primary flight instruments on partial panel

[Greg[_1_]]

In primary and supporting method of attitude instrument flying, which
do you consider the primary instrument for bank in the partial panel
situation (loss of both attitude indicator and heading indicator)?
Turn coordinator or magnetic compass?
thank you
Greg
greggordon.org/flying

[Jim Macklin]

You would use the TC or TB to control bank angle, it is the
instrument that you control, therefore primary. You monitor
the compass to fly a heading which is the desired result.
Using the compass as a control instrument generally requires
a south heading so that the compass turning error is in the
correct direction.


--
James H. Macklin
ATP,CFI,A&P

"Greg" > wrote in message
ups.com...
| In primary and supporting method of attitude instrument
flying, which
| do you consider the primary instrument for bank in the
partial panel
| situation (loss of both attitude indicator and heading
indicator)?
| Turn coordinator or magnetic compass?
| thank you
| Greg
| greggordon.org/flying
|

[Roy Smith]

Greg > wrote:
>In primary and supporting method of attitude instrument flying, which
>do you consider the primary instrument for bank in the partial panel
>situation (loss of both attitude indicator and heading indicator)?
>Turn coordinator or magnetic compass?

The magnetic compass isn't worth **** in a turn. It should only be
used as a heading reference in straight-and-level flight.

If you've got a good ADF you can tune in an AM broadcast station and
that makes a dandy DG replacement. Pick a station that's far enough
away that azimuth to the station is approximately constant but close
enough that you get a good strong signal. Not that most planes have
ADFs these days, and the ones that do exist tend to be pretty cruddy.

With practice, you can fly a decent ILS with just a TC, ASI, and CDI.
No AI, no DG, not even a wet compass.

[Robert M. Gary]

Roy Smith wrote:
> Greg > wrote:
> >In primary and supporting method of attitude instrument flying, which
> >do you consider the primary instrument for bank in the partial panel
> >situation (loss of both attitude indicator and heading indicator)?
> >Turn coordinator or magnetic compass?
>
> The magnetic compass isn't worth **** in a turn. It should only be
> used as a heading reference in straight-and-level flight.

Actually compass turns are taught of all instrument pilots. An
instrument pilot should be able to tell you what the compass will
indicate in a turn and be able to turn to exact headings using just the
compass. For most places in the U.S. the correction is +30/-30. See
page 5-25 of the FAA's "Instrument Flying Handbook"
http://www.faa.gov/library/manuals/aviation/instrument_flying_handbook/media/faa-h-8083-15-1.pdf

"...For example, when turning from an easterly direction to north,
where the latitude is 30°, start the roll-out when the compass
reads 37° (30° plus one-half the 15° angle of bank, or
whatever amount is appropriate for your rate of roll-out).
When turning from an easterly direction to south, start the
roll-out when the magnetic compass reads 203° (180° plus
30° minus one-half the angle of bank). When making similar
turns from a westerly direction, the appropriate points at
which to begin your roll-out would be 323° for a turn to
north, and 157° for a turn to south...."


-Robert, CFII

[Bob Gardner]

If I had my druthers, compass turns would be eliminated from training and
timed turns used instead. The PTS does not require compass turns, but most
CFII's teach them anyway. I'll bet my life on a timed turn, but not on a
compass turn.

Whenever this question arises I postulate this scenario: It is a dark and
stormy night, ice is beginning to become apparent, the wife's knuckles are
white and the kids are crying. The heading indicator craps out and the mag
compass looks like a washing machine. What a fine time to be determining
leads and lags and remembering rules.

Bob Gardner
"Robert M. Gary" > wrote in message
ups.com...

Roy Smith wrote:
> Greg > wrote:
> >In primary and supporting method of attitude instrument flying, which
> >do you consider the primary instrument for bank in the partial panel
> >situation (loss of both attitude indicator and heading indicator)?
> >Turn coordinator or magnetic compass?
>
> The magnetic compass isn't worth **** in a turn. It should only be
> used as a heading reference in straight-and-level flight.

Actually compass turns are taught of all instrument pilots. An
instrument pilot should be able to tell you what the compass will
indicate in a turn and be able to turn to exact headings using just the
compass. For most places in the U.S. the correction is +30/-30. See
page 5-25 of the FAA's "Instrument Flying Handbook"
http://www.faa.gov/library/manuals/aviation/instrument_flying_handbook/media/faa-h-8083-15-1.pdf

"...For example, when turning from an easterly direction to north,
where the latitude is 30°, start the roll-out when the compass
reads 37° (30° plus one-half the 15° angle of bank, or
whatever amount is appropriate for your rate of roll-out).
When turning from an easterly direction to south, start the
roll-out when the magnetic compass reads 203° (180° plus
30° minus one-half the angle of bank). When making similar
turns from a westerly direction, the appropriate points at
which to begin your roll-out would be 323° for a turn to
north, and 157° for a turn to south...."


-Robert, CFII

[Robert M. Gary]

Bob Gardner wrote:
> If I had my druthers, compass turns would be eliminated from training and
> timed turns used instead. The PTS does not require compass turns, but most
> CFII's teach them anyway. I'll bet my life on a timed turn, but not on a
> compass turn.

Funny, I think compass turns are much easier under stressful
situations. Having to start and stop the clock and compute the time
necessary for the turn while holding an exact standard rate turn would
be hard. Of course, in most situations, turning within 1degree is not
required.

-Robert

[Jose[_1_]]

> Funny, I think compass turns are much easier under stressful
> situations. Having to start and stop the clock

I disagree. A quick calculation tells me where the second hand should
be when I'm done. I roll out, then make little corrections as needed.

Jose
--
The monkey turns the crank and thinks he's making the music.
for Email, make the obvious change in the address.

[Jim Macklin]

If you're down to just the compass, worry more about keeping
the wings "level" and less about heading. The compass, in
the northern hemisphere will work as the sole instrument
only when flying south [saw between 150-210] heading. It
will be very sensitive and indicate the correct turn
direction.

If you fly very much IMC, spend the money for Sporty's
battery powered AI. And keep the needle/ball-TC too.


--
James H. Macklin
ATP,CFI,A&P


"Jose" > wrote in message
m...
|> Funny, I think compass turns are much easier under
stressful
| > situations. Having to start and stop the clock
|
| I disagree. A quick calculation tells me where the second
hand should
| be when I'm done. I roll out, then make little
corrections as needed.
|
| Jose
| --
| The monkey turns the crank and thinks he's making the
music.
| for Email, make the obvious change in the address.

[Andrew Sarangan[_1_]]

I don't like purely timed turns because I rarely get them to work
accurately. It takes time to bank into the turn and bank out and any
inaccuracies in holding a standard rate turn you can be off by 20 or 30
degrees. Using compass turns, even if don't compensate for banking
errors you will only be off by 30 degrees. What I teach is to make
large turns using the compass turns (with or without banking errors),
and then make fine adjustments. In a sense this is a combination of
compass turns and timed turns, except you don't start and stop a clock.
You time the fine adjustments in your head.



Bob Gardner wrote:
> If I had my druthers, compass turns would be eliminated from training and
> timed turns used instead. The PTS does not require compass turns, but most
> CFII's teach them anyway. I'll bet my life on a timed turn, but not on a
> compass turn.
>
> Whenever this question arises I postulate this scenario: It is a dark and
> stormy night, ice is beginning to become apparent, the wife's knuckles are
> white and the kids are crying. The heading indicator craps out and the mag
> compass looks like a washing machine. What a fine time to be determining
> leads and lags and remembering rules.
>
> Bob Gardner
> "Robert M. Gary" > wrote in message
> ups.com...
>
> Roy Smith wrote:
> > Greg > wrote:
> > >In primary and supporting method of attitude instrument flying, which
> > >do you consider the primary instrument for bank in the partial panel
> > >situation (loss of both attitude indicator and heading indicator)?
> > >Turn coordinator or magnetic compass?
> >
> > The magnetic compass isn't worth **** in a turn. It should only be
> > used as a heading reference in straight-and-level flight.
>
> Actually compass turns are taught of all instrument pilots. An
> instrument pilot should be able to tell you what the compass will
> indicate in a turn and be able to turn to exact headings using just the
> compass. For most places in the U.S. the correction is +30/-30. See
> page 5-25 of the FAA's "Instrument Flying Handbook"
> http://www.faa.gov/library/manuals/aviation/instrument_flying_handbook/media/faa-h-8083-15-1.pdf
>
> "...For example, when turning from an easterly direction to north,
> where the latitude is 30°, start the roll-out when the compass
> reads 37° (30° plus one-half the 15° angle of bank, or
> whatever amount is appropriate for your rate of roll-out).
> When turning from an easterly direction to south, start the
> roll-out when the magnetic compass reads 203° (180° plus
> 30° minus one-half the angle of bank). When making similar
> turns from a westerly direction, the appropriate points at
> which to begin your roll-out would be 323° for a turn to
> north, and 157° for a turn to south...."
>
>
> -Robert, CFII

[Robert M. Gary]

Jim Macklin wrote:
> If you're down to just the compass, worry more about keeping
> the wings "level" and less about heading. The compass, in
> the northern hemisphere will work as the sole instrument
> only when flying south [saw between 150-210] heading. It
> will be very sensitive and indicate the correct turn
> direction.

I'm not sure I follow. During my CFII training I got a solid 2 hours of
flying partial panel with compass turns. I was able to fly exact
vectors to ILS, etc. If I was off even by 2 degrees when I rolled out
on a heading my CFII would yell at me. I can tell you from experience
you 100% can fly very, very exact headings in any direction using
compass turns if you know how to read the compass and account for the
effects. I'm not saying doing so in IMC would be as easy as it is under
the hood but personally, I would do that in a second before trying to
do the math required of timed turns while under the pressure of partial
panel IMC. Of course most of us have GPSs which are actually a much
better partial panel way to figuring heading (approximated as course).

-Robert, CFII

[Jim Macklin]

I'm speaking of the question by the OP, which seemed to be
asking if all you had was the compass or the TC [needle],
which would be primary.

The compass gives 0 [zero] bank angle indication and in a
steep turn may not rotate at all. Controlling the airplane
can be done with the TC plus some pitch instrument.
Controlling the airplane with ONLY the compass is much more
difficult because it indicates reverse turn direction on all
headings except near 180 degrees (northern hemisphere).

Very few airplanes have the mag compass located where it can
be flown as sole reference, most are mounted on the
windshield post.


--
James H. Macklin
ATP,CFI,A&P

"Robert M. Gary" > wrote in message
oups.com...
|
| Jim Macklin wrote:
| > If you're down to just the compass, worry more about
keeping
| > the wings "level" and less about heading. The compass,
in
| > the northern hemisphere will work as the sole instrument
| > only when flying south [saw between 150-210] heading.
It
| > will be very sensitive and indicate the correct turn
| > direction.
|
| I'm not sure I follow. During my CFII training I got a
solid 2 hours of
| flying partial panel with compass turns. I was able to fly
exact
| vectors to ILS, etc. If I was off even by 2 degrees when I
rolled out
| on a heading my CFII would yell at me. I can tell you from
experience
| you 100% can fly very, very exact headings in any
direction using
| compass turns if you know how to read the compass and
account for the
| effects. I'm not saying doing so in IMC would be as easy
as it is under
| the hood but personally, I would do that in a second
before trying to
| do the math required of timed turns while under the
pressure of partial
| panel IMC. Of course most of us have GPSs which are
actually a much
| better partial panel way to figuring heading (approximated
as course).
|
| -Robert, CFII
|

[David Cartwright]

"Greg" > wrote in message
ups.com...
> In primary and supporting method of attitude instrument flying, which
> do you consider the primary instrument for bank in the partial panel
> situation (loss of both attitude indicator and heading indicator)?
> Turn coordinator or magnetic compass?

