Instrument Flying

(1)

I Fi

These instrument lessons will be dictated by conditions on

the day. It is expected that the student be sent solo to practise

these manoeuvres in the training area on a

regular basis

between dual lessons, however they will need a saety pilot or

any simulated instrument ight. Please reer to your CFI.

(2)

(3)

Co

Compass Use

Introduction

Limited Panel

Unusual Attitudes

Night Flying

(4)

(5)

Instrument

Fl

yIng

Objective

T

o turn

accurately onto

and

maintain compass headings,

compensating or known errors

in the magnetic compass.

Copa u

The magnetic compass is the primary navigation

aid or most light aeroplanes.

It is the only instrument in most light aeroplanes

that indicates the correct heading. The directional

indicator (DI) or directional gyro (DG) is simply

gyro-stabilised and can be set to any heading.

To be o any value it must be manually aligned

with the magnetic compass on a regular basis.

In using the magnetic compass or navigation

purposes there are more considerations than

just the turning errors.

The magnetic compass displays several errors

in its use, most o which the DI eliminates. I or

any reason the DI becomes unusable, the pilot

will need to be able to turn onto and maintain a

compass heading.

The cause o compass errors is not as important

as how to compensate or those errors in ight.

A basic understanding o the causes o compass

errors is all that is required.

Considerations

Variation

The earth has a geo

The earth has a geo graphical (Tgraphical (True) North Polerue) North Pole and a geographical

and a geographical (T(True) South Pole.rue) South Pole.

A magnetic feld exists around the earth, produced A magnetic feld exists around the earth, produced by the equivalent o a very large bar magnet

by the equivalent o a very large bar magnet within the earth. This results in a Magnetic North within the earth. This results in a Magnetic North Pole and a Magnetic South Pole.

Pole and a Magnetic South Pole.

Figure 1

The magnetic poles are not in the same places as The magnetic poles are not in the same places as the true poles; however, currently they are close, the true poles; however, currently they are close, enabling us to use magnets to navigate around enabling us to use magnets to navigate around the world.

(6)

The angular dierence between true north and The angular dierence between true north and magnetic north at any point on the earth is called magnetic north at any point on the earth is called variation. This dierence is more relevant when variation. This dierence is more relevant when navigating as maps are drawn with reerence navigating as maps are drawn with reerence to true north, and the aircrat is navigated by to true north, and the aircrat is navigated by reerence to magnetic north. This will be covered reerence to magnetic north. This will be covered during uture navigation lessons.

during uture navigation lessons.

Deviation

When the bar magnet or magnetic compass is When the bar magnet or magnetic compass is acted upon by a magnetic feld other than the acted upon by a magnetic feld other than the earth’s, the magnet deviates. Most metal objects earth’s, the magnet deviates. Most metal objects or electrical felds produce a magnetic feld

or electrical felds produce a magnetic feld that will cause the compass to read incorrectly. that will cause the compass to read incorrectly. This eect is known as deviation. It is

This eect is known as deviation. It is compensated or by the ‘compass swing’ compensated or by the ‘compass swing’ procedure, which minimises the errors and procedure, which minimises the errors and records the residual errors.

records the residual errors.

Dip

At the magnetic

At the magnetic equator, the earth’s magneticequator, the earth’s magnetic feld lies parallel with the earth’s surace, and a bar feld lies parallel with the earth’s surace, and a bar magnet would also lie parallel. As the poles are magnet would also lie parallel. As the poles are approached, the lines o ux dip down toward the approached, the lines o ux dip down toward the earth’s surace, and so does a bar magnet.

earth’s surace, and so does a bar magnet. Suspending the compass card rom a pivot point Suspending the compass card rom a pivot point above the magnet almost eliminates dip.

above the magnet almost eliminates dip. The pivot arrangement is unstable, so the The pivot arrangement is unstable, so the compass card and magnets are immersed in compass card and magnets are immersed in a uid that damps out oscillations, which a uid that damps out oscillations, which also provides lubrication.

also provides lubrication.

Figure 2

Acceleration Errors

The compass always sits at a slight angle to the The compass always sits at a slight angle to the earth because the magnet is suspended below earth because the magnet is suspended below a pivot point. The centre o gravity o the magnet a pivot point. The centre o gravity o the magnet will not lie directly beneath the pivot point, and will not lie directly beneath the pivot point, and when the aeroplane accelerates or decelerates when the aeroplane accelerates or decelerates the centre o gravity lags behind and rotates the the centre o gravity lags behind and rotates the compass card.

compass card. This does

This does not happen when heading north ornot happen when heading north or south

south, and is at a, and is at a maximum when heading eastmaximum when heading east or west

or west..

In practise, the compass will indicate an apparent In practise, the compass will indicate an apparent turn toward the

turn toward the SSouth whenouth when AAcceleratingccelerating and an apparent turn toward the

and an apparent turn toward the NNorth whenorth when D

Decelerating. The mnemonicecelerating. The mnemonic SANDSAND is used tois used to remember these eects.

remember these eects.

Although power changes, in aeroplanes with

sufcient power, may produce acceleration

or deceleration errors, these errors are most

noticeable during attitude changes.

T

Turning Errors

urning Errors

In a balanced turn the bar magnet stays aligned In a balanced turn the bar magnet stays aligned with the aeroplane and thereore increases its with the aeroplane and thereore increases its angle to the horizon.

angle to the horizon.

To compensate or this, when turning onto To compensate or this, when turning onto northerly headings the pilot must continue the northerly headings the pilot must continue the turn past the indicated heading, and when turning turn past the indicated heading, and when turning onto southerly headings, stop the turn beore onto southerly headings, stop the turn beore the desired compass heading.

the desired compass heading. The mnemonic

The mnemonic ONUSONUS is used to remember this;is used to remember this;

•

• OOverturn the required heading when turningverturn the required heading when turning

onto

onto NNortherly headings andortherly headings and

•

• UUnderturn the required heading when turningnderturn the required heading when turning

onto

onto SSoutherly headings.outherly headings.

