Cheers, Erin]]>

I have a better understanding of them now!! Thank you!!]]>

1. Heading change required

2. Heading required

I believe you'd agree they have a different meaning, where 1. would be the delta, 2. would be the number on a DG.

Hope this helps.]]>

MissSoph wrote: Can I ask… this will only work if you have that on track fix? Like you needed to divert around weather?

The principle is the same.

1. calculate drift (what winds have done to you). at this point in time you already know that you are off the track.

2. when you apply drift to your heading, it will bring you to the track

3. to intercept orginal track you need to correct more, otherwise you will end up abeam (parallel) to your destination

For weather avoidance in real life, read paragraph "Other applications" on page 112 Cpl Navigation book (ed. 2015). Basically use same angles (from your DG) and same times (using your watch).

Hope this helps]]>

First, a useful little mnemonic - which appears to date back to the quite early days of US military aviation - "iced tea is a pretty cool drink" to cover the order of things -

is a

gives the sequence IAS- position error - CAS - compressibility correction - EAS - density correction - TAS

The equation to correct EAS to TAS is shown below. As we are concerned with low performance aircraft, we will ignore EAS and use CAS in its place.

TAS = CAS/√σ

where sigma (σ) = density ratio = ρ/ρo

where ρ (rho) is the local density and ρo is the standard sea level density (1.225 kg/m

As an aside, when we play with performance stuff, we make considerable use of non-dimensionalised numbers (ratios, in this case). You may come across references to sigma (as above), delta (δ - ratio of pressures), and theta (Θ - ratio of temperatures) in your general aviation reading.

Now if we know CAS and sigma, for our low performance aircraft flying along at whatever height, then we can figure out the conversion from CAS to TAS. For low speed (ie non-compressible) flight, any of the navigation computers will do this for us.

Bosi, (that nice chap) has posted a scan of a Dalton (E6B) computer with this stuff shown, so we will use his scan for an example.

Now, if we were to look up a table of ISA values (you can get these from the net via Mr Google), we would find that the density at 10,000 ft is 0.7385 kg/m

Looking at Bosi's scan, the airspeed cutout is set to give a density height of 10,000 ft. This setting (known as a nomogram), while providing the density height for us, is not intended solely for that purpose. Its main purpose is to set the outer slide rule C/D scales to specific values.

If you look at the settings Bosi has ringed, at the position where the outside scale is "10" shows, on the inner scale, a value of 0.86. Notice that this is the value we worked out, above, for √σ = 0.8594, rounded off to two decimals for the slide rule precision.

Similarly, if you look at the position where the inner scale is "10", this shows, on the outer scale, 1.161. Again, notice that this is the value we worked out, above, for 1/√σ = 1.1637. The discrepancy simply reflects the fact that we can't read the third decimal all that accurately on the slide rule.

So, what the airspeed cutout is doing, is setting up the multiplications

TAS = CAS/√σ , and

CAS = TAS x √σ

depending on which way you want to do things - same result, though.

So, we can use the whizz wheel to get the value of sigma for any height and then multiple this by the standard sea level pressure to get the density at that height. You can use this to impress your colleagues at the Aero Club bar on a Saturday afternoon, should you so desire ....

Just a couple of clarifications, though, if I may -

Not quite. The pitot system is sealed so that there is no flow through it. What it is doing is bringing the incoming airflow to a standstill which results in an increase in pressure. The pitot gives us static + dynamic pressure. By using the static input from the static port, we can get rid of the static pressure component and end up with dynamic pressure, from which we can figure out speed.

Again, not quite. The driver in calibration is the altimeter, for which there are error limits. Once these are met, the end result is that the ASI errors will be small and, sometimes, zero. All aircraft will have a PEC card, including Cessnas and Pipers. Because the PEC is small for the ASI (except around the stall), we usually can approximate CAS to IAS without too much problem.

