ADF and GPS equip %

"Peter" wrote in message ...

"Julian Scarfe" wrote

Really? Is it common to attempt to plan a flight and be unable to find a
sensible alternate that has an ILS, VOR or radar approach without a DME
requirement?

Not having done a survey of U.S. approach plates, I have no idea,
which is why I was posting, seeking a comment from the residents here,
who are nearly all American.

A DME seems a useful thing relative to the panel space and cost,
whereas many would agree an ADF is much less useful.

There are still parts of the world where NDBs are the only en route
navaids receivable, but that isn't going to bother most people reading
this.

Peter, I'm one who worried about removing my DME, but I did so, anyway.
It has turned out to be a non-issue, at least partly because:
1. My CNX80 displays horizontal distance to its tuned VOR station.
2. My CNX80 displays distance to the runway for approaches.
(That's separate from the distance to the next waypoint on an approach.)
I think I did the right thing by keeping my ADF and removing my DME.

In a plane used for training, there's a much more serious reason to tear
out the ADF. If you go for an instrument rating checkride in a plane
that
has an ADF in it, the examiner can (and probably will) ask to see an
NDB
approach flown. Maybe even partial panel. Which means you need to
train
students to fly partial panel NDB approaches (and holds). What a
frigging
waste of time and money.

IME, a proficient IFR pilot (even a student) can learn the NDB approach
and hold in an hour or two, max. Partial panel might take another hour
or two (or not) but my experience is that examiners rarely ask for a
P/P NDB approach these days without allowing the use of a VFR GPS for
situational awareness (which is, after all, the norm in today's
cockpit).

There are many reasons that instructors don't see this happens, and IMO
they are not good ones.

There are the students who really don't get the subtle differences
between heading, bearing, course, and track. They haven't really got
the situational awareness thing all down. IMO they're dangerous - not
just when the magic box fails, but in general. They probably represent
most of the private-IFR population, but the private-IFR population has
a pretty crappy record when it comes to handling real IFR - the kind
you can't reasonably scud run.

It's sort of like the taildragger transition. A pilot who understands
what landings are about can just sit down in a simple taildragger with
good visibility like a Champ and fly it, even lacking any tailwheel
experience. One who drives the airplane onto the runway can't - he may
easily need more hours to check out in a taildragger than he needed for
the initial solo.

In addition to the issue of pilot skill, there is the issue of the
equipment. RMI is expensive, but a movable card is dirt cheap, common
- but somehow not universal. Why not? Without it, you're constantly
doing mental math, remembering your heading - it's a pain. It's almost
the equivalent of making the transition into a blind taildragger - yes,
it can be and was done, but these days there's no reason for it.

Finally, the equipment needs to work. That means the heading gyro
needs to have reasonable precession (if you can't set it turning
initial and not worry about it until established in the miss, that's
NOT reasonable - people who routinely fly hard IFR won't tolerate it
unless they've equipped the cockpit with moving maps and no longer care
about the heading) and if the ADF is not equipped with a moveable card,
a heading bug is required equipment. The compass must work properly on
all headings, with no more than a few degrees error on any. If you're
going to do it right, either the DG needs to be a barrel or the compass
needs to be a card - mixing types is a recipe for confusion, but too
common these days. And finally, the ADF must point straight and strong
at the FAF or FAP - meaning that from 5-10 miles away, you need to have
a needle with an error no more than 2/5 of your tolerance - straight or
turning - just like VOR. So if you're shooting for +/-10 degrees, the
ADF can err by no more than 4 degrees in straight flight at any
reasonable correction angle, and it can't lag more than 1.3 degrees in
a standard rate turn.

I have seen an ADF-equipped IFR rental like that. ONCE.

ADF is not cheap. Crappy, barely serviceable ADF that makes students
believe that consistenly shooting one is impossible is cheap. And
unfortunately, too many CFII's don't know the difference.

In this day and age, the typical function of an ADF is to allow the
pilot to use his VFR GPS as an IFR unit, and not have to spring for an
IFR GPS. In theory, he us shooting an NDB approach, using the ADF for
the marker, etc - but in reality it's all VFR GPS. We keep up the
illusion because we don't want to spend the money to maintain these
things, and we don't feel IFR GPS offers good value compared to VFR
GPS.

Michael

"Peter" wrote in message ...

"John R. Copeland" wrote

An RMI presentation, with the ADF pointer on an HSI, not only provides
the positional awareness Jose praises, but it also vaporizes much of
Roy's concern about difficulties in teaching NDB approaches.
The examiner can't demand an NDB approach without the HSI,
and the RMI presentation makes NDB approaches very intuitive.
HSIs are extremely nice instruments, either stand-alone or in PFDs.

...

I am not sure where an HSI comes into NDBs. I think you mean an RMI.
No HSI I know of can show a track error from an NDB. It can do VOR,
LOC, or GPS. Perhaps you mean an EHSI like the Shadin or Honeywell?


I said "...an ADF pointer on an HSI..."
The RMI presentation is then integrated with the HSI.
That references the ADF pointer to compass directions *and* heading.
In fact, my HSI is magnetically slaved, which is even another nice feature.
It's part of my Collins FD101 Flight Director.

