Please help!

I wonder if anyone can help me. I don't know where I am going wrong with my take-off and landing charts, but I managed to get all the related questions wrong in my last BAK exam. It is driving me nuts. I was so sure I was doing them right!

Here is an example I have.

find the minimun take-off distance required:
runway- 09/27
pressure height- 3000"
Temp- +20 deg
Wind- calm
slope- Level
Surface- Long wet grass
Weight- 950kg

(Please see my attached chart and let me know if you can see where I am going wrong) I really don't want to fail my exam again!!!!!!!!!!!
Let me know if you can't read it!

Hi Shannae,

The working looks OK to me although some of the lines might be slightly off (e.g. the intersection with the slope line). That might just be the photo though. What answer were you given for this problem?

If you got this one wrong, the things to look at are the exact positions of the lines and, believe it or not, one obvious mistake is using the wrong chart e.g. a Type 1 when the question wants you to use the Linear chart.

Just some general tips for these charts: be really careful with your lines - a couple of mm can make a significant difference if you somehow end up between two answer options. A cartridge pencil is excellent for this. They have a very fine tip that doesn't blunt with use.

Watch questions which give you a slope, runway directions and wind as discussed in this thread:

bobtait.com.au/forum/help-and-suggestions/2704-landing-charts

If you have any more examples post them here and we'll take a look.

Cheers,

Rich

P.S. Welcome aboard too Shannae! I'm glad you are getting a chance to fulfill a dream of flying. It's pretty good fun isn't it

Thanks for the reply Rich!

I don't have the correct answer unfortunately, as the chart I am using at home to practice is the one given in the supplement of the BAK book. (I do understand that the answer would vary depending on the chart used) I just really wanted to check that from the information given, I am plotting the graph correctly on the chart. I guess maybe I just need to take better care at my accuracy, even when I do use a cartridge pencil

Could you please give me examples of Type 1 and Linear charts? I'm not too sure which charts you mean by these sorry.

I have another example, sorry if the pic is not the greatest, and again I don't have the correct answer sorry, but like the previous example, I am just using the BAK supplement. Just making sure I am plotting the correct points from the info given in the question.

(a) is the first example I gave.

(b) is- finding the take-off weight if:
runway- 17/35
min take off distance- 720m
surface- short dry grass
slope- 1% down tot he north (since we would take off from runway 35, the slope WILL be down)
pressure height- 4000"
Temp- +30 deg
wind- 360/10kts. (Since wind direction is only 5 deg off the runway heading, the 10kts would be most, if not all, headwind correct?)



Once again thanks for your help Rich! And thanks for the welcome I am having a blast! So many days I sit at work and wish I was flying instead of sitting in an office all day, but gotta pay for it somehow right! Unless I win lotto tonight.. fingers crossed!!

Hi Shannae,

Yep, that one looks OK as well. By the way, mentioning cartridge pencils, chart types and line accuracy was me looking for ways you could possibly be going wrong considering that first example looked fine to me. Students have run into those kinds of problems in the past and yes, someone did use the wrong chart type and was tearing their hair out trying to see where they went wrong.

The other gotchas to remember with P-charts are:

- Watch problems with 5kt wind and a slope. Sometimes it is better to make use of the slope and accept a tailwind for take-off or landing. The only way to be sure is to work out taking off (or landing) in both directions and see which distance is shorter. In your second example, the wind was blowing at 10 kt which exceeded the maximum allowable tailwind of 5 kt for this aircraft. You have no choice but to take off into wind in this case.

- As far as CASA is concerned slopes of less than 1% should be ignored. In practice though, if the chart lets you plot for less than 1% slopes then why not use it? The answers in the CASA exam aren't normally that close though so whether you ignore it or not probably won't make much difference.

"Type 1" and "Linear Charts" are the two types of P-chart CASA wants you to know about. Type 1's are the type of take-off and landing charts you are already using in the BAK supplement. Linear charts are simply a different presentation favoured by Piper and you'll find them on pages 6 and 7 of the PPL supplement (you can download the PPL supplement here ).

Good luck with Lotto tonight

Cheers,

Rich

P.S. If you need another copy of the charts in the BAK supplement, you can download the PDF of any supplements here on the site. Here's the link: www.bobtait.com.au/books/supplements

Thanks for the tips Rich! I hope they help me in my next attempt at my BAK exam. Wish me luck!

Sadly I don't think I won the lottery Guess it's back to work again..

Cheers.
Shannae