Another ISA question

[urdaddy]

I saw this question posted and I'm trying to solve it. An answer was provided. However, I don't see it! Please pass on some information if you can help out.

What is the altimeter error when 10,000 PH (never heard of PH either) at ISA -34?

At 10,000 ft standard temp is -5 (2c/1000 feet)
Difference of 29c
2% for every 5 degrees variation from ISA (approx 6)
6 x 2% = 12% (Over Reads)

Answer given is 14%

am I out to lunch or is there answer wrong? Also PH? Pressure height?

Thank you guys!
UD

[capt787]

ISA-34 = 34 degrees less than ISA temp. temp does not equal to -34 degrees C

-34 / 5 X 2 = -13.6%

true = indicate + temp error

true = 10000 + (-13.6% x 10000)

true = 8640 ft

[urdaddy]

Thanks 787!

Looks like I was out to lunch. I guess RTFQ!

Thank you for your post! Sorry for delayed response. Away for a while.

UD