PPRuNe Forums - View Single Post - ATPL Flight Planning Tricks, Short Cuts etc
Old 17th Sep 2008, 14:49
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FRQ Charlie Bravo
 
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No worries mingalababya (what's your name mean? Am I being culturally insensitive by asking?).

I didn't get any CP questions on my exam (except for one really weird one where it was give but I had to plan Norm Ops to it and then OEI from it, basically just a straight forward plan but worded in such a way as to take a long long time to get my head around it... tossers).

So here's the wording of a question which I think would require Holding Fuel for DP ops except that the question directs you to just overfly it (Cairns to Alice overflying Mt Isa):

Mt Isa is forecast to be Suitable for the period of possible use if weather holding is carried to allow for INTERmittent deteriorations in cloud base and visibility due thunderstorms.
Another fun one (nowhere in the question is there any mention of the words Acceptable or Suitable with respect to the destination aerodrome, but it is a PNR so you actually don't go there anyway):

Hobart airport is experiencing TEMPOrary weather conditions during the period of possible use, which will at times be below the alternate minima, but not below the landing minima.
Wow, I forced myself to have an answer to all 5 point questions by 20 minutes on the timer today (individually, not as part of a practice exam). I averaged 22 minutes and got them all right, some small mistakes but only EMZW by a tonne which was damn close for fuel burn and even closer for PNRs. Like mingalababya I really feel the need to check and recheck so this was a good lesson. There is really no substitute for doing lots and lots of practice questions, it makes it easier to see the real story behind the numbers and methods.

On a technical note I realised today that in all of the PNR questions I examined; once I had a difference in flight fuels (my planned vs what I ought to have) I could just use generic SARs (Norm Ops 10 + 10 = 20, OEI 10 + 11 = 21, DP 10 + 13 = 23) in place of the actual SGRs and still get the right answers. Maybe I got lucky, perhaps it's not worth the time saved (about 1.5 minutes). Also realised that SGR can come from two sources (one of which can sometimes be teased from the question itself), SGR = Fuel Flow / GS or Zone Fuel / Zone NM.

One PNR question gave a BRW, a GW at TOC, then cruise reporting point 1, and cruise reporting point 2. My PNR guess was about 100 nm past the second reporting point so I just calculated the fuel burn between points one and two (difference in GWs given in question) divided by the nm to get an SGR and then applied that to the next 100 nm to my PNR. Sure I might have had a different EMZW if I'd done I the hard way but over 100 nm it was going to make bugger all difference. After that slick and easy calculation all I had to do was fly home from the guessed PNR at FL130. I had a hefty amount of fuel left to burn so after the correction I was off by about 13 nm from the correct answer (and about 140 nm from the nearest wrong answer).

By Jove I think he's got it!

Now one that's really pissing me off:

Pre-flight planning for One Inop PNR Cairns to Alice via Mt Isa. I've worked out a GW for the start of the OEI return to Cairns of 72,426, (the answer from the book comes to 72,450) so I round down to 72,000. It is ISA+3 so I round that to ISA+5 (and interploate). I plug this into the OEI Alt Capability chart and I come up with 25,440 feet or for a flight to the East FL250. Rob Avery chose FL230 (and burnt a lot more fuel).

I got the answer right (reference dist Mt Isa choices were 345, 270, 615, 180or 100) but I was still 15 nm off of his answer. Did I miss something? If you've done the AFT course and have seen the Rob Avery way of doing do you think that with his method he simply burnt a bit less fuel getting to the PNR (50 kg would do it) and round up to 73,000 kg for the table. Even old Rob seemed to have the same fuel flow as me but still went for the lower level (he doesn't give a GW just an SGR... that's his method I suppose).

Good night possoms.

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