The compass turn is carried out at Rate One – this The compass turn is carried out at Rate One – this is a turn o 360 degrees in two minutes.

is a turn o 360 degrees in two minutes. While turning at Rate One, the error between While turning at Rate One, the error between the desired heading and the indicated

the desired heading and the indicated heading on 000 and 180 is approximately heading on 000 and 180 is approximately 30 degrees. For this correction to work the 30 degrees. For this correction to work the turn must be Rate One, balanced, level and turn must be Rate One, balanced, level and without pitch changes.

(7)

I Fi:

Compass Use

3

3 Figure 3

Figure 3

The turn coordinator will indicate a balanced The turn coordinator will indicate a balanced

Rate One turn at normal cruise airspeed (it will not Rate One turn at normal cruise airspeed (it will not indicate the angle o bank).

indicate the angle o bank).

Airmanship

During taxiing the compass is checked or correct During taxiing the compass is checked or correct sense – turning right, numbers increasing,

sense – turning right, numbers increasing, turning let, numbers decreasing. On lining up, turning let, numbers decreasing. On lining up, the compass heading is compared with the the compass heading is compared with the

runway heading and can be expected to be within runway heading and can be expected to be within approximately 10 degrees.

approximately 10 degrees.

The turn coordinator should also be checked The turn coordinator should also be checked or serviceability. Most turn coordinators are or serviceability. Most turn coordinators are electrically driven and display a red warning ag electrically driven and display a red warning ag when power is not being supplied. During turns when power is not being supplied. During turns while taxiing, the turn coordinator should display while taxiing, the turn coordinator should display a rate o turn in the correct sense.

a rate o turn in the correct sense.

Emphasise that lookout is the most important Emphasise that lookout is the most important part o any turn and must be maintained, beore, part o any turn and must be maintained, beore, during and ater the turn.

during and ater the turn.

Aeroplane Management

The compass system should be checked or The compass system should be checked or serviceability beore ight.

serviceability beore ight.

I the uid in the compass has bubbles or leaks I the uid in the compass has bubbles or leaks out, the compass will become less stable. out, the compass will become less stable. Check or cracks or uid leaks as well as uid Check or cracks or uid leaks as well as uid discoloration.

discoloration.

Ensure the deviation card is valid by checking Ensure the deviation card is valid by checking that the expiry date has not passed. Although that the expiry date has not passed. Although the corrections given or various headings are the corrections given or various headings are generally considered insignifcant or practical generally considered insignifcant or practical ight use, the deviation card is the only indication ight use, the deviation card is the only indication that the compass swing has been done, and that that the compass swing has been done, and that any errors ound were not excessive.

any errors ound were not excessive.

The introduction o any metal object or electrical The introduction o any metal object or electrical feld, such as headphones, GPS or calculators, feld, such as headphones, GPS or calculators, into the cockpit will aect the accuracy o the into the cockpit will aect the accuracy o the magnetic compass. Keep these items as ar away magnetic compass. Keep these items as ar away rom the compass as possible.

rom the compass as possible.

As vacuum pump ailure is the most likely cause As vacuum pump ailure is the most likely cause o DI ailure, the suction gauge should be checked o DI ailure, the suction gauge should be checked during engine run-up (4.5 to 5.2 inches o Hg). during engine run-up (4.5 to 5.2 inches o Hg).

Human Factors

T

To minimise disorientation, o minimise disorientation, a three-dimensionala three-dimensional picture, including the cardinal points o the picture, including the cardinal points o the compass, should be developed and retained in compass, should be developed and retained in the pilot’s memory.

the pilot’s memory.

In-ight mental calculations should be kept to In-ight mental calculations should be kept to a minimum.

a minimum.

The pilot should not have access to unreliable The pilot should not have access to unreliable inormation that could be used. It is

inormation that could be used. It is

recommended that unreliable inormation, recommended that unreliable inormation, ie, instruments that have ailed, are covered. ie, instruments that have ailed, are covered.

Air Exercise

Draw the compass rose in p

Draw the compass rose in plan view, and dividelan view, and divide it into two halves with the cardinal headings it into two halves with the cardinal headings labelled. Turning errors are zero on east and west, labelled. Turning errors are zero on east and west, and a maximum o 30 degrees on north and south and a maximum o 30 degrees on north and south – label these.

– label these.

Intermediate headings and their associated error Intermediate headings and their associated error are now labelled. In addition, the top hal o the are now labelled. In addition, the top hal o the rose is labelled

rose is labelled ONON and the bottom haland the bottom hal USUS.. This inormation will need to be memorised This inormation will need to be memorised by the student and should be included in the by the student and should be included in the lesson handout.

lesson handout.

The procedure or turning onto a specifc compass The procedure or turning onto a specifc compass heading is broken down into several steps.

(8)

Making the Turn

Which Way to Turn?

The turn is always made in the shortest direction; The turn is always made in the shortest direction; or example, a turn rom east to north requires a or example, a turn rom east to north requires a turn to the let.

turn to the let.

Given the presentation o the compass rose, Given the presentation o the compass rose, this is quite a simple deduction. However, the this is quite a simple deduction. However, the aeroplane’s magnetic compass does not present aeroplane’s magnetic compass does not present the inormation in this ormat. Thereore, some the inormation in this ormat. Thereore, some method o deciding the shortest arc to turn method o deciding the shortest arc to turn through must be provided to the student. through must be provided to the student.

