ATPL flight planning question

[xxRED BARONxx]

Hi guys, I am about to burn AFTs notes on flight planning I have because I cant get my head around something, I dont know if my brain is that fried from studying all day or it is genuinely poorly explained... here lies my problem:

It has to do with calculating the EMZW for cruise fuel flows.

The formula is: EMZW = SZW - (zone distance x ?? kg/nm) /2

#?? kg/nm=SGR#

*The "??" is dependent on 3 things...

1) WEIGHT - AVERAGE weights (70-80 tonnes) = 10kg/nm
- HEAVY weights (ABOVE 80 tonnes) = 11kg/nm
- LIGHT weights (60-70 tonnes) = 9kg/nm

2) WIND - For 50kts headwind + 1kg/nm
- For 50 kts tailwind - 1 kg/nm

3) Altitude - If FL below 280 + 1kg/nm

SIMPLE ENOUGH RIGHT?

The book goes on to give an example:

EG: -The SZW is 72400kg
- distance 488nm
- FL310
- .80mach
- ISA temp
- 50kt HEADWIND

"The SZW figure to use would be 10 (9kg/nm because of the weight. A SZW of 72400kg and 488nm means that the average weight will probably be below 70t, plus 1kg/nm extra because of the headwind which brings the number back to 10kg/nm)"

I understand the wind and the FL bit but what I dont understand is how the "average" weight is accurately determined. There isnt much of an explanation about how it is actually calculated (even if it is just a rough estimate).

So my question is how is this "average" weight determined???

thanks in advance

[DraggieDriver]

Take the SZW and subtract half the approximate fuel for the zone. It's going to be in the ballpark of 5000 kg for the leg, isn't it? even if you use the lowest fuel flow possible (light weight, but with headwind you're looking at 4880 kg, so half that is still enough to take you just below 70,000 EMZW).

Having said that, I didn't use AFT, and Secombe made me do everything accurately (and it was easy enough to get through the exam in the time provided with very high marks).

[Cravenmorehead]

My advice, have a beer, a lie down and have a go in the morning. Oh and don't use social media sites to get answers on ATPL questions.
Does the course not have a help line?
Craven

[dabz]

Flight planning... Hardest exam ever.

The "10" you speak of is a guessdimation on what you think the fuel burn will be per nm in that given situation. Another name for this is the Specific Ground Range.

Nathan says a headwind of 50kts would increase your estimated SGR by 1 and a 50kt tailwind would reduce it by 1.

However this is dependent on the situation. If the distance was less than say 300 I'd just stick to 10.

All this is used for to to work out an estimated fuel flow.
Once you have your fuel flow for that leg, half it and subtract that from your gross weight to see if it matches your estimated fuel flow.
If it does then move on.

Flight planning is a headache even to study and the way CASA construct their exam is crazy! 4 hours of work required to be done within 3... Good luck!

[training wheels]

Why don't you email Nathan with this question? He usually responds quite quickly. I used to receive replies from him all hours of the day and night .. I don't think he ever sleeps ..

[morno]

Email Nathan, he'll provide assistance. After all, if you paid for the notes, then you've also paid for his expertise!

Your EMZW is as has been explained. You take the distance, multiply it by an estimated SGR (10,11,12 or even 13 when it comes to doing DP's), then halve it. That'll be the mid zone fuel. Take that off your Start Zone Weight, and Bob's your uncle, you have your EMZW. Be sure though, to check your MZW to ensure it's the same as the Estimate! Otherwise your figures will be out and there's nothing worse than getting to the end of a 5 stage plan and finding your MZW at Leg 1 was incorrect.

Flight Planning is all about accuracy, combined with speed. So be accurate, but not to the entire detriment of speed.

If all of the above seems too hard and you're turning grey, take my advice; pick up the telephone, call AFT, book yourself onto the next flight planning course. 2 weeks well spent and you'll ace the exam if you pay attention........ And don't spend too much time at Scubar, :E

Would I sound nuts if I said I actually enjoyed flight planning? :}

morno

[MakeItHappenCaptain]

Email Nathan, he'll provide assistance. After all, if you paid for the notes, then you've also paid for his expertise!

LOL

What happened to the numbnut who was tryin to sell a set of notes on here??!?:E

[Checkboard]

Would I sound nuts if I said I actually enjoyed flight planning? :}

Sounds like you should get a job flying Pelair's Westwinds. :ok: