that "complex" could be very reliable, yet it's been
running with no problems now for almost 4 months:
9:04pm up 111 days, 7:12, 2 users, load average: 0.16, 0.03, 0.00
The last time I rebooted it was because I had to turn it off to move
it when we re-arranged the lab. Lacking another move or a power failure, it
wouldn't be surprising to see it hit 6 months or a year of constant
trouble-free operation. I can think of lots of "simple" things which could
never run that long without a lot of tweaking and adjusting.
No, I don't buy the idea that GPS is more error prone because it's
more "complex". An ADF may be simple from a theoretical standpoint, but if
it breaks, no combination of black plastic tape, spare wire, and a
leatherman tool is likely to fix it in the air. Given that, does it really
matter how many fewer components it has than a GPS, or that it's completely
analog, or that they've been making them for decades?
--
Roy Smith <r...@nyu.edu>
Hippocrates Project, Department of Microbiology, Coles 202
NYU School of Medicine, 550 First Avenue, New York, NY 10016
"This never happened to Bart Simpson."
jpri...@america.com
>
> I am very interested in the ADF vs GPS debate, as my limited
> panel space cannot support both. I also cringe when thinking
> about the cost of an ADF receiver and the limited performance
> it offers.
>
Go with the GPS. This is a no-brainer.
>
>>>>
------------------------------------------------------------------------------------
John A. Pringle jpri...@america.com (904) 365-2303
------------------------------------------------------------------------------------
Bob Noel
> >
> > I am very interested in the ADF vs GPS debate, as my limited
> > panel space cannot support both. I also cringe when thinking
> > about the cost of an ADF receiver and the limited performance
> > it offers.
> >
> Debate? What debate?
>
> Go with the GPS. This is a no-brainer.
Hardly
Maybe you should consider the (current) cost of an IFR-certified
GPS receiver vs the expense of a used ADF then maybe you'll figure
out why there is a debate. Depending on where you fly, an IFR GPS
doesn't always offer an operational advantage. Also, depending
on how often you fly, the payback for the current IFR GPS receivers
might be a bit too long for some.
Bob Noel aka Kobyashi Maru
WARNING: my email name may not work
My views are my own, not MITRE's
(why use a disclaimer when people are
too ---------- to understand it?)
Ade Barkah
still requires backup instruments for GPS. The most dangerous
position you can get into is you get into a false sense of
security because you already think GPS is foolproof.
The FAA does not agree with you, nor should they.
I stand by what I've said before. The more complex a system is,
the more places things could go wrong. It will take longer and
be more expensive to validate, especially because there is so
much to risk.
GPS isn't there yet, and you can't rush it to be ready. Some of
you may not like that, but welcome to reality.
Mike Ciholas
mba...@teton.Mines.Colorado.EDU (Ade Barkah) writes:
>
>Don't jump on the bandwagon so fast. Ask yourselves why the FAA
>still requires backup instruments for GPS.
[I thought this was no longer true. In any case there is a plan to
eliminate this requirement, if it still exists.]
>The most dangerous
>position you can get into is you get into a false sense of
>security because you already think GPS is foolproof.
Is this not true of all technology? If two navigation sources differ
and one is GPS, guess which one I trust. Yup.
>The FAA does not agree with you, nor should they.
The FAA has moved on GPS faster than a cat on a hot tin roof. Read
about the WAAS service that the FAA is planning. This is one of the
most ambitious, foresighted, plans I have ever heard from a federal
agency (its only failing seems to be that it isn't internationally
aware).
>I stand by what I've said before. The more complex a system is,
>the more places things could go wrong. It will take longer and
>be more expensive to validate, especially because there is so
>much to risk.
This argument, that GPS has more "moving parts" and is therefore
unilaterally more prone to failure, is completely bogus. This is like
saying an airplane is more likely to fall apart because it has more
rivets. GPS has more moving parts becuase the parts "move"
independently and it is not required that every part function for the
system to function. A complete analysis of the failure potential is
very involved and I would suggest that you have not done so.
My belief is that the GPS system is the most reliable and accurate
navigational system ever invented. I have come to this belief by
understanding how it works. The addition of the WAAS system will make
it incredibly reliable and accurate over the entire nation.
>GPS isn't there yet, and you can't rush it to be ready. Some of
>you may not like that, but welcome to reality.
Oh, great god of navigational wisdom, the mere people of this planet
have deluded themselves and must be shown the true path to navigation
salvation. Thy must speak forth and strike down the great GPS myth of
operational status, and cursed be the motion of aluminum chariots
guided by this devilish force.
[ :-) for the humor impaired ]
In any case, if you have to choose between and ADF and a GPS, the
choice is stunningly clear. In my case, I have an ADF (a KR87) which
I am keeping because I like it. But I wouldn't keep it over a GPS.
Mike Ciholas
mi...@lcs.mit.edu
David E Allen
: >Don't jump on the bandwagon so fast. Ask yourselves why the FAA
: >still requires backup instruments for GPS.
Mike Ciholas (mi...@ginger.lcs.mit.edu) wrote:
: [I thought this was no longer true. In any case there is a plan to
: eliminate this requirement, if it still exists.]
It is true, at least for now. To use my Garmin 155 in IFR, I must have a
working VOR. And if I need an alternate airport, the alternate must have a
non-GPS approach that I have the equipment to shoot it (and air and ground
equipment working). Tell us more about the plan to eliminate this.
And no, GPS isn't there yet. I've gotten RAIM warnings while shooting practice
approaches three times. Out of 15-20 approaches, that's not a great
percentage, is it?
Marc Rodstein
BGS...@prodigy.com
says...
>
>r...@mitre.org (Bob Noel) wrote:
>>
>>In article <3iu0bb$g...@enterprise.america.com>,
jpri...@america.com
>wrote:
>>
>>> >
limited
>>> > panel space cannot support both. I also cringe when
thinking
>>> > about the cost of an ADF receiver and the limited
performance
>>> > it offers.
>>> >
>>>
>>> Go with the GPS. This is a no-brainer.
>>
>>Hardly
>>
>>Maybe you should consider the (current) cost of an
IFR-certified
>>GPS receiver vs the expense of a used ADF then maybe you'll
figure
>>out why there is a debate. Depending on where you fly, an IFR
GPS
>>doesn't always offer an operational advantage. Also,
depending
>>on how often you fly, the payback for the current IFR GPS
receivers
>>might be a bit too long for some.
>>
>>
>>
>>Bob Noel aka Kobyashi Maru
>>WARNING: my email name may not work
>>My views are my own, not MITRE's
>>(why use a disclaimer when people are
>>too ---------- to understand it?)
>
ADF, as
>far as I'm concerned the ADF is in the junk pile. If you want
it, send
>be a check for $1000 and you're the new proud owner of a King
86. I
>don't know what you mean by "depending on where you fly" the
GPS doesn't .
>.offer any advantage. Were you kidding about this comparison?
OK, no
>flames here intended. With a GPS you have full position
awareness and
>navigational ability to any point in space without regard to
ground
>stations. It makes VHF navigation (VOR's) look absoultely
SICK! It makes
>ADF navigation look like stone age stuff. So it costs a bunch
of bucks.
>So did the aluminum air machine you go up in. So does your
funeral
>expense if you screw up. Do you fly IFR/IMC? or do you fly
IFR/VMC. If
>the latter, you need neither, if the former, I'd get two from
column A
>and none from column B. There is NO comparison betwee the two
that makes
>any sense. There is almost no comparison between the GPS and
the VOR/DME
>when it comes to accuray.
>But the ADF??? No way.
Mostly I agree with you. The only problem is, the ADF in my
plane is IFR
legal and the much more accurate GPS isn't!
--
Marc Rodstein
Boca Raton, Florida
Bob Noel
[snip]
> I beg to differ here, but owning both a GPS (VFR) as well as an ADF, as
> far as I'm concerned the ADF is in the junk pile. If you want it, send
> be a check for $1000 and you're the new proud owner of a King 86. I
> don't know what you mean by "depending on where you fly" the GPS doesn't .
> .offer any advantage. Were you kidding about this comparison? OK, no
> flames here intended. With a GPS you have full position awareness and
> navigational ability to any point in space without regard to ground
> stations. It makes VHF navigation (VOR's) look absoultely SICK! It makes
> ADF navigation look like stone age stuff. So it costs a bunch of bucks.