That is to say, corrected for pressure/temperature, or density.]]>

The only practical comment to emphasise, is that, as part of the intercept of the final, desired track, you

(a) apply a suitable amount of lead to commence the turn (so you don't fly through the outbound track), and then

(b) roll out onto the expected heading, and then, for a little while

(c) check that the expected heading actually provides the correct navigation solution and you end up tracking the desired outbound track.]]>

]]>

On the right side of diagram there are 3 text boxes:

- Altitude with arrow pointing down,

- Transition Layer (shaded in the middle),

- Level with arrow up.

The correct answer is prior to >Layer<.

Levels are fixed, whilst Layer vary depending on qnh.

The X cross tells when to change, however there is a keyword "prior" in upper right corner.

Hope this helps]]>

In my book that has been amended I'll check the errata

Cheers]]>

If you were at 2500 assuming flying West bound and Restricted area goes from SFC to 9000, I would assume you would want to climb to first even cruising level above RA. You can't fly at 10500 which is transition layer.

Depending on qnh (hopefully given) you would fly at fl125 or fl145.

I would also expect distance from Restricted area was given too.

enr 1.7-9

Nav workbook page 55 para. 14.1.2.]]>

John]]>

I’ve started nav… but my text book is a 2009 edition… and already I can see some differences…. Like the 10% variable … still referred to as 15%… should I purchases a newer edition… as all of my exercises are also going to be out .]]>

Nav workbook , ta appreciate the help brack down on this quarter deal .

Does this mean the reference of the flight is changing ? ]]>

It is not easy to offer comment as to how long is a bit of string if we can't see the bit of string.]]>

All of my calculations and answers excluding the first one which is correct, differ quite a lot from actual answers.

Am I the only one with this problem? or putting it as politely as possible is the whole book riddled with errors here and there?

Also answers that should be rounded up i.e 31.765 gallons are consistently rounded down to 31.7 instead of 31.8 & vice versa it goes on, and it's always conflicting due to these inconsistencies, which i find quite frustrating.]]>

- The Bob Tait Navigation Text Book and Navigation Workbook were perfect preparation for the exam! The 1:60’s in the book are so helpful! I did those about three times leading up to the exam!

- I highly recommend PPE for Vertical Nav questions as I had 2 identical haha! The questions in PPE for RoC and RoD are harder than what I came across on the actual exam! Bob Tait also very helpful!

- I only got four 1:60’s. Two of which required me to determine the Track Error, one asked for drift experienced and the other one was a heading change required. Only converging and diverging 1:60’s. No cross track for me!

- Fuel calculations were also relatively basic. The textbook has everything you need. I got asked 2 questions on endurance remaining and 1 on finding the fuel flow.

- The first two questions were finding HW and XW! Make sure to use your ERSA for X-Wind calculations to ensure that you have the correct value. I know some people who used their flight computer only and were off by 2-3 knots! They are box answers as well! A few heading and ground speed questions too!

- Note that there are many box answers in the Nav exam! So make sure you take your time with every question and try to be as accurate as possible!

- In terms of the theory side of the exam I would make sure that you’re all over the first few pages of the Nav book! The questions are quite difficult to break down as they are worded typical CASA style! But if you have a sound understanding of the form of the earth, true + magnetic direction, chart projections + scale, and can wrap your head around the questions in Nav Progress Test 1 then you’ll be fine! I had about eight 1 markers on this chapter

- I did not focus enough time on the first chapter and therefore was not up to standard for those questions in the exam. That’s where all my KDRs were! Lat and Longs!

- No GNSS questions whatsoever!

- My number 1 tip is to TAKE YOUR TIME! I worked from the top to bottom and went thru slowly but swiftly. I had around 30 minutes to go but didn’t submit my exam till there was 11 minutes left. I didn’t change any of my questions on fuel and vertical nav as I was sure they were correct the first time. But yeah, take your time! Good luck to those sitting in the future! You’ll all smash it!]]>

Bob]]>

That's a great result and thanks for the feedback it's always appreciated

Cheers]]>

(b) simple enough standard use of any of the navigation calculators (or, if you really want to be fancy, you can do it totally trigonometrically with the CR as you have the trig tables on the slides)

(c) you need to be just as competent in this one as any of the standard calculations.]]>

Hope this is helpful ]]>

(a) we are looking at a single leg. First assumption is to see if we can run the calculations with a constant wind.

