I have went through the complete fuel planning procedure a few times now, and once I managed to predict the winds aloft remotely well, (by flying the same weather and route twice :)) I can get to touch down pretty accurately with the planned landing fuel. However I have a few questions about fuel planning.1. Fuel gives you time in the air, which gives you distance, but... alas there is a catch. Fuel costs in weight. I can't find anywhere in the perf sheets or fuel planning procedures (maybe I didn't look hard enough), that accounts for the weight of the fuel on performance and recursively how that effects the fuel used. To explain by example...If I take off with MINs + a 1000 or so (say 5,000lbs) fuel to do a straight out, turn round and land and note the exact fuel used, then repeat with a MAX fuel load and again note the fuel used, I suspect there will be a fairly modest difference in that I had to cart all that fuel around, which inversely burns more fuel in the process. In planning this may become evident on shorter flights into heavily congested and weathered in airports, say JFK on a Friday evening, 5 o'clock, winter, dark and cold, with cloud and fog moving in and out of minimums for your class. So... you might take a couple of extra 1000lbs of fuel as you might expect to spend 30 minutes to an hour in hold, in the queue or go missed a few times.Say for illustration you are flying in from an airport only 200nm away and you take an extra 5,000lbs for hold and missed, also your alternate field, due to weather, is actually to return to where you lifted off from, so you will be landing at max landing weight.Surely your cruise fuel and possibly altitude will be different than if you were flying into an airport which was practically desserted on a straight in on ILS heading and a tail wind enroute. Your altern might be close and you land with only 5,000lb fuel, well below max landing weight.I think there could be 4,5,6000 maybe more extra weight in fuel between two flights of the same distance because of weather and traffic.My question is... How or where does one figure out the fuel/weght curve, or is the "IRL" difference, beyond whats in the fuel planning sheets minimal enough to ignore or allow it to move into the margin for error in the figures?**EDIT**I completely forgot the simple scenario. One flight with max PAX and bags, and the same route in plane positioning (ferry mode) completely empty, bar fuel. Surely the full plane will burn substanially more fuel than the ferry config one?**ENDEDIT**My second question is, roughly speaking, how much fuel do you burn once around a standard hold at 220kts?I was going to ask, how much fuel is used in a GOA, but that would depend on the airport proceedures, you might be able to just bring it round a pattern and make a quick visual approach from 5 miles out, or you might have to fly for 30 nm and make an ILS from 10nm out... you might even need to hold at low alt for a while. So for that I will use the "fuel used" value on the panel and experiement.Thanks for any info, insights :)

I just made a test flight just to see what I really did burn on the complete flight.Route:EGAA(25) - L10 FL330 - ASTRA1B - MAY - EGKK(26L)Weather:None.Configuration:BA 737-700MAX ZFW + Fuel = MTOW (133,000)Procedure:VNAV + LNAV at 1000 AGL runway heading (25), gear/flaps up on schedule, no holds enroute or on approach. APP hold on finals to rnw 26 EGKK. Full dual autoland, reversers to 90kts. Spoilers did NOT trigger, but I am having an issue with that and it's another story.Fuel burnt:3,040lbs.A go around at EGKK is climb ahead to the later of 3000ft or DME 10, then direct to MAY and hold. I slewed back to the runway threshold, tookoff and reset the fuel used guage. Flew the missed apprach, no hold at MAY, onto finals and full auto land.Fuel used:1,300lbsThere might be something wrong with those figures though, here's why.Fuel boarded: 13,000lbs.TO / Enroute / Approach / Land fuel: 3,000lbsMissed approach fuel: 1,300lbsRemaining: 8,700lbsThe take off to simulate missed, say generously: 500lbs.This means I "should" still have at least 8000lbs on board. I don't. I have 1600L, 1000C, 1600R = 4,200lbs. (Yes I had yellow fuel gauges on finals oops, thats me sacked!).I concur my plane has a leak, or the load master or fuel guy was having a larf!Next experiment is to take the same flight, with only 5,000lbs fuel and no cargo or people on board.

Check you used lbs throughout the process. In the Load Manager, in FS and in the PMDG Styles menu.