> So did the aluminum air machine you go up in. So does your funeral
> expense if you screw up. Do you fly IFR/IMC? or do you fly IFR/VMC. If
> the latter, you need neither, if the former, I'd get two from column A
> and none from column B. There is NO comparison betwee the two that makes
> any sense. There is almost no comparison between the GPS and the VOR/DME
> when it comes to accuray.
> But the ADF??? No way.
>
In my reply I specifically said "IFR GPS", and I also made
reference to the expense of the "current" lineup of IFR-certifible
GPS receivers.
Where I fly most every precision approach requires an ADF.
Since precision approach GPS receivers are not yet available, I need
an ADF if I want the ability to fly a precision approach (and I do
want that ability).
In terms of positional awareness, I have a decent LORAN receiver that
helps. Other folks make good use of VFR GPS receivers (panel mounted
or handheld). These are all much much more affordable than an
IFR-certified GPS receiver installation.
George Norris
> No, I don't buy the idea that GPS is more error prone because it's
>more "complex". An ADF may be simple from a theoretical standpoint, but if
>it breaks, no combination of black plastic tape, spare wire, and a
>leatherman tool is likely to fix it in the air. Given that, does it really
>matter how many fewer components it has than a GPS, or that it's completely
>analog, or that they've been making them for decades?
Amen! My lowly (non-IRF certified) GPS clearly informs me
when the signal is insufficient to navigation (3D fix, 2D
fix, or fix lost) even without RAIM or other sophisticated
error detection mandated by the FAA for IFR. Outside of
a very occasional loss of signal (this with an external
antenna lying on the glareshield), I find the position
reporting to be incredibly accurate.
Meanwhile my ADF using FAA certified NDB's can give pretty
accurate or wildly inaccurate indications without any precise
measure of accuracy (and monitoring the signal doesn't seem to
help). Depends on the time of day (ionospheric effects mainly),
terrain reflections, obstructions at the antenna site,
transmitter condition, and maybe the phase of the moon! Yes,
maybe I have a defective ADF although I have invested $$$ to
bring it up to snuff (King KR86) and many other pilots have
told me that it is one of the better ADF's they have seen!
At any rate, even though the GPS is more "complex", it
would seem to have a higher probablility of telling the
user that its navigational capabilities are compromised.
In that case, complex IS better!
==========================================================
George Norris PP-ASEL Archer II N8765C X = My Opinions
Motorola SPS Phoenix AZ Y = Motorola's
email: rxz...@email.sps.mot.com Note that X<>Y
Stan March
>
>Don't jump on the bandwagon so fast. Ask yourselves why the FAA
>position you can get into is you get into a false sense of
>security because you already think GPS is foolproof.
>
>
>the more places things could go wrong. It will take longer and
>be more expensive to validate, especially because there is so
>much to risk.
>
>you may not like that, but welcome to reality.
>
>--
>Head of Development
>Renaissance Knowledge Systems
>Englewood, Colorado
Ade, I'm from the school of hard knocks. I fly what some consider hard
IFR.
Do YOU fly or is this a theoretical expansion of thought?
Stan,
Head of the left seat,
IFR airplane in clouds,
Flying by GPS navigation.
NY,NY
No flame intended, but I'd like to cut the crap and get to people who
actually use the system, fly by it, see it's errors or capabilities, and
drop out those who only "teach". I would like to see information from
those who are in the airplane, flying in actual, in clouds, convective
activity, turbulance, icing, etc.
In MHO, no other votes count. IE, if you're theoretical, or whatever, and
you don't do it, then please don't even try to tell me or anyone else how
to do it.
On the other hand, if you've got good/great practical experience, then
please dump on us because we're all anxious to learn more and more.
Take care,
Stan
<=-----------------------=>
BGS...@prodigy.com
Arrow 2719C Islip NY (ISP)
<=-----------------------=>
Bob Noel
(Stan March) wrote:
[snip]
> No flame intended, but I'd like to cut the crap and get to people who
> actually use the system, fly by it, see it's errors or capabilities, and
> drop out those who only "teach". I would like to see information from
> those who are in the airplane, flying in actual, in clouds, convective
> activity, turbulance, icing, etc.
> In MHO, no other votes count. IE, if you're theoretical, or whatever, and
> you don't do it, then please don't even try to tell me or anyone else how
> to do it.