It is assumed that the DI has ailed or is unreliable It is assumed that the DI has ailed or is unreliable so should be removed rom the pilot’s scan.

so should be removed rom the pilot’s scan. As the simple plan view o the compass rose As the simple plan view o the compass rose is easy to interpret and is what the student has is easy to interpret and is what the student has memorised, some other instrument, preerably memorised, some other instrument, preerably orientated with north always at the top, is orientated with north always at the top, is substituted or the DI.

substituted or the DI.

There are several methods available. There are several methods available.

Firstly – and best – the back o the cover used to Firstly – and best – the back o the cover used to hide the DI could have a drawing printed on hide the DI could have a drawing printed on it that shows the error or correction associated it that shows the error or correction associated with each cardinal and intermediate heading. with each cardinal and intermediate heading. Secondly, i the aeroplane is ftted with an

Secondly, i the aeroplane is ftted with an ADF orADF or VOR, the remote indicators associated with these VOR, the remote indicators associated with these (ADF card or CDI) may be used as a reerence. (ADF card or CDI) may be used as a reerence. The frst step in visualising which way to turn, The frst step in visualising which way to turn, is to read the compass. This heading is plotted is to read the compass. This heading is plotted on the substitute.

on the substitute.

Then the desired heading is plotted in the Then the desired heading is plotted in the same manner and the shortest arc chosen; or same manner and the shortest arc chosen; or example, to turn rom 040 to 270 – which way example, to turn rom 040 to 270 – which way would you turn?

would you turn?

Figure 4

This method avoids mathematical calculations. This method avoids mathematical calculations. However, when the heading required is near the However, when the heading required is near the reciprocal o the current heading, it may result in reciprocal o the current heading, it may result in a turn the wrong

a turn the wrong way. In practical terms, i theway. In practical terms, i the desired heading is at or close to the reciprocal, a desired heading is at or close to the reciprocal, a turn in the wrong direction will have little impact. turn in the wrong direction will have little impact.

Will an Overturn or Underturn be

Required (ONUS)?

Without access to the error/correction drawing, Without access to the error/correction drawing, this would require the student to know,

this would require the student to know, or example, that 120 is a southerly heading. or example, that 120 is a southerly heading. In practice this can be deduced rom the In practice this can be deduced rom the methods above.

methods above.

What Correction Will Need to be Applied?

Unless a drawing on the back o the DI cover Unless a drawing on the back o the DI cover is supplied, the student needs to memorise the is supplied, the student needs to memorise the correction actors.

correction actors.

What Will the Compass Read When the

Rollout is Started?

There are three methods to determine this. There are three methods to determine this. Firstly, the heading on which to start the Firstly, the heading on which to start the roll- roll-out can be calculated mentally by adding or out can be calculated mentally by adding or subtracting the correct

subtracting the correction actor. Howeverion actor. However, this, this not only requires an appreciation o whether not only requires an appreciation o whether to underturn or overturn but also depends on to underturn or overturn but also depends on which way the turn is being made. For example, which way the turn is being made. For example, a turn onto north rom 090 requires an

a turn onto north rom 090 requires an overturn o 30 degrees to a roll-out heading overturn o 30 degrees to a roll-out heading o 330 (subtract 30), while a turn onto north o 330 (subtract 30), while a turn onto north rom 270 will result in a required roll-out heading rom 270 will result in a required roll-out heading o 030 (add 30).

o 030 (add 30).

The second method relies on the emphasis placed The second method relies on the emphasis placed on the meaning o overturn and underturn.

on the meaning o overturn and underturn. Overturn means go past the desired heading, Overturn means go past the desired heading, while underturn means stop short o it. In the while underturn means stop short o it. In the case o overturn, thereore, the turn is continued case o overturn, thereore, the turn is continued until the desired heading is seen under the lubber until the desired heading is seen under the lubber line and the turn continued or the appropriate line and the turn continued or the appropriate correction. In the case o underturn, when the correction. In the case o underturn, when the desired heading is seen approaching the lubber desired heading is seen approaching the lubber line the roll-out is started beore the desired line the roll-out is started beore the desired

(9)

I Fi:

Compass Use

5

heading is reached by the appropriate correction. heading is reached by the appropriate correction. A third method, more appropriate to CPL training A third method, more appropriate to CPL training than basic training, o estimating when to roll out than basic training, o estimating when to roll out relies on timing. Since a Rate One turn results in relies on timing. Since a Rate One turn results in a turn o 360 degrees in two minutes, the rate o a turn o 360 degrees in two minutes, the rate o turn is calculated as three degrees per second. turn is calculated as three degrees per second. Knowing the arc to be turned through, the amount Knowing the arc to be turned through, the amount o time required at Rate One can be calculated o time required at Rate One can be calculated and the turn timed using the clock.

and the turn timed using the clock.

When the calculated heading to roll out on is When the calculated heading to roll out on is seen under the lubber line, roll out smoothly. seen under the lubber line, roll out smoothly. Anticipation o the heading by 3 degrees, given Anticipation o the heading by 3 degrees, given the roll out takes about one second, should the roll out takes about one second, should allow or an accurate compass turn. Immediately allow or an accurate compass turn. Immediately choose a reerence point on the horizon and y choose a reerence point on the horizon and y on the reerence point, wings level, and balanced. on the reerence point, wings level, and balanced. Give the compass time to settle, do not chase Give the compass time to settle, do not chase the heading.

the heading.

When reading the compass, ensure that the When reading the compass, ensure that the wings are level and that the aeroplane is in steady wings are level and that the aeroplane is in steady balanced ight, as these are the only conditions balanced ight, as these are the only conditions under which the compass will read accurately. under which the compass will read accurately.

Making the

Making the Correction

Correction

Oten the required heading will not have been Oten the required heading will not have been achieved exactly, so minor corrections will need achieved exactly, so minor corrections will need to be made, using the 3 degrees per second to be made, using the 3 degrees per second Rate One turn principle.