(b) G/S = 117 kts. That's just too close to 120 kts to be coincidence (2 nm/min).

(c) planned interval to the first fix is made good. G/S matches plan.

(d) time expected at the next fix comes up 4 nm short of the fix so the wind has changed and G/S has reduced. Therefore, the time to get to the second fix will be a bit more than 2 min, ie we will be at least 2 min late at the second fix.

(e) distance to the destination is a bit less that from the first to second fix so, presuming that the wind change holds for the last calculation, we should be about 2+ mins (for the lost time from the first to the second fix) + 2+ mins (for the second fix to the destination) which is going to be, say, around 5 minutes late at the destination (give or take a bit).

The answer is going to be (d).]]>

I sat NAV CPL a year ago

I'm now doing my KDR, on obstacle clearance. Iv forgot the equation on how to calculate the clearance of a obstacle, from a certain distance from the threshold

Can you please screenshot one of your equations

Regards]]>

GS = 133 kts

ETA at destination = 0304

hindi.fullform.website/exams/upsc/ ]]>

Solid result and thanks for the feedback

Cheers]]>

I managed to source a loan for the exam, perhaps I will invest in a new one also.

Cheers]]>

Just a problem that, sometimes, folks make the exam type questions too complicated and it all turns upside down ...]]>

Here, here!]]>

I totally agree with you John, Bob and Stuart do a great job keeping up with the constant changes.

Thank you kindly.]]>

For M 030 060

Steer C 028 060

The compass heading is 2 under for 030 and is correct for 060. So halfway between it would be 1 under. Nobody is interested in fractions of degrees on a compass, so if the magnetic heading is closer to 030 than it is to halfway, use 2 under, if it is closer to half way than to either 030 or 060, use 1 under and if it is closer to 060 than halfway, make no allowance.]]>

Also, these days, the question usually requires you to type in an answer on the computer. In this case CASA has indicated that you should type in the nearest whole number (no decimal places). The marking scheme will allow a small margin of error in most cases.]]>

As the earth rotates, all places on the same latitude will experience the same duration of daylight.]]>

thanks for the fast reply.

I mean just for the tabulation to litres, 1 USG= 3.785L, do we need to multiply by specific gravity?

In the question above, the calculation is 57 USG = 1 USG/ 3.785L = 57 * 3.785 = 215.745L

thanks.

on a note. i have keep typing the wrong password for samdol1978 user account. My IP is 118.189.185.198. Please assist to whitelist.

Thanks]]>

Able to share what was frequently touch on for your paper?

BOD, EOD, PNR, fuel margin, TMG/HDG and FPT? Anything else amiss?]]>

I find the Workbook a little confusing - because are you meant to work through the Topics in the main book and then go to the Workbook?]]>

You are correct those answers are for a different questions strange that has never been pointed out before I'll amend the text to reflect that

Cheers]]>

The picture I attached shows my way to find the answer.

I can't find anything wrong with my method.

I think the main problem is that the TE which is 44 degree is not applied to 1 in 60 thumb of rule as normally the TE should be less than

30 degree.]]>

This part made it click:

(1) Referring to this question in Nav practice test 1:

Refer to the Bourke WAC.

You are on a flight from ST GEORGE (YSGE) (2803S 14836E) to WALGETT (YWLG) (3002S 14807E). You departed YSGE at 0308UTC. At 0324UTC you crossed the railway line (approximately35 nm SE YSGE) and fixed your position between Bonathorne railway station and NOONDOO township.

Using track error lines you estimate that the track error from YSGE to the 0324UTC position is 8 degrees right. You now alter HDG 16 degrees left to intercept the planned TR.

