ATC Endurance question

[WX Man]

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.

[High Wing Drifter]

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!

[Send Clowns]

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

[High Wing Drifter]

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

[RichardH]

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 !!

[High Wing Drifter]

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

[Send Clowns]

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.

[Alex Whittingham]

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)

[RichardH]

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.

[High Wing Drifter]

Still would not take HWD's technique of remembering answers

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.