Rate One turn principle.

Which Way to Turn?

Because o the way heading inormation is Because o the way heading inormation is presented by the magnetic compass it is vital presented by the magnetic compass it is vital to read the compass. The most common errors to read the compass. The most common errors involve simply turning toward the desired heading involve simply turning toward the desired heading or matching the position o the heading indicator or matching the position o the heading indicator on the DI with the lubber line’s position.

on the DI with the lubber line’s position.

One method is to reverse the sense. For example, One method is to reverse the sense. For example, i the required heading is let o the lubber line, i the required heading is let o the lubber line, turn right. This sounds simple but many students turn right. This sounds simple but many students fnd this method conusing.

fnd this method conusing.

Another is or the student to visualise themselves Another is or the student to visualise themselves in the centre o the compass rose and looking in the centre o the compass rose and looking down the compass heading over the nose o the down the compass heading over the nose o the aeroplane. I the compass reads, or example, aeroplane. I the compass reads, or example, 038 and the desired heading is 035, the desired 038 and the desired heading is 035, the desired heading is let o the present heading. Do not look heading is let o the present heading. Do not look at the compass.

at the compass.

Figure 5

Y

Yet another method et another method is to employ this to employ the serviceabilitye serviceability check carried out during taxiing, turning right, check carried out during taxiing, turning right, numbers increase, turning let, numbers numbers increase, turning let, numbers decrease. Thereore, a turn rom 038 to 035 decrease. Thereore, a turn rom 038 to 035 requires a decrease or let turn. This method requires a decrease or let turn. This method has the advantage that nothing new needs to has the advantage that nothing new needs to be learnt. But, this method works only or small be learnt. But, this method works only or small heading changes or corrections and cannot be heading changes or corrections and cannot be applied to the initial turn direction calculation; or applied to the initial turn direction calculation; or example, turning rom 030 to 300, the shortest example, turning rom 030 to 300, the shortest arc is let but numbers increase to the right. arc is let but numbers increase to the right. Where more than one method is available Where more than one method is available to explain a procedure or calculation, to explain a procedure or calculation,

it is recommended that you choose only one it is recommended that you choose only one explanation to deliver to the student. I the explanation to deliver to the student. I the student cannot understand that explanation, student cannot understand that explanation, rather than just repeat

rather than just repeat it a little louder, you canit a little louder, you can then use another explanation. Once the student then use another explanation. Once the student has grasped the principles, other methods o has grasped the principles, other methods o arriving at the same conclusion can be introduced arriving at the same conclusion can be introduced to reinorce learning.

to reinorce learning.

When to Roll Out?

There are two methods available to determine this. There are two methods available to determine this. The frst, used primarily in instrument ight, relies The frst, used primarily in instrument ight, relies on timing the turn at three degrees per second on timing the turn at three degrees per second and is reasonably easy to do or small corrections, and is reasonably easy to do or small corrections, 5 to 10 degrees = approximately two to three 5 to 10 degrees = approximately two to three seconds. Saying “one thousand” equates to about seconds. Saying “one thousand” equates to about one second, thereore, once the Rate One turn is one second, thereore, once the Rate One turn is started, counting rather than timing on the clock started, counting rather than timing on the clock is used.

is used.

The second, used in a practical VFR sense, is to The second, used in a practical VFR sense, is to estimate the required heading change and select a estimate the required heading change and select a new reerence point on the horizon, and complete new reerence point on the horizon, and complete a turn onto the new reerence.

(10)

In either case, roll out smoothly, maintain In either case, roll out smoothly, maintain

balanced level ight on the reerence point, and balanced level ight on the reerence point, and allow the compass time to settle.

allow the compass time to settle.

Airborne Sequence

On the Ground

During the preight inspection pay particular During the preight inspection pay particular attention to the serviceability checks o the attention to the serviceability checks o the compass and the validity o the deviation card. compass and the validity o the deviation card. Look at the compass heading beore turning Look at the compass heading beore turning the master switch on and the watch the eect the master switch on and the watch the eect o starting the engine.

o starting the engine.

During the taxiing instrument checks, note that During the taxiing instrument checks, note that the turn coordinator gives a rate o turn, not the the turn coordinator gives a rate o turn, not the angle o bank, and that the DI can be set to read angle o bank, and that the DI can be set to read any heading desired, regardless o the aeroplane’s any heading desired, regardless o the aeroplane’s actual heading.

actual heading.

The Exercise

The airborne sequence starts with a The airborne sequence starts with a

demonstration o acceleration/deceleration errors. demonstration o acceleration/deceleration errors. Maintaining a heading o 090 or 270 by reerence Maintaining a heading o 090 or 270 by reerence to the DI or reerence point, accelerate the

to the DI or reerence point, accelerate the aeroplane by smoothly pitching the nose down; aeroplane by smoothly pitching the nose down; note the apparent turn toward the south. This note the apparent turn toward the south. This exercise is repeated to demonstrate deceleration exercise is repeated to demonstrate deceleration eects by smoothly pitching the nose up; note eects by smoothly pitching the nose up; note the apparent turn toward the north.

the apparent turn toward the north.

Rapid movements o the throttle to produce this

eect (negating all previous engine handling

training) is neither required or

training) is neither required or relevant.relevant.

When this exercise is repeated on headings o When this exercise is repeated on headings o 000 or 180 no

000 or 180 no apparent turn will occur, althoughapparent turn will occur, although the compass may be seen to dip. Ensure the the compass may be seen to dip. Ensure the aeroplane is kept straight by reerence to the DI aeroplane is kept straight by reerence to the DI or reerence point.

or reerence point.