The aircraft should intercept the planned track at time ‐ Select one:

0335 UTC / 0355 UTC / 0340 UTC / 0330 UTC

The position refers to crossing the railway line 35nm SE of YSGE b/w Bonathorne and Noondoo township. However, this point is in fact SW of YSGE.

(2) As mentioned by an earlier post, some of the practice questions refer to the Bourke WAC, and many students may not have purchased this given it isn't a requirement for the exam. Would it be worth changing these questions to refer to routes on the Sydney WAC?]]>

Cheers.

Lucas.]]>

Did you end up finding out where to find the GAFs needed to travel across a few states?

Cheers.

Lucas.]]>

The longitude difference between Perth and Canberra is 34°. So Canberra is 34 ÷ 15 = 2.26 hours ahead of Perth. That's 2 hours 16 minutes (to the nearest minute).]]>

That is really up to you, the workbook is a exercise book as in lots of repetition of exercises to help make you proficient, The exam preps are different as it's trying to give you a feel of how the CASA exams are presented. The exam preps would be my suggestion along with the workbook

but it depends on how you confident you feel your knowledge of the subject is.

Cheers

Stuart]]>

(a) 60nm

(b) less than 60nm

(c) greater than 60nm

In that case the answer would be 'less than 60nm' because the meridians converge towards the pole, one degree of longitude is not a constant distance. The distance between meridians gets less and less as you move towards the pole.

Way back in the 70's when I did my SCPL NAV (now ATPL) the syllabus covered a topic on Departure - the distance between to points on the same parallel.

In short, the formula for departure (in nm) was relatively simple:

In the example above, the distance (departure) between Town A and Town B can be calculated as follows:

Dep = ChLon x Cos(Lat)

Dep = 60 Cos 30 = 51.9 nm

If the towns were on the equator the distance between them would be: 60 Cos 0 = 60 nm

If the towns were at 90S the distance between them would be: 60 Cos 90 = 0 nm (meridians converge at the pole)

Apart from the SCPL NAV exam I don't recall ever using departure to calculate the distance between two points!]]>

Very cogent point.

However,

(a) if one has a debimeter or similar, one is in front

(b) even an accurately known (ie generally dipped) pre-start quantity plus known consumption rates against the clock and the flight log, with a gross check against contents gauges ... will provide a reasonable starting point.

Much easier on big iron ..

Harold's story makes for riveting reading.

Another case I recall involved one of the airline's flight standards bosses in the left seat .. PER-MEL, as I recall .. didn't end up too promising at MEL .. eventually a very close unplanned diversion to CBR and the noises started stopping on the taxy in to the terminal.

A more recent 737 case involving two aircraft can be reviewed here - www.atsb.gov.au/publications/investigati...13/aair/ao-2013-100/ .

Historically, Australia is a right mongrel for unforecast fog, especially during the winter months. I have never been caught out to the degree of the cited stories but, on a number of occasions, we had sweaty palms running and re-running the fuel calculations in flight.]]>

I see where the issue is. You lose the half hour in the UTC to LST conversion. I got the same times as yourself give or take a minute with those AIP graphs.

Moral of the story. Remain in UTC time.

Thanks for your help Dav

Dobbo]]>

Thank you for your explanation, that is the answer i got, I must have read the question wrong somewhere...

Appreciate your help.

Cheers Dan.]]>

This is where I’m a little confused, I understand the first question which relates to the QNH being 1004 which makes cruising at 11,000 not allowed but when the QNH is more than 1013 (1028) wouldn’t the lowest fl available be 11,000?.... the transition attitude is always 10,000 so that’s 1,000 separation...]]>

AIP states 'The system of altimetry used in Australia makes use of a

transition layer between the Transition Altitude which is always

10,000FT and the Transition Level of FL110 to FL125 depending

on QNH (see Figure 1)'

My tired eyes read 'or' rather than 'to' between FL110 and FL125. Small text!]]>

Thinking back to the high school science classroom, the subject of measurement (fuel dip stick) and arithmetic based on those measurements may come to mind. More specifically, there are rules for determining the number of significant figures in quantities calculated from measured quantities like fuel.