The turn co-ordinator is your primary measure of bank, for a couple of
reasons. First, the compass doesn't measure bank angle - it just shows what
direction you're pointing in - whereas the TC does show the degree to which
you're banked. Second, and most importantly, because of the way it's put
together, the compass doesn't turn steadily, and so it'd be wrong to fool
yourself into thinking that the faster the compass was moving, the more
you're banked.

Have a go one day and you'll see. Take someone competent with you to look
out of the window, get to a safe place and height, make sure your DI's set
correctly, and do a rate-one turn through 720 degrees or more (go around as
much as you like, in fact). In the northern hemisphere at least, you'll note
that when the DI goes through 090 or 270, the compass stands a fair chance
of agreeing with the DI. As you go through north, though, the compass will
under-read, and as you go through south, it'll over-read. The only time you
can rely on the compass is when going in a straight line - which is why you
always check and adjust your DI when flying in a straight line.

Hence if you want to do a partial-panel turn in IMC, you fly straight and
check the compass, then do a rate-one turn (the turn co-ordinator shows you
the bank angle) for the required number of seconds - three degrees per
second for a rate-one turn, of course. You then level out, give the compass
a few seconds to stop wiggling, and then adjust your heading if you're a
little bit out. I seem to recall in the IMC rating test you have to get to
within five or ten degrees of the desired heading with one initial turn and
one "fine tune" adjustment - which is generally pretty achievable.

David C

[Allen[_1_]]

"David Cartwright" > wrote in message
...
> "Greg" > wrote in message
> ups.com...
>> In primary and supporting method of attitude instrument flying, which
>> do you consider the primary instrument for bank in the partial panel
>> situation (loss of both attitude indicator and heading indicator)?
>> Turn coordinator or magnetic compass?
>
> The turn co-ordinator is your primary measure of bank, for a couple of
> reasons. First, the compass doesn't measure bank angle - it just shows
> what direction you're pointing in - whereas the TC does show the degree to
> which you're banked.

The turn coordinator shows direction and rate of turn but no bank angle.
You can do a skidding standard rate turn with the wings level by applying
rudder in one direction and opposite aileron to keep the wings level. In a
coordinated turn it does somewhat show bank angle but the faster your
airspeed the more bank angle is required to achieve standard rate.

I agree with using the TC over the compass if it is avalable. Following is a
quote out of the Wikipedia, for what it's worth:
"Aircraft compass turns are used in an aircraft when other directional
instruments, such as the directional gyro or turn coordinator, have failed."
http://en.wikipedia.org/wiki/Aircraft_compass_turns


Allen

[Jose[_1_]]

> whereas the TC does show the degree to which
> you're banked.

The TC does not show bank. It shows rate of turn, and has a temporary
indication of bank intended to "lead" the turn indication. If you slip
or skid, the TC will shortly indicate "straight" (non turning) flight.
Even though you are banked, you are going straight.

Nonetheless, it's what I would use as primary, if I only had that and
the whiskey compass.

Jose
--
The monkey turns the crank and thinks he's making the music.
for Email, make the obvious change in the address.

[Gary Drescher]

"Jose" > wrote in message
t...
>> whereas the TC does show the degree to which you're banked.
>
> The TC does not show bank. It shows rate of turn, and has a temporary
> indication of bank intended to "lead" the turn indication. If you slip or
> skid, the TC will shortly indicate "straight" (non turning) flight. Even
> though you are banked, you are going straight.
>
> Nonetheless, it's what I would use as primary, if I only had that and the
> whiskey compass.

Yup. The crucial point is that the inclinometer tells you about slipping or
skidding. So if it's centered, then the TC indeed tells you whether you're
banked or level.

--Gary

[Robert M. Gary]

David Cartwright wrote:
> "Greg" > wrote in message
> ups.com...

> The turn co-ordinator is your primary measure of bank, for a couple of
> reasons. First, the compass doesn't measure bank angle - it just shows what
> direction you're pointing in - whereas the TC does show the degree to which
> you're banked. Second, and most importantly, because of the way it's put
> together, the compass doesn't turn steadily, and so it'd be wrong to fool
> yourself into thinking that the faster the compass was moving, the more
> you're banked.

