Well due to being overworked I've left BAK until I'm almost ready for the RAA certificate flight test. Only need 0.7 more solo hours, have passed the radio (90%) and area solo (100%), ready for human factors and pretty up to date on most BAK stuff. But I just cannot work out BAK Practice Exam No 1 question 47P using the Piper take off chart!!

The question is:

Shade temp 30 deg C
Elevation 2000 ft
QNH 980hPa
Short dry grass
1% down to the east
Rwy 08/26 length 900m
Wind 240M/10kt

Q. MTOW is nearest to?
A 920kg B 960kg C 995kg D. 1055kg.

Answer sheet gives the answer as B. 960kg.

My calcs: PH = 2990 and headwind component = 9kt.
Take off rwy 26 into wind despite uphill slope?
Entering the chart at intersection of 30C ambient temp and PH of almost 3000, ruling across to surface reference line and adjusting upwards for 1% slope, then going across to wind ref line and adjusting down the curve to 9kt headwind, then across to TODA of 900m, I get right across the chart to the MTOW line for 1050kg. Too heavy according to the answer!!

What am I doing wrong???? I've tried this umpteen times. Please help! I need to pass BAK by Christmas for the sake of my sanity!

Thanks in anticipation...
Rob
PS finally getting some good weather down here...

Is there a climb weight limit?

Yep,
Good point, however using the intersection of 30 C and the 3000 ft PH line, gives a climb weight limit of 1000kg - still 40kg more than the answer sheet....
PS spent a few months in Broome many years back. Must be a great place to fly.

Hi Rob,

Can you tell me if this is one of our questions in the BAK textbook or online exams? I can't find it anywhere but I may have missed it. If it is a question from someone else, is there a chance you can get a copy of the P-chart to me so I can take a look for you - or is the same chart as can be found in our supplement?

Just one point though. Once you take the line across to the reference line for surface you need to go up to the line for short,dry grass before scooting across to the slope (at least that's how it is with the CASA P-chart). The surface reference line is for asphalt in the CASA chart, so you will need to adjust for the grass surface first before considering slope and wind. In the solution you described you went straight from the reference line to the adjustment for slope.

Could you upload a scan of your working and/or a scan of the chart you are using?

Cheers,

Rich

P.S. apologies for the delay in getting back to you - I've been packing up the sim here in Germany in preparation for the move back to Australia. So many boxes...

Hi Rich,
No worries at all. I should've mentioned that this question may not one of yours - it is from a photocopy given to me by one of the LFS instructors - possibly from a competitor's book. Oops I better signup for your practice exams instead!
Thanks for the note on going to reference line and then up to short dry grass. I did that, but my forgot to add to my post late last night. I'm at work now but I'll send a copy of the Piper T/o chart when I get home to see what you think.
Al the best with the move!
Cheers
Rob

Hi Rich

I am so sorry I forgot about updating you on this post. I went back and checked and although I thought I had gone up to the short dry grass line, sure enough I hadn't! So thanks for your response. I then got close enough to get the correct answer; despite minor variation due to trying to get the pencil to stay between the tiny gradations on the poor photocopy I had of the chart.

So anyway, I sat BAK and got 88% , would've cracked 90% except for a silly answer about who can certify you fit to fly after falling off a horse. (Yes that was the actual question! I incorrectly said my instructor assuming I'd have to first present a DAME certificate). Naturally have gone back to review all my weak areas.

After getting past human factors and getting the 5 solo hours done am just about to do the pre-test...finally!! It's getting interesting now.

Cheers
Rob

Well done on getting through the BAK exam Rob. Great job. Onwards and upwards!

Cheers,

Rich

Thanks Rich,

Just to let you know I passed RA-Aus certificate flight test on Australia Day. !!! Can't believe I actually got here.

Got a "Jab" booked for Saturday to build hours for passenger endorsement. Might just enjoy flying for practice and fun for a while before thinking what's next - nav in RA, or go for PPL.

Thanks for your help along the way. Every bit helps!

Rob

Hi Rob,

Congratulation on getting your wings! That is great news. now the fun and learning really start Have fun on Saturday and good luck with the endorsement. Keep in touch.

Cheers,

Rich

Hey many thanks Rich - will do.
Rob