> On the other hand, if you've got good/great practical experience, then
> please dump on us because we're all anxious to learn more and more.
>
Stan: I don't feel it's valid to dismiss people's opinions, beliefs,
positions, whatever, simply because they don't fly IFR or even fly.
There are some folks out there that are designing and building some
real good equipment, but don't know how to fly. Maybe
they haven't had the time, maybe they haven't had the money. But
just because someone doesn't fly doesn't necessarily mean they don't
have any information that might be helpful to us instrument-rated pilots.
Stan March
Bob, if we're talking politics, religion, etc, I'd have no problem with
your position. When we talk flying an airplane, in weather, I don't give
much credibility to those who don't fly. Certainly an engineer can make a
statement about reliability and maintainability of an instrument, but
they cannot address the useability of that same device. A case in point
is the FAA's implementation of the GPS approach. In MHO, it sucks. It's
far too complex and does not need to be. Perhaps in a few years my
opinion will pervail or not. I know I can't change or alter the system.
I'm not fighting it either.
I believe that those who fly in the system have a far better
understanding of it, and frankly, I'm bored with academics who give me
the theory of why their soulution is right, but beg off when it comes to
putting the rubber down on the road. (Or is it their ass in the airplane
in IMC, turbulance?).
Since we're usually talking here about people launching airplanes into
clouds, with gusty wind conditions, possible icing, changing forcasts and
weather, is it too unreasonable to ask that those with aviation
experience lead the discussion? I think not, personally.
I welcome any and all information that makes me a better pilot. When it
comes to discussions, I welcome theoretical input. But I will always
lean towards the person who was there rather than the person who in
theory understood what was there when they weren't.
BTW, it's my ass in the left front seat with my passengers counting on my
experience and talent to bring them down with NO hassles. That's the way
I approach EVERY flight. I'm not knocking research, just putting it into
the place the I feel it resides in. Perhaps that's where our conflict
resides.
And GPS beats the crap out of ADF (Subject:GPS vs ADF). :-)
Fly safe,
Dan Taylor
ADF vs GPS. The ~$3000 cost of an ADF, lost panel space, installation, and
inherent lack of reliability of the hardware, not to mention the
operational problems for approach purposes, have all convinced me to
put away the KR86 brochures and pursue GPS.
I must believe that quite soon, the FAA will approve the use of GPS to
identify NDB positioning and in the implementation of non-precision approaches.
The complexity of modern technology is not a valid argument for not using it.
As an engineer, I would be more inclined to follow the path my GPS indicates,
rather than that of a servo looped, electromechanical motor driven indicator,
that is just as inclined to point me to the nearest lightning burst, or
supermarket neon lighting, than get me to the NDB.
Presently, when I am within 20 miles of the NDB, ATC might ask me to proceed
direct, and if conditions are on my side that day, I may get some indication
as to where that station is from my present heading. With GPS, the same
NDB could be 1000 miles away, and I can could advise ATC, of my ground speed,
track, ETE, and winds aloft are for the transition.
GPS is cheaper, lighter, more accurate, more informative, and in my estimation
much more reliable. Ask any radio shop what units they see the most on the bench.
A no brainer ... yes, but then I can't fly IFR legally or take my CFII checkride
in my plane without this dinosaur strapped to the fuselage.
It is just a matter of time.
Stan March
>
>Hey Stan you really want to sell that ADF? I might be interested.
>
>
>Jason Simpkins >^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>Hey Stan you really want to sell that ADF? I might be interested.
>
>
Yup, The thousand bucks will allow me to trade up my GPS-600 to an M3
which is IFR certified. The big space on the panel (which has NO space
now) will accomodate a nice GEM set of guages.
Plane is at Islip, NY, equipment inspectable on board.
Stan
Jason E Simpkins
Ade Barkah
: I must believe that quite soon, the FAA will approve the use of GPS to
: identify NDB positioning and in the implementation of non-precision
: approaches.
: It is just a matter of time.
Yes, it *is* just a matter of time, but somehow when I say
`the time isn't right now, it's not ready yet' people go
bezerk. =)
As far as the time-frame, after this year FAA will no longer
certify new GPS Cat I approaches. Within the next five years
FAA hopes to establish about 8,500 `precision' approach
overlays, although not to Cat I requirements (ie. worse).
