So I'm going through the RPP/PPL sample exam provided by TC, and this question has me stumped. I'm pretty sure I'm doing everything right. The pressure altitude is 4000 ft, at 20 C the takeoff distance would be 2125. Now, the notes say to decrease that distance by 10% for every 9kts of headwind, and that would give you 1912 ft down from 2125 ft for your takeoff distance over 50 ft obstacle. But the answer key says the answer is (2), 2063 feet. Now for the life of me I can't figure out why this is. Any ideas?
Question:
http://i.imgur.com/3fHFx.png
Takeoff distances table:
http://i.imgur.com/WA7fg.jpg
Exam:
http://www.tc.gc.ca/media/documents/ca- ... 13014e.pdf
A question about the TC PPL sample exam
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Re: A question about the TC PPL sample exam
Keep reading.... 
Hint... What surface is the runway?
When you get to writing the exams, read the questions carefully! Ands ifs ors, etc make all the difference in some of the questions, turns into more of a language test sometimes, reminiscent of the LSAT.
Good luck!
Dan
Hint... What surface is the runway?
When you get to writing the exams, read the questions carefully! Ands ifs ors, etc make all the difference in some of the questions, turns into more of a language test sometimes, reminiscent of the LSAT.
Good luck!
Dan
Re: A question about the TC PPL sample exam
Right, I noticed the bit about the grass runway, but that says to reduce the ground roll... that's different from the total to clear the 50ft obstacle isn't it? If not, how would that factor in to it?
Re: A question about the TC PPL sample exam
A few issues here, no biggie. First off, did you mean to type "increase" ground roll instead of reduce in your reply? I'll assume so.
Anyhow, read the grass directive carefully...
"For operation on grass, increase distances by 15% of the ground roll figure.
You are completely right in that the ground roll is a separate figure, and also already included in the total distance, but you just take 15% of that ground roll number, and add it onto the total. Since the grass takes longer to accelerate on, you have to be able to account for that somehow!
Ground roll is 1115. Dont forget to correct that for headwind, (the chart says distanceS. 10% is 1004. 15% of that is 151.
Add that to the total takeoff distance that you already corrected for the headwind.
1912.50+151=2063
There ya go!
Anyhow, read the grass directive carefully...
"For operation on grass, increase distances by 15% of the ground roll figure.
You are completely right in that the ground roll is a separate figure, and also already included in the total distance, but you just take 15% of that ground roll number, and add it onto the total. Since the grass takes longer to accelerate on, you have to be able to account for that somehow!
Ground roll is 1115. Dont forget to correct that for headwind, (the chart says distanceS. 10% is 1004. 15% of that is 151.
Add that to the total takeoff distance that you already corrected for the headwind.
1912.50+151=2063
There ya go!
Last edited by DanWEC on Tue Jul 31, 2012 10:54 pm, edited 1 time in total.
Re: A question about the TC PPL sample exam
Oh, I see. That cleared it up. Thanks a bunch, great explanation.
