G'day Bob, Rich, everyone else,

I trust you all had a good Christmas break! If you're anything like me you're still holding on to the added weight gained from the over indulgence in all that amazing Christmas food!

I have a question regarding the calculation of the amount of flight time available for a certain flight.

On page 2.9 (Navigation Issue 4) you give an example of how to calculate the amount of daylight available, which seems pretty straight forward. However, question 8 of progress test 2 shows a different working.

During the example the steps are simply:
- Determine the BoD for Port Hedland (in UTC)
- Determine the EoD for Adelaide (in UTC)
- Subtract the BoD from the EoD.

However in question 8, it's added that you need to take into account the longitudinal difference between the departure and destination aerodromes. It's said that A and B have a longitudinal difference of 15 degrees which accounts for 1 hour of the sun's movement. That time is then subtracted from the EoD (because you're flying east and thus losing daylight).

In the example (and I guess in real life), Port Hedland and Adelaide are seperated by 20 degrees of longitude (rounded up). The flight is also travelling east.

My question is, howcome no allowance for the longitudinal differance was made in the example but was in the question?

Hope all is well!

Cheers,

Dan

Hi there,

I hear you about the christmas food!

Allowance was made for longitudinal difference in the example, straight out of AIP (arc to time conversion chart). I think the reason why it's much more simplified in the question 8 workings is because it assumes the two towns are on the exact same latitude. So all that really needs to be worked out is the difference of longitude.

Since you can easily take 131 from 146 and be left with 15, the question just seems to be checking understanding of the effect of, the suns movement over degrees of longitude, on time.

Cheers

The explanation given in that question is simply an alternative way of approaching the problem. It is, of course, quite valid to take both LMTs back to UTC. If you do that you will have to 'invent' a date to make sure you don't try to take EOD from BOD [wrong way around].

The fact that the two towns are on different latitudes makes no difference, if the times are in LMT, latitude has already been accounted for. The alternative method requires that you see that the difference in longitude is 15°, which is exactly one hour of time difference. By taking one hour off B's EOD in LMT you convert both times to the same LMT and therefore you can subtract them to get an accurate answer.

You could also add one hour to A's BOD in LMT and you would get the same result.

Bob

Thanks for that Ellzy and Bob!

I ended up getting a question just like it in the exam. Was no trouble at all thanks to the book! I passed with 88%, which is okay. I got a question wrong in calculating the minimum distance from A you could commence a continuous climb OCTA while staying under the the various CTA steps. That was a 2 marker which was annoying. I got another 2 marker wrong, though without my KDR in front of me I can't remember what it was about.

Anyway, thanks heaps for the support!! Now on AERODY =].

Cheers,

Dan

Congratulations Dan! I am really happy for you on this. Way to go and good luck with Aerodynamics. I found Aerody to be relatively easy compared to Nav.

I know how challenging it has been for me, will see if I can interpret the questions correctly during the exam!

Cheers, Brook =]

Aerody I'm finding a little bit easier to understand than some, but like always there are my weak points. I'm just hoping I'll be able to pull it all together on friday, which is when I have the exam!

Are you done all your exams now mate?

Thanks Dan,

No still slogging it out, after this (if I pass I will reward myself with HPL as a relaxing subject (hopefully should be a breeze compared to Nav), then its onto Air Law and Performance (I'll do the multimedia course here).

I'm just juggling things between actually flying, my career, my family, moving house, and moving my stuff from East back to West, as well as running my flying. In the process of simplying all of those things (except family, my eldest daughter is becoming a teenager!)

I have done Air Law more or less before when I did a US to Australian Conversion for PPL but did it as a PAOS exam, but I still have to sit the CPL air law exam. I did my Aussie BAK and Student Licence, but found the US Cessna Pilot Centre courses really organised specifically in relation to flying Cessna Planes, plus it gave me a US licence as well as an Australian one. This could be handy in the future, given many of the larger aircraft are N registered

I am enjoying the learning, Nav for me has been slow going! I'll be glad when its over!

Brook