In a full panel your primary bank is, of course, your heading indicator
in straight flight. Yet it also does not indicate bank angle.

> Have a go one day and you'll see. Take someone competent with you to look
> out of the window, get to a safe place and height, make sure your DI's set
> correctly, and do a rate-one turn through 720 degrees or more (go around as
> much as you like, in fact). In the northern hemisphere at least, you'll note
> that when the DI goes through 090 or 270, the compass stands a fair chance
> of agreeing with the DI. As you go through north, though, the compass will
> under-read, and as you go through south, it'll over-read. The only time you
> can rely on the compass is when going in a straight line - which is why you
> always check and adjust your DI when flying in a straight line.

Actually the compass is very predicatable in a standard rate turn and
its effect is well known and commonly taught to students as "compass
turns" as described in the FAA publication I posted earlier.

>
> Hence if you want to do a partial-panel turn in IMC, you fly straight and
> check the compass, then do a rate-one turn (the turn co-ordinator shows you
> the bank angle) for the required number of seconds - three degrees per
> second for a rate-one turn, of course.

You are describing "timed turns". That is a different technique than
"compass turns". Both are commonly taught to instrument students in the
U.S. and both result in very exact heading changes when understood.
Both are very difficult in turb though. ;)

-Robert, CFII

[Robert M. Gary]

Jim Macklin wrote:
> I'm speaking of the question by the OP, which seemed to be
> asking if all you had was the compass or the TC [needle],
> which would be primary.

In straigtht and level flight under partial panel the compass would
have to be primary because the TC cannot tell you if you are still on
the correct heading. Corrections would be made with the TC though. Just
like full panel when your DG is primary in straight flight. It is very
possible to roll out to a heading within 2 degrees in any direction
using "compass turns" technique.

-Robert, CFII

[Pixel Dent]

In article >,
"Gary Drescher" > wrote:
> "Jose" > wrote in message
> t...
> >
> > Nonetheless, it's what I would use as primary, if I only had that and the
> > whiskey compass.
>
> Yup. The crucial point is that the inclinometer tells you about slipping or
> skidding. So if it's centered, then the TC indeed tells you whether you're
> banked or level.
>
> --Gary

Just two weeks ago I had the wonderful experience of a real live vacuum
failure in the middle of clouds over a 200' ceiling. TC with
inclinometer to keep the wings level and GPS for navigation got me
safely down with help from ATC. I'd check the whiskey compass about once
a minute to make sure nothing was lying to me.

I always practice partial panel approaches without the GPS, but when it
happened in real life I was very happy to have it as a workload reducer.

[Jim Macklin]

I took the question to be either/or. What ever instrument
you are intending to keep at a constant, whether heading,
altitude or airspeed or RC, is your primary, but control
often is not done using that instrument.
If the choice was you have only one instrument that shows
any heading related indication, which would be primary
[compass or TC] then the compass must be primary, but the TC
would be "primary for control" and would get the scan
priority between what ever pitch instruments, the compass
might be scanned only 2% of the time with a majority of the
time on the TC/altimeter and a/s.

I further said that is all you had was the compass, then a
south heading would be best because it eliminates the
backwards turning error and magnifies the beginning of a
turn and in the correct direction...


"Robert M. Gary" > wrote in message
ups.com...
|
| Jim Macklin wrote:
| > I'm speaking of the question by the OP, which seemed to
be
| > asking if all you had was the compass or the TC
[needle],
| > which would be primary.
|
| In straigtht and level flight under partial panel the
compass would
| have to be primary because the TC cannot tell you if you
are still on
| the correct heading. Corrections would be made with the TC
though. Just
| like full panel when your DG is primary in straight
flight. It is very
| possible to roll out to a heading within 2 degrees in any
direction
| using "compass turns" technique.
|
| -Robert, CFII
|

[[email protected]]

On 25 Aug 2006 09:20:56 -0700, "Robert M. Gary" >
wrote:

