ATC Endurance question
 

From the sample questions on http://www.jaa.nl/licensing/jar-fcl_questions.html: wondering if someone knows any better.

Finish the Endurance/Fuel Calculation and determine the ATC Endurance for a twin jet aeroplane, with the help of the table provided. Contingency is 5% of the planned trip fuel and fuel flow for extra fuel is 2400 kg/h.

Endurance/Fuel Calculation:
- - - - - - - - - - - - Fuel (kg) - - - Time (hh:mm)
Trip fuel - - - - - - - 5800 - - - - - - - 02:32
Contingency
Alternate
Final Reserve - - - 1800 - - - - - - - 00:42
- - - - - - - - - - - - - 1325

Min T/O fuel - - - -
Extra fuel - - - - -

Actual T/O fuel - - -
Taxi Fuel - - - - - - - 200

Ramp Fuel - - - - - 10000

We reckon that there is some sort of printing error, and that there is just no way of answering this question.

We has this very same, identical question in our FP exam!!

From memory:-

Shift the last two rows up one. The 1800 is Alternate with 00:42. The 1325 is Final, work out the endurance. You calculate the Contingency. The answer will be 4:07. If you see it, just answer 4:07!

If there is a printing error in the exam let your instructors know the exact question number, and the marks should be credited to you. That'll save a bit of time :D

I am afraid it was printed properly in the exam - in my case :( Just remember 4:07 :E

If you follow HWD advice don't be surprised to get the WRONG answer. This question or very SIMILAR has been asked for sometime now, BUT with DIFFERENT parameters. DO NOT remember 4:07 as this may well be WRONG.

Let THE expert guide you. I am alarmed that the number of students I get who have not been shown/remember how to sort this problem correctly. You need to apply JAA fuel policy rules.
So for some FREE advice :-

Table should look like this :-

---------------------Fuel---------Time
Trip----------------5800--------2:32
Cont 5%
Alternate-------- 1800--------0:42
Final Reserve----1325
Min T/O
Extra
Taxi-----------------200
Ramp------------10000

1. Calculate Contingency Fuel 290 kg
Calculate Contingency Time 152 min @ 5% = 08 mins

2. Calculate Min T/O = 9215
3. Calculate Extra 10000 - (9215 + 200) = 585 kg
4. RULE Final reserve for Jet A/C = 30 mins
5. Calculate Extra endurance = 585 kg @ 2400 kg/hr = 17 mins
NB. Extra does not include final reserve and may well be at a different burn rate in reality.
6. Taxi fuel is NOT included in endurance calculations

Your table should now look like this :-

---------------------Fuel---------Time
Trip----------------5800--------2:32
Cont 5%-----------290--------0:08
Alternate-------- 1800--------0:42
Final Reserve----1325--------0:30
Min T/O
Extra---------------585---------0:17
Taxi-----------------200
Ramp------------10000

Add up the times and get 4 hours 09 Mins being the ATC or Total Endurance as entered on ICAO Flight Plans.

This question needs to be tackled logically and NOT via guess work.

QED - Next time £30 ph but at least you might pass !!

Its a fair cop! 4:07 was the answe listed on the paper with the same parameters so beware.

Except the extra fuel only gives 15 minutes, not 17, Richard. At 2400 kg/hr 585 kg is burnt in 14.6 minutes, by my trusty CRP-5. That gives the answer 4:07, which is one of those offered where 4:09 is not. And we only charge £25 per hour ;)

Still would not take HWD's technique of remembering answers, except for a couple of specific questions that can only be answered by a specific technique that is completely useless for anything else.

Our Flight Planning expert agrees there's been a typo. We've shown what we think the table should look like and tagged the answers onto the specimen paper on this forum. Tom gets 4 hours 8.6 minutes, still going for answer (D)

15 mins not 17 mins for Extra = 4:07 Total.

I was wondering who'd be the first to spot that one!

Send Clowns have a house point.

ZOIKS! I didn't mean that seriously, I hoped the accompanying smilies would indicate that. Just in case, here's another :}

BTW, I now get 4:08 (FWIW). Can't quite manage 4:09.