Hi Guys,

Can somebody please help me with these three questions:

1- CAO 20.7.4.4.1.(a) says that any slope below 1% for take off can be ignored , however for example a 6% down slope or even a 1% up slope still can change lead to a completely different answer in the exam!!
for example Bob's example in the book (Page 3.22 LEONGATHA)uses no slope since it is 7% down and it is less than 1% up however if we use 6% down witch is allowed on the chart then we can take off with 2950kg instead of 2670kg , finally if we shouldn't use any slope lower than 1%, why the whole range of slopes are there on the chart?

2- are we allowed to use any slope on landing charts?

3- I understand that we shouldn't use wind for landing if it is given as a TAF of TTF, what would happen if we have just simply given the wing with no any other information to find out where this wind is dragged from?Are the exam questions always telling us that the wind is from TAF or somewhere else like ATIS?

Gday,

20.7.4.4.1(a) means any slope below 1% (on the upslope or downslope), such as 0.1-0.9% can be ignored. Anything more than 1% must be factored in. Easiest way to think of slopes being legal or not is to look on the takeoff chart and see that you can only use what has been included on the chart.



For example the Echo takeoff charts allow up to a 2% upslope and up to a 6% downslope. 2% upslope line is dashed to tell us not to attempt a takeoff at slopes greater than this. 6% downslope line is solid to say you can takeoff with say a 6%+ downslope but we won't give you any performance figures for it. The Leongatha example uses a .7% downslope thus can be ignored.

For the Echo, you can use any slope PROVIDED they are depicted on the chart. You may interpolate (use a 2.5% downslope) to get figures but you may not extrapolate (use a 2.5% upslope).

The exam will expressly state what the winds are that you should use for that particular question in order to find a takeoff or landing distance figure.

Hope that helps even a little bit!

Cheers

Thanks for your reply captainellzy,

Maybe I should change my question here, basically the question here is difference between CAN and MUST!
When we say slopes CAN be ignored it means I have a choice and this choice effects my final figures.
Let's look at this(Page 3.22 LEONGATHA)example, isn't it better to use 6% down slope rather than completely ignoring it?
For the sake of exam, should I ignore or I shouldn't , you know it can cause a huge difference.

Cheers

You MUST use a 6% slope, because it's more than 1%

You can ignore a slope of less than 1%, on the flipside, you can also use it. It will make a difference, however I don't believe it will be the difference between getting a question right or wrong in the exam as the multi choice options aren't that close together.

Bottom line is, anything greater than 1% up or down MUST be taken into account. Less than that CAN be ignored

Cheers!

Thanks again, I will go ahead with what you said.

Cheers

This business of slope on 'P' charts really needs addressing by CASA. I agree that the wording in the CAO suggests that slope must be ignored if it is less than 1%. Now that is just plain stupid. Why on earth would you not allow for a .9% upslope if the chart is already configured to allow it? I have contacted CASA on this previously and I get the 'vibes' that they think there are a lot more important things to worry about - so I got no joy there.

Anyway here is what I tell classes and the results in CASA exams are quite good.

If an exam question relates to a take-off or landing with less than 1% slope, I would allow for it. However if you don't, I can't see how they could mark you incorrect.

Use the wind in a landing chart unless the purpose of the calculation is to establish a maximum take-off weight. That is, you are going to be landing weight limited on that flight.

However, if a question simply says "What is the maximum landing weight permitted under the following conditions?', then use the wind.

I'm afraid I can't give you an 'official' rule because it seems there is none. The obvious question is "If you shouldn't use the wind on a landing chart, what is it doing on the chart in the first place?"

Thanks alot Bob, This is the kind of an answer I was after.

Hello again Bob,

Please excuse my stupidity here, but there is still one more thing which I? don't understand
in Page 3.22 LEONGATHA example, what would happen if we allow for 6% down slope? off course that 7% down slope is not on the chart, but isn't is better to use 6% down rather than nothing? is there any rule for this? or may be there is something here that I miss all the time.

Cheers

Actually the slope is 0.7% down to the south - not 7.0%. That's a common error students make. Also remember the Echo has a 5kt tailwind limit. So you cannot take-off or land in more than 5kt of tailwind.

Shahmirous,

A slope greater than 1% MUST be taken into account. Whether it is up or down. I agree with what Bob said earlier about if a slope is 0.9%, make it 1%, that makes practical sense. In the exam however maybe work it out with a 1% and no slope and choose the answer accordingly.

Good luck