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## CPL Nav question ROC

• Posts: 11

### swav created the topic: CPL Nav question ROC

Hi all
I got question about CPL Nav subject.
In one of the practice tests I have some problems how to calculate ROC

Given the following information:

Aerodrome ELV .......... 1250 ft
Cruise level ................. A075
Area QNH ................... 1023 HPA
Climb GS .................... 90 kt
Start of climb .............. 1000 ft AGL

Your calculation of the rate of climb required to reach cruise level 36 nm from the airport is -

could someone help with this question?
Thanks a lot
Swav

• Posts: 11

### swav replied the topic: CPL Nav question ROC

Hi Bob
After my calculation my answer was 247fpm and in the cyber exam said that it is incorrect.

The correct answer is between 210 fpm and 230 fpm.

And that's why I'm confused about the solution. I thought I need to deduct the pressure difference from 1023 - 1013 = 300ft, however not sure now.

Thanks

• Posts: 1961

### bobtait replied the topic: CPL Nav question ROC

Actually you must also allow for the fact that the climb starts at 1000 feet over the aerodrome. So the climb is from 2250 feet to 7500 feet = 5250 feet. You must climb through 5250 feet in the same time it takes to travel 36 nm at 90 kt = 24 min. 5250 feet in 24 minutes = 219 ft/min. The QNH of 1023 is not required in the calculation since both the elevation and the altitude are measured from sea level.