The demonstration o acceleration errors The demonstration o acceleration errors is concluded with a reminder, that when is concluded with a reminder, that when accelerating, decelerating or pitching, keep accelerating, decelerating or pitching, keep straight on the reerence point. In addition, to straight on the reerence point. In addition, to compensate or turning errors

compensate or turning errors accurately, it willaccurately, it will be necessary to avoid pitch changes during the be necessary to avoid pitch changes during the Rate One turn.

Rate One turn.

Turning errors are demonstrated by completing Turning errors are demonstrated by completing a 360 degree Rate One turn and noting the a 360 degree Rate One turn and noting the dierence between the compass heading and dierence between the compass heading and the DI on cardinal and intermediate headings. the DI on cardinal and intermediate headings. Point out that these errors or corrections are Point out that these errors or corrections are only true in a level, balanced, Rate One turn. only true in a level, balanced, Rate One turn. Start on a compass heading o 090 or 270 Start on a compass heading o 090 or 270 (with the DI aligned) and have the student read (with the DI aligned) and have the student read out the compass heading when you read out out the compass heading when you read out a DI heading. In a turn to the right you read a DI heading. In a turn to the right you read out 030 (DI), the student should read out about out 030 (DI), the student should read out about 010 compass, a 20-degree dierence.

010 compass, a 20-degree dierence. Once the errors have been observed, a DI Once the errors have been observed, a DI ailure is simulated. Using the recommended ailure is simulated. Using the recommended steps, compass turns onto cardinal headings steps, compass turns onto cardinal headings are practised.

are practised.

Beware o lookout degradation during calculations. Beware o lookout degradation during calculations. Commonly, when the aeroplane is rolled wings Commonly, when the aeroplane is rolled wings level, there is a tendency by the student to fxate level, there is a tendency by the student to fxate on the compass rather than maintain level ight on the compass rather than maintain level ight on a distant reerence point. This tendency can on a distant reerence point. This tendency can be overcome by covering the compass with your be overcome by covering the compass with your hand just as the student starts the roll-out and hand just as the student starts the roll-out and insisting that they choose and y a reerence insisting that they choose and y a reerence point. Allow the compass adequate time to settle, point. Allow the compass adequate time to settle, ensure the aeroplane is in balanced ight, and ensure the aeroplane is in balanced ight, and then remove your hand to read the compass. then remove your hand to read the compass. Depending on which method is used or minor Depending on which method is used or minor corrections, cover the compass again and corrections, cover the compass again and calculate which way to turn. Calculate the time calculate which way to turn. Calculate the time required or choose a new reerence, turn and required or choose a new reerence, turn and regain balanced level ight. Allow the compass to regain balanced level ight. Allow the compass to settle and remove your hand to read the compass. settle and remove your hand to read the compass. When the compass reads the correct heading, When the compass reads the correct heading, emphasise the reerence point to maintain emphasise the reerence point to maintain heading. Do not allow the student to fxate on heading. Do not allow the student to fxate on the compass – instruments are used to confrm the compass – instruments are used to confrm perormance, not set it.

perormance, not set it.

After Flight

The student will need to practise these solo. The student will need to practise these solo.

(11)

Instrument

Fl

yIng

Objectives

T

o experience

the sensory i

llusions

which occur when deprived o

visual reerences.

T

o maintain strai

ght and level

ight

by sole reerence

to the aeroplane’s

instruments.

T

o climb, descend

and turn by

sole reerence to

the aeroplane’s

instruments.

Iodcio

Flight in cloud can be dangerous because when

we are deprived o visual reerences, the body’s

other senses may provide conicting inormation

to the brain. Without the beneft o visual

reerences to resolve these conicts, loss o

aeroplane control can occur very quickly, usually

within a minute.

However, instrument ying has a practical

application to visual ying when the normal cues

are missing or misleading; or example, low ying,

mountain ying, night ying, or ying over water

with a poor horizon.

Instrument ight is challenging because o the

need to interpret and anticipate the instrument

readings while recognising or ignoring the

conicting messages sent to the brain by our

earthbound orientated senses.

Inadvertent ight into cloud can be avoided by

maintaining a high level o situational awareness.

However, a fve-hour course o instrument ying

is included in the requirements or PPL issue, to

give the pilot and passengers some chance o

survival should the event occur.

Considerations

Describe the method o simulation that you will Describe the method o simulation that you will use, or example, hood or glasses.

use, or example, hood or glasses.

Discuss the direct and indirect inormation that Discuss the direct and indirect inormation that each o the ight and engine instruments give, each o the ight and engine instruments give, as well as their power source.

as well as their power source.

The ormula Power + Attitude = Perormance The ormula Power + Attitude = Perormance remains unchanged or instrument ight. There are remains unchanged or instrument ight. There are two types o instruments; control instruments and two types o instruments; control instruments and perormance instruments.

perormance instruments.

Control Instruments

Attitude

Attitude Indicator or

Indicator or Artifcial Hori

Artifcial Horizon

zon

The Attitude Indicator (AI) or Artifcial Horizon The Attitude Indicator (AI) or Artifcial Horizon (AH) is the master instrument, because it (AH) is the master instrument, because it presents pitch and bank attitude inormation presents pitch and bank attitude inormation directly (in miniature) against an artifcial horizon. directly (in miniature) against an artifcial horizon. Miniaturisation o the outside world means Miniaturisation o the outside world means that small movements indicated on the attitude that small movements indicated on the attitude indicator represent quite noticeable changes in indicator represent quite noticeable changes in pitch and bank. Thereore, it is common to speak pitch and bank. Thereore, it is common to speak o pitch attitude changes in relation to the

o pitch attitude changes in relation to the

width o the wing bars representing the aeroplane width o the wing bars representing the aeroplane within the AI. For example, the straight and level within the AI. For example, the straight and level attitude is hal a wing bar width above the horizon. attitude is hal a wing bar width above the horizon.