That puts it to year 2001, about when NDBs and vor/vortacs
will be gradually taken off-line.
If we think about that for a moment... today we can do Cat
I, II and III approaches with our current equipment... in
5 years we'll do worse than Cat I, after buying new equipment.
-Ade Barkah
(hopefully this post will go through, we've been having problems
with our new news server)
ROSS SPATH
<<>}Newsgroups: rec.aviation.ifr
<<>}Organization: Prodigy Services Company 1-800-PRODIGY
<<>}Message-ID: <3j0ndk$g...@usenetw1.news.prodigy.com>
Stan,
What kind of GPS do you have, I am thinging of a hand held.
Thanks
Ross Spath :} compudata.com
---
* 1st 1.11 #6188 * Truck Pulls: for people who cannot understand the WWF
Jason E Simpkins
> In article <3j35hk$8...@usenetw1.news.prodigy.com>, BGS...@prodigy.com
> (Stan March) wrote:
>
> [snip]
>
>
> > No flame intended, but I'd like to cut the crap and get to people who
> > actually use the system, fly by it, see it's errors or capabilities, and
> > drop out those who only "teach". I would like to see information from
> > those who are in the airplane, flying in actual, in clouds, convective
> > activity, turbulance, icing, etc.
> > In MHO, no other votes count. IE, if you're theoretical, or whatever, and
> > you don't do it, then please don't even try to tell me or anyone else how
> > to do it.
> > On the other hand, if you've got good/great practical experience, then
> > please dump on us because we're all anxious to learn more and more.
> >
I do fly hard IFR and I use a IFR Cert GPS for enroute and in place of
a ADF. One thing that I have found is that the enroute part is great!
But beware if you file /G some controllers and tower foke will
question you....why? They don't know the rules so have your FARS out
and ready to recite. I have not experienced any malfunction yet with
the unit (King), and I've been in light iceing and some convective
areas. The unit is tied into a King HSI which makes it really nice.
Now, as a ADF replacement it is more difficult to use. It does give you
a "bearing" to the station but it is sometimes hard to picture your
position. I've experimented with some methods and have found that using
the bearing TO and Ground track cross referencing to be the best.
Shooting a approach with it IS more difficult if you don't have a
HSI/CDI needle to fly than a ADF needle. The plane I fly is a Beech
Travel Air BE-95. I short, I would like to see a RMI tied into a GPS
for situational awareness.....this then makes it practical for shooting
approaches, I'm not sure but I think you have to have a mechanical CDI
of some sort for IFR cert in your plane???
Jason Simpkins
Ade Barkah
: Do YOU fly or is this a theoretical expansion of thought?
: Stan,
I don't know why this is getting personal, but yes, Stan,
I fly, with GPS even, but not in the soup, because neither
the GPS we have nor the Katana it is in is IFR certified.
Stop by APA and have a drink on me if you're in Denver.
-Ade Barkah
[hopefully our news server will pass not die again]
--
NOSIG
Andrew Boyd
about adf vs gps:
>I am very interested in the ADF vs GPS debate, as my limited
>panel space cannot support both. I also cringe when thinking
>about the cost of an ADF receiver and the limited performance
>it offers.
I just can't resist: which is cheaper: a $2k terra adf, or a $5k
(ifr) garmin gps? (both legal for ifr, please) Which is going
to cost more to install?
re: limited performance of adf - most people out there are using
really old adfs. They maybe weren't great when they were new, and
20 years of being in the panel hasn't exactly improved their
performance.
>My instrument training was a rather smooth process, and NDB
>approaches came very easily. I would like to credit my
>engineering and math background, but then that wouldn't
>support why I could not figure out reciprocal headings
>and compass only turns to heading. My brain turned to mush
>on the simplest of addition/subtraction problems.
add 200, subtract 20
subtract 200, add 20
>On most NDB approaches, in actual conditions we had to revert
>to localizer approaches if available. On one approach into
>CVO (Corvallis, Oregon) the controller vectored me to the
>NDB because I could not receive it until I was 5 miles from
>it. Turns out, that the receiver was not aligned properly
see above. Ponder this for a moment: just because most adfs
are old does not mean that they all don't work.
I personally find it odd that you folks down south that insist
on some anal 30-day vor check (for ifr) feel confident blasting
off into the clag with an antique adf that hasn't been turned
on in six months. Really weird.
