Hi,
This could also be in the BAK Q&A category but as my first topic, it's also an introduction.
I'm studying for BAK at Lilydale FS in Victoria, and have gone through the take-off and landing chart examples in the Bob Tait BAK book with no problems at all. But LFS uses piper TO and Landing charts - have some sample questions but no answer sheet, and a practice exam with answers but only two TO&L questions and I'm struggling with correct use of the piper charts in both cases. I seem to be making a basic error that I can't pinpoint. No problem calculating PH but I think I might be using the baselines incorrectly. Does anyone know of an online tutorial or video, here or elsewhere, on Piper charts?
Many thanks

Hi Rob,

It is the responsibility of your instructor to give you adequate instruction on the use of the performance charts for the aircraft examined in the BAK exam. PPL is another matter however, CASA uses the fictitious Alpha, Bravo and Charlie aircraft.

Having said that, I have a 20 year old copy of the Tomahawk Pilot's guide (from AFE) and looking at the P-Charts in the back of that, they seem to be just a simplified linear chart without allowances for slope and surface. You need to adjust for slope and surface using distance factors for take-off and landing which are listed in tables with the P-Charts e.g. factor take-off distance by 1.25 for short wet grass, factor take-off distance by 1.1 for 2% upslope etc

However, this book is 20 years old and may not reflect the P-Charts for your aircraft.

As far as the base (or reference?) lines are concerned, from the PH and temp intersection point, run straight across to the bold reference line. From there you follow the guide lines down for headwinds or the dotted lines up for tailwinds until it intersects the windspeed of the day. Once you have that, read across from the vertical scale to get your distance required. You then factor that distance using the defined constants to get the final answer.

Here's an example from the Take-off chart:

Notice in this example they factor the final answer by 1.33 to allow for things such as condition of the aircraft and the skills of the pilot. This may not be necessary for you since a 1.15 Take-off or Landing Distance factor may have already been included in the charts for your aircraft.

Your best bet would be to have a word with your instructor about it and also get them to run through some examples to see where the problem lies.

Cheers,

Rich

P.S. absolutely loved Lilydale when we were down there a couple of years ago. It would have to be one of the better spots to learn to fly mate!

G'day Rich

Thanks heaps! That's a huge help. I was making an amazingly silly error - going to slope or headwind line before the reference line. It's encouraging that I had the principles right but was just using the chart incorrectly so adjusting that I am now getting the answers right. Also checked with an instructor who helped me through a few examples.
I think the added safety factor is a good idea.

Yes it's great learning at Lilydale, landing on the grass strips and with the light traffic - and the Yarra Valley is not bad as a training area!

All the best
Rob

Hi Rob,

Glad you got it sorted. Going to the reference line first before making your adjustment is the common principle with the linear type charts (the type Piper seems to favour). Onwards and upwards

Cheers,

Rich

Hi Rich
Just a quick note on my previous post in which I am asking about the solution to yet another question on Piper take-off charts - I seem to get the other answers right most of the time but the question I included in my new post is one I just can't get.
I'll also ask one of the instructors at YLIL when I get down there again on the weekend.
Cheers
Rob