(12)

Indirectly, the attitude indicator is a guide to Indirectly, the attitude indicator is a guide to airspeed (nose low – high or increasing airspeed, airspeed (nose low – high or increasing airspeed, nose high – low or decreasing airspeed).

nose high – low or decreasing airspeed).

The attitude indicator is most commonly driven The attitude indicator is most commonly driven by an engine-driven vacuum pump.

by an engine-driven vacuum pump.

Tachometer

The tachometer directly indicates the engine The tachometer directly indicates the engine rpm and indirectly the engine power output. rpm and indirectly the engine power output. In addition, rpm may indirectly indicate pitch In addition, rpm may indirectly indicate pitch attitude (rpm increasing – nose low, rpm attitude (rpm increasing – nose low, rpm decreasing – nose high).

decreasing – nose high).

The tachometer is commonly driven rom The tachometer is commonly driven rom the engine by a mechanical cable.

the engine by a mechanical cable.

Performance Instruments

Airspeed Indicat

Airspeed Indicator

or

This gives the aeroplane’s speed directly and, This gives the aeroplane’s speed directly and, indirectly, pitch attitude (airspeed increasing – indirectly, pitch attitude (airspeed increasing – nose low, airspeed decreasing – nose high). Its nose low, airspeed decreasing – nose high). Its source o inormation is the pitot-static system. source o inormation is the pitot-static system.

Altimeter

The altimeter directly indicates the height o The altimeter directly indicates the height o the aeroplane above a datum, usually sea level. the aeroplane above a datum, usually sea level. Indirectly, it indicates pitch attitude (altitude Indirectly, it indicates pitch attitude (altitude decreasing – nose low, altitude increasing – decreasing – nose low, altitude increasing – nose high). Its source o inormation is the nose high). Its source o inormation is the static system.

static system.

Heading Indicator

The heading indicator is known as the Directional The heading indicator is known as the Directional Indicator (DI), Directional Gyro (DG), or Horizontal Indicator (DI), Directional Gyro (DG), or Horizontal Situation Indicator (HSI). The DI directly indicates Situation Indicator (HSI). The DI directly indicates the aeroplane’s heading when aligned with the the aeroplane’s heading when aligned with the magnetic compass. Indirectly, it can indicate bank. magnetic compass. Indirectly, it can indicate bank. Heading indicators are commonly driven by the Heading indicators are commonly driven by the engine-driven vacuum pump.

engine-driven vacuum pump.

Turn Coordinator

The Turn Coordinator (TC),

The Turn Coordinator (TC), or Turn Indicator,or Turn Indicator, directly indicates the rate o change o direction. directly indicates the rate o change o direction. Indirectly, it can indicate limited angles o bank Indirectly, it can indicate limited angles o bank (provided balance is maintained), commonly up (provided balance is maintained), commonly up to about 35 degrees. Any urther increase in bank to about 35 degrees. Any urther increase in bank angle will not be indicated

angle will not be indicated by the turn coordinator.by the turn coordinator. T

Turn coordinators urn coordinators are normally electrically driven.are normally electrically driven.

Balance Indicator

This Balance Indicator is commonly incorporated This Balance Indicator is commonly incorporated within the turn coordinator and directly indicates within the turn coordinator and directly indicates balance. Indirectly, it indicates yaw i the wings balance. Indirectly, it indicates yaw i the wings are level, or bank. Its

are level, or bank. Its power source is gravity, orpower source is gravity, or the resultant o

the resultant o in-ight accelerations (CPFin-ight accelerations (CPF, CFF)., CFF).

Vertical Speed Indicator

The Vertical Speed Indicator (VSI) directly The Vertical Speed Indicator (VSI) directly indicates the rate o change

indicates the rate o change o altitude. Indirectly,o altitude. Indirectly, it indicates pitch attitude, and it is most useul it indicates pitch attitude, and it is most useul when used as a trend indicator, as it will indicate when used as a trend indicator, as it will indicate a tendency to change altitude long beore the a tendency to change altitude long beore the altimeter registers any change. Its inormation altimeter registers any change. Its inormation source is the static system.

source is the static system.

Instrument Layout

The our instruments, Attitude

The our instruments, Attitude IndicatorIndicator, Airspeed, Airspeed Indicator

Indicator, Altimeter, and , Altimeter, and Heading Indicator,Heading Indicator, are arranged on the instrument panel in a Basic are arranged on the instrument panel in a Basic T-shape.

T-shape.

The addition o the Turn Coordinator/Balance The addition o the Turn Coordinator/Balance Indicator

Indicator, and the , and the Vertical Speed Indicator makeVertical Speed Indicator make up the ull instrument ying panel.

up the ull instrument ying panel.

While not part o the six instruments reerred While not part o the six instruments reerred to the rpm gauge is incorporated into scan to the rpm gauge is incorporated into scan techniques as appropriate.

techniques as appropriate.

Instrument Lag

All instruments suer rom lag, some to a greater All instruments suer rom lag, some to a greater extent than others. All instruments, other than the extent than others. All instruments, other than the VSI, can be considered to be responsive enough VSI, can be considered to be responsive enough or light aeroplane use. The VSI, however, suers or light aeroplane use. The VSI, however, suers rom signifcant lag, and must be cross-reerenced rom signifcant lag, and must be cross-reerenced with other instruments to check its indications. with other instruments to check its indications.

