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View Full Version : Citation X - Climb and step climb performance


davys747
10th Sep 2013, 04:40
Hi all,

I am not a pilot, although I am an enthusiast and I am a controller. I was wondering if somebody might be able to shed some light on a few questions I have regarding the C750. My questions are based off my experience with Flight Sim (try not to hold that against me too much) and I'm sure most of the issues are caused by the sims inability to model correctly. Also bear in mind that I don't have an FMC for it so I have nothing to tell me optimum levels or when to step climb.

I found an old copy of the C750 Flight Planning Guide and I use that a lot. To start with I'd like to ask a question relating to this.

The table for a 300kt / M.80 climb at a starting weight of 36,100lbs shows the maximum level you can reach (in ISA conditions) is FL430. If you want to go higher, a step climb is required. However, the Cruise Tables for High Speed Cruise and M.82 Cruise indicate you can cruise at FL450 at a cruise weight 36,000lbs. The M.86 Cruise table indicates that at 36,000lbs, you can only cruise at FL410. To me this doesn't make much logical sense. Could anybody explain this?

Lets say I am doing a 2800nm flight that requires almost full fuel and the all up weight is around 35,500lbs. According to my tables, the only way to make that range is to eventually reach FL490. I know I can only go up FL430 so I would initially climb to that level. Once you are approaching FL430, is there sort of quick indication i.e. SAT or some other such thing, which would tell you that could infact climb higher? What would need to be considered before continuing the climb?

From the way I read the FPG, you climb at M.80 and then once you level off, you would increase speed to M.90 or so for high speed cruise? Is M.80 still good for the high FL400s?

Again, since I have no FMC, how do you judge the best time to step climb? What things need to be considered? Do you step at M.80 or at your cruise speed?

And whilst I am here, for the descent, all I have is "High Speed" and "Normal" with only rates of descent and no speed. So I have used M.80 into 300kts for High Speed. It seems to work well enough - is that realistic?

Appreciate your help.

Thanks.