Any doubt in your mind, "swing" the adf on the ground, as you
would a compass. An ndb off the end of the runway helps lots.
More than 5 degrees of adf system error, do you really wanna do
an approach with this thing?
>Now, since GPS positioning give you all the nav information
>that the ADF does, with much more ...
This is a legal question, not a technical one. My suggestion
for a low-budget panel would include in addition to a vor with
glide slope would be a functional (!) adf, and a vfr loran or gps.
ifr gps's are too much money right now. I'm waiting for the
prices to drop on the TSO C-129 units.
Until then, no one said that you had to turn off your vfr loran
or your vfr gps during an ndb approach, for gosh sakes.
Data point: I'm an active canadian instrument instructor who
regularly files ifr on lf airways, and who's home airport only
has (one) ndb approach.
--
#include <std.disclaimer>
Daniel Taylor
>Dan Taylor <d...@aviator.tessi.com> wrote some time ago (sorry)
>about adf vs gps:
>I just can't resist: which is cheaper: a $2k terra adf, or a $5k
>(ifr) garmin gps? (both legal for ifr, please) Which is going
>to cost more to install?
>I personally find it odd that you folks down south that insist
>on some anal 30-day vor check (for ifr) feel confident blasting
>off into the clag with an antique adf that hasn't been turned
>on in six months. Really weird.
>This is a legal question, not a technical one. My suggestion
>for a low-budget panel would include in addition to a vor with
>glide slope would be a functional (!) adf, and a vfr loran or gps.
YOU MISSED THE POINT OF MY DISCUSSION.
A VFR $1000 hand-held GPS yields a better indication as to where
the NDB is, than a $10000 ADF. It is the difference in technology
and methodology that should drive this discussion. ADF technology
is archaic, error prone, and yields a very limited range of useful
navigational data.
I do not need an IFR GPS to direct me to the NDB, compute GS,
display TRACK angle, compute turn anticipation, ad nauseum.
While you might be able to pose an argument that VFR GPS
does not implement a RAIM algorithm, I would think the same
could be said of the probability of lightning and external
noise source interference, stuck ADF indicator, improperly
set DG, or the questionable integrity and reliability of
the NDB itself. If you investigated the use of GPS in all industry,
you might be surprised at the scope of its influence and impact
on all of our lives.
I appreciate your opinion and your desire to spend $2K on an ADF,
pay the fee for installation, and give up the panel space for the
indicator. I still maintain that a $2K GPS, with or without moving
map functionality, is a wiser, more accurate, and ultimately
cheaper purchase.
My original statements were that not only is the technology out-dated,
the NDB approach methodology contains too many sources of error.
Time and the FAA will ultimately tell ...
dan
Stan March
What's a /G filing in the flight plan. (/R?).
Stan
Stan March
It's real easy to take words out of context, and probably easier to do it
electronically. Perhaps I am a bit reactive to other's editing.
Opinionated maybe,
and the reciprocal offer to you, at Islip, New York.
Take care,
Stan
Stan March
We fly with the Northstar GPS600, a VFR only gps with a changable
database.
If you flew the Loran M1, this is the same but better. In the year plus
we've owned it it has never given any alert signals (loss of signal), and
has been fantastically accurate. We'd like to trade up to the M3 IFR
certified model and are only waiting for the lottery to hit.
Stan
Alex France
>A VFR $1000 hand-held GPS yields a better indication as to where
>the NDB is, than a $10000 ADF. It is the difference in technology
>and methodology that should drive this discussion. ADF technology
>is archaic, error prone, and yields a very limited range of useful
>navigational data.
This reminds me of a question I have wondered about for some time -
Why is this so? Why are ADF receivers based on such technology? As I
understand it even the more modern units still rely upon motorized
movement of coils within the indicator unit in order to 'remote' the
rotation of one of the antennas. Clearly more modern displays LCD or
LED based could be used and there are many alternatives for the
receiver electronics available, but what about the equivalent to
this rotating coil? Does anyone know of a non-moving parts way of
doing this?
Alex, AA5 G-BEZI.
John Stanley
Stan March <BGS...@prodigy.com> wrote:
>Now for the killer comparison. Navigating IFR in heavy convective
>activity.
Yes, a good comparison. It would take the heavy turbulence to cancel out
the radical variations in position GPS reports.