On 1 Apr 2006 13:44:46 -0800, "Michael"
wrote:

ADF is not cheap. Crappy, barely serviceable ADF that makes students
believe that consistenly shooting one is impossible is cheap. And
unfortunately, too many CFII's don't know the difference.

Good ADF certainly is not cheap. Mooney's charge for the Becker ADF add-on
option in the Ovation 2GX is $15,500!

But sometimes the problem lies elsewhere. I've got a cheap ADF in my a/c
(it's the King model that has an integrated pointer in the box). It works
fine on the ground with the engine off. But, due to its design, the
voltage regulator puts out so much interference that gets picked up by the
ADF to render it of marginal utility in the air. (I kept it because that's
the only method of receiving the local altimeter setting at my home base).

Oh, and I can't change the voltage regulator type because of STC issues.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

But sometimes the problem lies elsewhere. I've got a cheap ADF in my a/c
(it's the King model that has an integrated pointer in the box). It
works
fine on the ground with the engine off. But, due to its design, the
voltage regulator puts out so much interference that gets picked up by
the
ADF to render it of marginal utility in the air.

But a good ADF installation would not have this problem. I bet the
$15K unit from Becker is immune to this sort of noise. In the old
days, part of the installation process was checking for interference
from external sources and getting rid of it. Nobody will pay for that
anymore,

The real glory of GPS is not how accurate it is (that level of accuracy
is rarely needed) but how immune it is to installation/interference
issues. Hnadheld ADF, anyone?

Michael

On 2 Apr 2006 13:13:51 -0700, "Michael"
wrote:

But sometimes the problem lies elsewhere. I've got a cheap ADF in my a/c
(it's the King model that has an integrated pointer in the box). It
works
fine on the ground with the engine off. But, due to its design, the
voltage regulator puts out so much interference that gets picked up by
the
ADF to render it of marginal utility in the air.

But a good ADF installation would not have this problem. I bet the
$15K unit from Becker is immune to this sort of noise. In the old
days, part of the installation process was checking for interference
from external sources and getting rid of it. Nobody will pay for that
anymore,


That's true. The ADF was in the airplane when I purchased it. At the
time, I rarely flew an NDB approach and, when I did, it was at a higher
frequency and worked OK. It's been the combination of lower freq NDB's
that I'd been using more frequently since moving to this area (260 and
lower) along with the alternator STC that have resulted in the problem
cropping up.

I'd guess that even the more expensive King ADF would be immune to this
sort of problem. It has an "active antenna" which costs more than my ADF
would have cost.


The real glory of GPS is not how accurate it is (that level of accuracy
is rarely needed) but how immune it is to installation/interference
issues. Hnadheld ADF, anyone?


And the immunity is especially surprising considering the weak signals
being detected.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

I came across the same question recently, as I happened in one day to see
three Cessna panels with full-on Garmin panels but no ADF. So I did an
informal look at Trade-A-Plane, which confirms the tendancy. I get the
impression that a good 50% of those overhauling their panel chose to
chuck the ADF, and the proportion of new panels delivered (pre-G1000)
without ADF is similar, if not higher.

This puzzles me, because of the number of approaches still published with
ADF requirement - why spend thousands to have the latest and greatest,
if it's to restrict your use of so many approaches? I'm aware that many
instrument students prefer not to have it, because if it's there they
will be asked to demonstrate proficiency with it on the checkride - yet
I fail to understand just why this requirement strikes terror in peoples'
hearts!

I am also saddened to see the DME go, which seems to be part of the same
trend, though I do accept the argument that with a G430 and a G530
stacked in the panel you're hardly getting any more information from a
DME!

As for RMI - sure it's great to have a VOR/NDB RMI for your DME arcs etc,
but how many piston singles actually have this? I see them in KingAirs,
but not in 172's.

GF

Greg,

This puzzles me, because of the number of approaches still published with
ADF requirement - why spend thousands to have the latest and greatest,
if it's to restrict your use of so many approaches?


Because you can (in the US) legally use an approach-certified GPS instead of
the ADF for those approaches?

--
Thomas Borchert (EDDH)

In a small GA plane, THE panel to have has, an IFR GPS, a VOR/GS, a
radio, a transponder and an all electric autopilot. You fly the GPS for
enroute and then take the ILS or VOR approach. If your vacuum fails you
still have your autopilot, and if your electric fails you still have
your vacuum. Back this up with a handheld radio and a handheld GPS and
you are set to go.

No need for ADF, DME, or marker beacons. They are all avionics of the
past. No need for an HSI becuase you have the autopilot coupled to the
GPS.

Another good reason to get rid of all the extra stuff is repair. The
less you have, the less you need to repair.

In article ,
says...


Greg,

This puzzles me, because of the number of approaches still published with
ADF requirement - why spend thousands to have the latest and greatest,
if it's to restrict your use of so many approaches?


Because you can (in the US) legally use an approach-certified GPS instead of
the ADF for those approaches?


Well, that "almost" works. To fly it, you just need RAIM - to "file" it (if you
have G-430/530 type equipment) you also need the working ADF in the plane.
That's why I used the word "restrictions". You might be fine under many or most
circumstances, but it can put a kink in your plans if you want to file IFR to
an out-of-the-way airport that has an ADF requirement. Then you realize if you
had kept your 1965 panel you could file it . . .

Perhaps pilots are simply assuming those ADF requirements will all be gone
soon.

GF