Within the scope of this original post, say we dip the tank and get a reading of 85 USG - this is a measurement to 2 sig. figs. Now if we wish to convert to litres we can use any of the conversion factors (3.7854, 3.78, 3.79, 3.8) discussed earlier and get the same answer to 2 sig. figs.

85x3.7854 = 321.759 = 320 to 2 sig. fig.

85x3.78 = 321.3 = 320 to 2 sig fig

85x3.79 = 322.15 = 320 to 2 sig fig

85x3.8 = 323 = 320 to 2 sig. fig.

(Note that the red 0 in 320 is not significant. If it were the answer would be 320. with a decimal point after the 0)

In summary, we can use as

I don't know how CASA would deal with an answer like 320, but 320 lts is the mathematically correct conversion.

See Wikipedia for a more detailed discussion on significant figures

I have completely ignored the subject of the propagation of errors.]]>

Cheers

Stuart]]>

Well done mate - you should be very proud of that.

Bob]]>

Good luck next time round.]]>

Just commencing CPLH Nav and hit a snag early!! Questions 8 and 9 have me stumped with the answer explanations. Page 181.

Q8. ISA Temp at FL140 is -13, OAT is +7 so it's ISA +20.

Q9. 15000ft ISA +10 is a density height of 16200ft. Is this plus 10 degrees to get to -5 degrees?

If you wouldn't mind explaining that a little further for me that would be appreciated.

Thanks in advance.

Dobbo.]]>

You are asked to use a telephone to cancel your SARTIME when ever possible on 1800 814 931. Otherwise, you may cancel SARTIME by radio with the ATS unit responsible for your area - but certainly not the CTAF.

Read up on ENR 1.1 para 8.2.2 for details on cancelling SARTIME. Also AIP ENR 1.10 para 2.3.]]>

Bob]]>

The earliest departure time for a VFR flight from Sydney on August 18th is closest to -

Select one:

A: 172015 UTC

B: 172005 UTC

C: 172010 UTC

D: 172000 UTC

Using the charts in the AIP I found the answer which I believed to be 172002 UTC so I marked the answer as D. The correct answer was 172004 UTC which should have been B.

It's super hard to read the small charts and guesstimate approx half way between the latitude lines as it is. In the real world would the difference of 2 minutes really be that crucial? IMHO I'd always plan to arrive well before the recommended 10 mins prior to EOD.

Lettuce know your thoughts,

Bry]]>

Much appreciated!]]>

]]>

The questions that came out in the actual PEXO exam are generally familiar, but a good 30% of the questions required working out precise figures and entering the numbers, instead of the usual multiple choice questions.

Now on to HPL. Any tips anyone got for me for HPL? Are the questions (TEM included) in bob tait reflective of the questions asked in the actual PEXO exams?

Sidetracking, just interested to know if Bob will be retiring soon, and what's going to happen to the entire syllabus and business once Bob goes into retirement. I note that a certain Richard seems to be taking over some of the answering of questions in the forum, so wondering if he's the one going to update the syllabus in the future. Also, if Bob Tait can have ATPL materials, that'll be great! (planning for the future!)]]>

I am not aware of one and if there was, you would not be able to use it in the exam anyway. For study purposes you could quickly put a "legend study aid" together using cut-off legend sections of old charts and taping them together. There are a lot of common elements between the charts so it won't take you long to get your head around them.

Cheers,

Rich]]>

store.bobtait.com.au/cpl/ppl-cpl-navigation-workbook-book-only

Happy studying.

Bob]]>

Can you point out the operational significance of mild turbulence and sever turbulence in a weather forecast

I have difficulty in getting it from AIP]]>

and thanks for all your help!

Cheers ]]>

Blue skies and soft landings always...

Bob]]>

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