Yesterday, the building I work in was reported by GPS as moving due east
at almost 8 miles per hour. I still feel the pain of slamming into the
pavement when a different GPS had me rising into the air almost 600 feet
and then diving 200 feet underground, all during about 30 seconds while
standing in the parking lot.
Ron Natalie
: In article <1995Mar8....@crosfield.co.uk>, a...@crosfield.co.uk
: (Alex France) wrote:
: The more modern ADFs (e.g. the KR87?) use three (or is it just two?)
: mutally perpendicular ferrite rods as sensors for the MF/LF signal. The
: amplitudes (and phases?) of the signals are compared to give a relative
: bearing for the signal. The indicator is still motor-driven in many
: cases, but nothing outside the cockpit moves.
Gee, my KR86 definitely has something whirring away outside the aircraft
when it runs.
-Ron
Julian Scarfe
> This reminds me of a question I have wondered about for some time -
> Why is this so? Why are ADF receivers based on such technology? As I
> understand it even the more modern units still rely upon motorized
> movement of coils within the indicator unit in order to 'remote' the
> rotation of one of the antennas. Clearly more modern displays LCD or
> LED based could be used and there are many alternatives for the
> receiver electronics available, but what about the equivalent to
> this rotating coil? Does anyone know of a non-moving parts way of
> doing this?
The more modern ADFs (e.g. the KR87?) use three (or is it just two?)
mutally perpendicular ferrite rods as sensors for the MF/LF signal. The
amplitudes (and phases?) of the signals are compared to give a relative
bearing for the signal. The indicator is still motor-driven in many
cases, but nothing outside the cockpit moves.
[You can see by the ? marks that I don't know an awful lot about it! I
found out when I asked the same question as Alex. Anybody got more
details on the modern ADF?]
Julian Scarfe
ja...@cus.cam.ac.uk
Alex France
>Gee, my KR86 definitely has something whirring away outside the aircraft
>when it runs.
Our KR85 definitely doesn't. I had to remove the combined loop/sense antenna
once and as far as I know it consists of just coils/ferrite and an FET
front end amplifier - no movin' bits. The FET amplifiers are renowned for
blowing and since the whole lot is encased in epoxy this means you are
looking at a new antenna (at great expense) when it blows.
Alex, AA5 G-BEZI.
William W. Plummer
Call me a Ludite if you want, but I have alot of respect for the old
synchro/selsyn/resolver/motor technology. It is SIMPLE and relies on
magnets aligning with magnetic fields. It is ROBUST with no high
impedance FETs to blow, just low Z coils and wires. I suspect its
weakness might be in bearings getting dirty and binding up, but I don't
actually know. --Bill
----
William W. Plummer C, MASM, dBASE to your spec.
7 Country Club Dr. plu...@altamira.theme.com
Chelmsford, MA 01824 PP-ASEL, N1NGK, MA RE Broker
Home: 508-256-9570 (leave msg.) @TALL FASHIONS: 508-251-8844
STUART M. TOMARES
knew this for years already. It's a Garmin 95XL and on NAV screen has
bearing to the fix (BRG), Ground Speed (GS), ETE, and DIStance. I
changed the setup, so ETE is changed to TRK (ground track). Thence, when
turning toward the bearing, needle centered on the airway (or on the
approach) for example, you simply keep turning (L or R) until the unit
registers a TRK the same as the BRG and you have an instant, perfect wind
corection angle. Thence, just fly the reference heading. Tried it a few
times today flying Victor airways, and it worked great. Once the TRK was
the same as BRG, I flew the indicated heading, and needles remained
centered quite well.
I know we should all be great at bracketing, etc... but this use of the
GPS pointed out just another way that these gadgets can be *really*
useful.
-- Stuart Tomares (PP-ASEL-IA)
Jason E Simpkins
Yup, found this out myself....but the neatest thing is that with a GPS/
loran anypoint in space becomes a VOR with radials coming off of it.
But the most usefull I think is in turning towards a Bearing or radial
because you know exactly what radial or bearing your on during the
interception, kinda like a digital VOR (DVOR) would. So five degrees
before interception you can start your roll out and make perfect on
track corrections. So it does work like a digital RMI/VOR needle in
this case for a vor radial.
Jason Simpkins