Airmanship

The importance o checking instruments while The importance o checking instruments while taxiing, and in-ight

taxiing, and in-ight SADIESADIE checks are revised.checks are revised. During visual ight training the requirement to During visual ight training the requirement to counteract inertia (change – check – hold – adjust counteract inertia (change – check – hold – adjust – trim) will have become automatic as a

– trim) will have become automatic as a resultresult o cues detected by peripheral vision. These o cues detected by peripheral vision. These cues will no longer be available and the necessity cues will no longer be available and the necessity to consciously counteract inertia through this to consciously counteract inertia through this process when changing attitude will need to be process when changing attitude will need to be emphasised during early instrument lessons. emphasised during early instrument lessons.

(13)

I Fi:

Introduction

3

The student should be prompting the lookout, by The student should be prompting the lookout, by calling “clear let?” i a let turn is to be conducted calling “clear let?” i a let turn is to be conducted and should receive a “clear let” response rom and should receive a “clear let” response rom the instructor.

the instructor.

Aeroplane Management

The aeroplane’s vacuum and pitot-static systems The aeroplane’s vacuum and pitot-static systems should be described.

should be described.

The method o setting the attitude indicator’s The method o setting the attitude indicator’s aeroplane symbol beore ight, and the desirability aeroplane symbol beore ight, and the desirability o not altering it in ight, are explained.

o not altering it in ight, are explained.

Human Factors

Humans use three sensing systems to gather Humans use three sensing systems to gather and transmit inormation to the brain in order to and transmit inormation to the brain in order to remain orientated. These are the balance organs remain orientated. These are the balance organs within the vestibular system o the inner ear, within the vestibular system o the inner ear, the muscular pressure sensors o the nervous the muscular pressure sensors o the nervous system, and vision – the most powerul system system, and vision – the most powerul system o the three.

o the three.

The balance organs o the vestibular system The balance organs o the vestibular system sense angular acceleration or change o direction sense angular acceleration or change o direction in three dierent planes by the detection o uid in three dierent planes by the detection o uid movement in the semicircular canals. In addition, movement in the semicircular canals. In addition, the otolith organ senses linear acceleration as well the otolith organ senses linear acceleration as well as head or body tilt, through the movement o a as head or body tilt, through the movement o a jelly-like mass over sensitive hairs.

jelly-like mass over sensitive hairs. This system is limited by the inability

This system is limited by the inability to detectto detect change when the direction or the angular change when the direction or the angular

acceleration is constant or very slow. It can also acceleration is constant or very slow. It can also misrepresent acceleration as a nose pitch up, misrepresent acceleration as a nose pitch up, because o the eect o inertia.

because o the eect o inertia.

The muscular pressure sensors o the nervous The muscular pressure sensors o the nervous system are aected by gravity and allow us to system are aected by gravity and allow us to detect, or example, whether we are standing detect, or example, whether we are standing or sitting when our eyes are closed.

or sitting when our eyes are closed.

Crucially, this system cannot dierentiate between Crucially, this system cannot dierentiate between the various causes o increased G, or example, the various causes o increased G, or example, as the result o pulling out o a dive or o entering as the result o pulling out o a dive or o entering a steep turn.

a steep turn.

The visual system is the most powerul o the The visual system is the most powerul o the orientation systems and normally resolves any orientation systems and normally resolves any ambiguous or conicting inormation received by ambiguous or conicting inormation received by the brain, or example, this is a steep turn not a the brain, or example, this is a steep turn not a pull-out o a dive.

pull-out o a dive.

In instrument ight conditions the visual In instrument ight conditions the visual reerences used to resolve ambiguous or reerences used to resolve ambiguous or

conicting orientation inormation are not available. conicting orientation inormation are not available. Until considerable practise has been carried out Until considerable practise has been carried out to replace the normal visual cues with instrument to replace the normal visual cues with instrument readings, orientation conicts may occur, causing readings, orientation conicts may occur, causing various illusions, or example, the leans.

various illusions, or example, the leans.

Because the limitations o the human orientation Because the limitations o the human orientation system are considerable, and instrument ailure system are considerable, and instrument ailure is rare,

is rare, trust the instrumentstrust the instruments..

Air Exercise

The air exercise starts with a demonstration The air exercise starts with a demonstration o the limitations o the vestibular and

o the limitations o the vestibular and muscular systems.

muscular systems.

Selective Radial Scan

Selective radial scanning recognises that the Selective radial scanning recognises that the attitude indicator is the master instrument and attitude indicator is the master instrument and thereore employs an instrument scanning pattern thereore employs an instrument scanning pattern that radiates out rom, and always returns to, the that radiates out rom, and always returns to, the attitude indicator.

attitude indicator.

The relative importance o the perormance The relative importance o the perormance instruments varies – and thereore the scan rate instruments varies – and thereore the scan rate varies – with the manoeuvre being executed. varies – with the manoeuvre being executed. Describe this in relation to maintaining straight Describe this in relation to maintaining straight and level as well as achieving straight and level and level as well as achieving straight and level rom the climb and descent.

rom the climb and descent.

Airborne Sequence

The Exercise

It is important to demonstrate the limitations It is important to demonstrate the limitations o the body’s physiological orientation systems o the body’s physiological orientation systems careully. The instructions below should be careully. The instructions below should be

ollowed exactly so that the student experiences ollowed exactly so that the student experiences the alse sensations o turning and pitching. the alse sensations o turning and pitching. An unconvincing demonstration may lead the An unconvincing demonstration may lead the student to believe they are immune to alse student to believe they are immune to alse indications. There are many demonstrations that indications. There are many demonstrations that show the susceptibility o the human senses show the susceptibility o the human senses to disorientation; it should only be necessary to to disorientation; it should only be necessary to show a ew o them.

(14)

The False Sensation o Turning

In straight and level ight, ask the student to In straight and level ight, ask the student to close their eyes and lower their head, remind close their eyes and lower their head, remind them to resist any temptation to look out, i they them to resist any temptation to look out, i they do they will not eel what is normally sensed do they will not eel what is normally sensed during instrument ight.

during instrument ight.

