1achmed1 Posted June 29, 2015 Share Posted June 29, 2015 Firstly, I do know how to program the altitudes, that's not what I'm asking. My question is, how do I choose what to make the altitudes? If I'm flying KSFO - KLAS, via a SimRoutes route, when do I start to program the FMC for decent? I usually fly offline without ATC. Andrew P. S. Sorry about any grammatical mistakes, I'm travelling and I'm on my phone at the moment. Link to comment Share on other sites More sharing options...
MBKHOU Posted June 29, 2015 Share Posted June 29, 2015 The FMC will tell you the best altitudes, and also the TOC and TOD. I use simroute plans for offline ATC. And in that case, ATC decides your TOD. If you are in VNAV, you will get a yellow warning when you are getting close to TOD. Being I use ATC which decides when I will descend, when I get to that point, I turn off VNAV and go to MCP ALT and speed. I usually descend with vertical speed unless I'm not using ATC and am flying VNAV the whole way. But most of the time I'm using ATC. If you are flying with no ATC, you can just follow the VNAV path and TOD being you are deciding when to descend. The cruise altitude will depend on the distance to fly. Any flight over say 350+ miles, you can go to or near max cruise alt if you want, and I use whatever the FMC spits out. Shorter flights will use lower cruise altitudes.. IE: HOU to DAL "appx 250 miles" usually uses FL300 or so in the real SWA world. HOU to SAT, which I think is maybe 190?? or so miles, FL280. HOU to AUS which is even shorter, usually FL220. I've got to where I can guess pretty close on the usual cruise alt, and also the amount of fuel I need for a trip pretty much by sense of smell. I always verify using the FMC data though. Sometimes with a heavy load such as a long haul flight full of pax and fuel, you can't go to max cruise alt.. The FMC might suggest FL360 or so instead of FL380 or FL400.. Sometimes you can bump up a couple of thousand later after you burn off fuel. The FMC is constantly calculating the best optimum and max cruise altitudes, which generally increase a tad as you fly and slowly get lighter. The little 737-600 pseudo BBJ I run climbs like a scalded house cat, and being I'm usually pretty light in private BBJ config, I can usually go to max ceiling unless the route is really short. IE: I can run it from KHOU to KHOT, which is about 420 miles or so, and I go to the max FL410 every time. And it doesn't dawdle around getting up there either. :) But the majority of my artificial SWA flights, I don't get to go to max ceiling too often. Usually 37,38,39. But if I can use 40 or 41 on the semi rare occasion, I'll take it, as it usually saves a bit of fuel. Link to comment Share on other sites More sharing options...
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