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PNR Questions Q6/Q8, page 4.51

  • Wong
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Wong created the topic: PNR Questions Q6/Q8, page 4.51

Hey guys!

This is my first post!:laugh:

I'm working through the PNR and ETP questions in Bob Tait's performance book. And ive come across Q6 and Q8. Ive completed both questions and my answers are slightly off, because ive also deducted the Startup and taxi allowance of 3US gallons in both questions. Answers explained dont have this value deducted.

So in Q6 i have a safe endurance of 227minutes and my distance to PNR is 300NM, whereas the answers are 233minutes and 307NM respectively.

In Q8, i have a calculated a safe endurance of 167minutes (64US gallons) and distance to PNR is 220NM, answers are 174minutes and 230NM respectively.

The difference in answers are quite small, just wondering whether i should be deducting the taxi/startup allowance or not?

Thanks!
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  • brentonrule
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brentonrule replied the topic: Re: PNR Questions Q6/Q8, page 4.51

Hi Wong. The difference (as you say) is in the taxi useage. When claculating PNR you do not have to include Taxi because the PNR is all about departing, going to a specific point, then returning to your departure point with all reserves in tact. Those reserves are only your Fixed and 15% Variable Reserve so you need not worry about the Taxi fuel for PNR calcs.

Hope this helps.
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Richard replied the topic: Re: PNR Questions Q6/Q8, page 4.51

Hi Wong,

In Q6 you are told you have 120 gallons of fuel at Take-off. Watch that one. In any question where you are asked something about fuel "at take-off", you ignore taxi and start-up allowances because you can assume they have already been burnt.

In Q8, you are in flight and have just had station passage at the NDB 103 nm from Alpha. You are doing calculations based on your fuel burnt in flight so far and the remaining useable fuel. Deducting a further 3 gallons for the taxi/startup allowance in this case is not required.

Just watch out: you may need to consider taxi/startup if the question asks for the distance to the PNR if you have X gallons "at startup", "on the ramp" or something similar. For the exam, it's all in the wording but fortunately it is also quite logical and reflects how you would calulate it in real life.

Cheers,

Rich
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  • Wong
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Wong replied the topic: Re: PNR Questions Q6/Q8, page 4.51

Thank you, brentonrule and Richard for clearing that up for me!

Just have to ensure in the exam i pay attention to the wording, before i start hammering away at the calculator! :laugh:

Now to tackle the weight and balance/loading chapter of performance.
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