Lower the right wing very gently and then Lower the right wing very gently and then positively roll the wings level while raising the positively roll the wings level while raising the nose attitude without changing power. At this nose attitude without changing power. At this stage ask the student what attitude the aeroplane stage ask the student what attitude the aeroplane is in. Their balance and postural sensations will is in. Their balance and postural sensations will normally lead them to conclude that the aeroplane normally lead them to conclude that the aeroplane has entered a turn to the let.

has entered a turn to the let.

The False Sensation o Climbing

In straight and level ight, ask the student to close In straight and level ight, ask the student to close their eyes and lower their head. Enter a medium their eyes and lower their head. Enter a medium turn to the let using a positive entry, then very turn to the let using a positive entry, then very gently change to a turn to the right while applying gently change to a turn to the right while applying consistent backpressure to the control column. consistent backpressure to the control column. Ask the student to tell you what attitude they think Ask the student to tell you what attitude they think the aeroplane is in. The sensation they have elt the aeroplane is in. The sensation they have elt will be that the aeroplane is in a climbing let turn. will be that the aeroplane is in a climbing let turn. Once the student has seen that the sensation Once the student has seen that the sensation received rom the senses o balance and posture received rom the senses o balance and posture can be misleading, they will have a better

can be misleading, they will have a better appreciation o the need to be able to y by appreciation o the need to be able to y by instrument reerence beore attempting to enter instrument reerence beore attempting to enter cloud or any other condition where outside visual cloud or any other condition where outside visual reerences are minimal or completely absent. reerences are minimal or completely absent. It is not necessary to handle the aeroplane It is not necessary to handle the aeroplane

violently or adopt extremes o attitude to achieve violently or adopt extremes o attitude to achieve the eects o disorientation.

the eects o disorientation.

During transitions rom the climb or descent During transitions rom the climb or descent to straight and level it will be necessary to to straight and level it will be necessary to slow the students actions down to consciously slow the students actions down to consciously ollow the change – check – hold – adjust – trim ollow the change – check – hold – adjust – trim sequence.

sequence.

Student Prac

Student Practise

tise

The student should have observed the The student should have observed the

instruments on previous VFR ights to veriy that instruments on previous VFR ights to veriy that small movements on the AI result in

small movements on the AI result in noticeablenoticeable changes in pitch and bank.

changes in pitch and bank.

Now have the student put on the hood or glasses, Now have the student put on the hood or glasses, get comortable and ensure they cannot see out. get comortable and ensure they cannot see out. Then they should practise the selective radial Then they should practise the selective radial scan, frst in straight and level, and then moving scan, frst in straight and level, and then moving on to climbs, descents and turns, emphasising the on to climbs, descents and turns, emphasising the change – check – hold – adjust – trim sequence. change – check – hold – adjust – trim sequence.

On the Ground

The handout or this lesson should include the The handout or this lesson should include the limitations o the human balance system, as well limitations o the human balance system, as well as a range o articles on incidents and accidents as a range o articles on incidents and accidents resulting rom attempting continued VFR ight resulting rom attempting continued VFR ight into deteriorating weat

(15)

Instrument

Fl

yIng

liid Pa

When any one or more o the basic six ight

instruments ails, or is unserviceable, the

instrument panel is limited.

Failure o the master instrument, the Attitude

Indicator (AI), is the most serious and, thereore,

the most commonly simulated.

the most commonly simulated. However, ailureHowever, ailure

o the other instruments does occur and it is

important to recognise the ailure early.

Limited-panel instrument ight at the PPL level

requires only the ability to y straight and level

and carry out level Rate One turns onto compass

headings (sufcient to reverse course and y out

o cloud). Additional briefngs will be required to

adequately cover the requirements o

limited-panel instrument ight or CPL students.

panel instrument ight or CPL students.

This exercise simulates the ailure o one or more

ight instruments, beore or ater inadvertently

entering cloud. In this situation indirect readings

o the other ight instruments are used to

fll in the gaps as a result o losing the direct

inormation rom the ailed instruments.

Limited-panel instrument ight still employs the

selective radial scan technique, which recognises

the changing importance o various instruments

with the phase o ight.

Objectives

T

o maintain strai

ght and level

ight by sole reerence to a

limited ight instrument panel.

T

o carry out Rat

e One level turns

onto compass headings.

Considerations

Various power or inormation source ailures, Various power or inormation source ailures, and their eects on the ight instruments, and their eects on the ight instruments, are discussed, rom the least serious to the are discussed, rom the least serious to the most serious.

most serious.

Although the tachometer is not a ight Although the tachometer is not a ight

instrument, its possible ailure should be briey instrument, its possible ailure should be briey discussed. Rpm can be estimated rom sound discussed. Rpm can be estimated rom sound and, since only the gauge is unserviceable, power and, since only the gauge is unserviceable, power is still available to be used as required.

is still available to be used as required.

T

Turn Coordinator (or T

urn Coordinator (or Turn Indicator)

urn Indicator)

T

Turn coordinators urn coordinators are normally electricallyare normally electrically

driven. I power is not being supplied to the turn driven. I power is not being supplied to the turn coordinator, a warning ag is displayed. Its ailure coordinator, a warning ag is displayed. Its ailure would mean that the rate o turn would have would mean that the rate o turn would have to be estimated using angle o bank (about to be estimated using angle o bank (about 15 degrees or Rate One, up to 100 knots). 15 degrees or Rate One, up to 100 knots). The balance indicator is unaected.

The balance indicator is unaected.

The turn coordinator is checked or serviceability The turn coordinator is checked or serviceability during taxiing and the electrical system during during taxiing and the electrical system during SADIE