>
>David Cartwright wrote:
>> "Greg" > wrote in message
>> ups.com...
>
>> The turn co-ordinator is your primary measure of bank, for a couple of
>> reasons. First, the compass doesn't measure bank angle - it just shows what
>> direction you're pointing in - whereas the TC does show the degree to which
>> you're banked. Second, and most importantly, because of the way it's put
>> together, the compass doesn't turn steadily, and so it'd be wrong to fool
>> yourself into thinking that the faster the compass was moving, the more
>> you're banked.
>

Most of you guys are far better qualified as I only have an IMC
rating. This is less demanding and only valid in the UK. Only 15 hours
training are required so to keep things simple I was told to use the
second VOR dial as a reminder of present heading by setting heading at
the top of the dial. When you make a turn you don't need any maths but
look where you need to be on the VOR dial and convert it visually to a
clock face. If for example you need to turn 120° right that's 20 past
on a clock therefore double and time 40 seconds.

Timing is simply bank into a rate one turn and visually add 40 seconds
to the clock hand (or could use a timer). The only calculation needed
is to double the interpreted time. Hopefully I'll only have to use it
when renewing the rating every couple of years.

As has already been mentioned the easier way is to use the ADF needle.

[Ronnie]

Greg,

From the Instrument Flying Handbook in the primary / supporting
method, the primary instrument is the one that provides a direct
indication of the parameter you are trying to control.

Therefore, compass would be considered the primary heading
instrument in partial panel for straight flight. If you are trying
to maintain a given heading, the compass is the primary instrument.

During a standard rate turn, you are trying to maintain the rate of
the turn. The turn coordiator or turn indicator becomes primary
during the turn.

From a practical point, the compass is difficult to interpret during
anything but straight and level flight. A ground track from a GPS
or Loran provides a good substitute for the DG during partial panel
situations. During partial panel, I tend to use the turn coordinator to
keep the wings level, ground track readout for heading info and timed
turns to make heading changes.

Ronnie



"Greg" > wrote in message
ups.com...
> In primary and supporting method of attitude instrument flying, which
> do you consider the primary instrument for bank in the partial panel
> situation (loss of both attitude indicator and heading indicator)?
> Turn coordinator or magnetic compass?
> thank you
> Greg
> greggordon.org/flying
>
>

[Gary Drescher]

"Ronnie" > wrote in message
et...
> Greg,
>
> From the Instrument Flying Handbook in the primary / supporting
> method, the primary instrument is the one that provides a direct
> indication of the parameter you are trying to control.
>
> Therefore, compass would be considered the primary heading
> instrument in partial panel for straight flight. If you are trying
> to maintain a given heading, the compass is the primary instrument.

Right, but Greg asked about the primary instrument for bank, not heading.

--Gary

> During a standard rate turn, you are trying to maintain the rate of
> the turn. The turn coordiator or turn indicator becomes primary
> during the turn.
>
> From a practical point, the compass is difficult to interpret during
> anything but straight and level flight. A ground track from a GPS
> or Loran provides a good substitute for the DG during partial panel
> situations. During partial panel, I tend to use the turn coordinator to
> keep the wings level, ground track readout for heading info and timed
> turns to make heading changes.
>
> Ronnie
>
>
>
> "Greg" > wrote in message
> ups.com...
>> In primary and supporting method of attitude instrument flying, which
>> do you consider the primary instrument for bank in the partial panel
>> situation (loss of both attitude indicator and heading indicator)?
>> Turn coordinator or magnetic compass?
>> thank you
>> Greg
>> greggordon.org/flying
>>
>>
>
>

[Allan9]

Years ago a FSDO/GADO Inspector pulled that one on me on a instrument flight
check.
Al

">
> If you've got a good ADF you can tune in an AM broadcast station and
> that makes a dandy DG replacement. Pick a station that's far enough
> away that azimuth to the station is approximately constant but close
> enough that you get a good strong signal. Not that most planes have
> ADFs these days, and the ones that do exist tend to be pretty cruddy.
>
>