Nav question problem

[TwinOtterFan]

Hey all, I cannot figure out how to answer this question. Could someone help me? This will probably be really easy for you guys but seriously I have tried it about 5 times and cannot get it. I'm just at the point of pure frustration now.

The Question:

Question 8.jpg

So to me, if I take the altitude from the airport data 628' factor in the altimeter setting of 29.85 I get an additional 70' so a pressure altitude of 698' then its 18 degrees so that is 3 above 15 so 3x120 (the rule of thumb) is 360+698 = 1058?

Anyway I have accepted for tonight I am clearly to stupid to be a pilot, anyone that can help would be much appreciated.

required data

Data 1.jpg

Data 2.jpg

Airport Data.jpg

[CpnCrunch]

I've never heard of a rule of thumb for DA, and you won't need it for any written exams (as you'll have your e6b). But as for your error: it's not actually 3 degrees above standard at the airport...

[TwinOtterFan]

I've never heard of a rule of thumb for DA, and you won't need it for any written exams (as you'll have your e6b). But as for your error: it's not actually 3 degrees above standard at the airport...

I am clearly missing something here.... I used 15 as standard plus the 18 they put in that chart?

[CpnCrunch]

I am clearly missing something here.... I used 15 as standard plus the 18 they put in that chart?

No, 15 is wrong. Think about it.

[TwinOtterFan]

I wasn't decreasing the standard air by 2 degrees per 1000'...... but I'm still not getting 1200'

So 698' is about 1.396 degrees below 15. So 13.6 degrees.
Giving me 18 - 13.6 = 4.4 degrees.

4.4 x 120 = 528 + 698 = 1226'

[CpnCrunch]

I wasn't decreasing the standard air by 2 degrees per 1000'...... but I'm still not getting 1200'

So 698' is about 1.396 degrees below 15. So 13.6 degrees.
Giving me 18 - 13.6 = 4.4 degrees.

4.4 x 120 = 528 + 698 = 1226'

Yeah, so the answer is 1200. It's a rule of thumb, so it's not going to be exact. Just choose the closest answer.

[TwinOtterFan]

Thank you, I probably should have just taken a break but my day was shit, and my night sucked and I wanted at least one victory.

[TwinOtterFan]

One more question about this, when calculating the standard temperature do you use the altitude of the airport on the map or the altitude pressure altitude? So for this example the altitude was 628, but the pressure altitude was 698.