hi all I was wondering if anyone else is experiencing what seems to be very high N1 speeds with the PIC/POSKY 767. i did a flight today adn when I reached my crz alt (33000) with VNAV and LNAN engaged the N1 reading was 94.4% at a weight of 255,000 is this not very high for such a light weight? also another issue is that when i select speed intervene and dialed in 280knts the engines stated oscillating up and down. i thought it may haver had something to do with the high speed winds aloft but really not sure what is causing this- does not happen when in VNAV.

The figures from the QRH (Airspeed Unreliable Checklist) show that at 35,000 feet at 120,000kg (close to your weight) 87% is required to maintain M0.78.The figures from the charts for 120T / F330 indicate that you should be achieving M0.83 or so.This all seems pretty good for a simulation!I have a few questions:What speed were you trying to achieve?What cost index is in the FMC?Are you sure the weight's accurate?Hope I can help!

You need to report other data like cruise speed and TAT. It's hard to say if 94% is high or low without this data.Don't know what to tell you about your oscillating speed. Sounds like possibly upper air turbulence (you can disable this in FSUIPC if it bothers you) or joystick noise on the throttle axis (also correctable with FSUIPC and utilities like CTFJ). If you disable the joystick and the oscillations stop, there is your culprit.J

my speed with VNAV was 306knts (.80 Mach) so it seems 94 % is pretty close. i will try disabling my joystick throtle axis as u mentioned and hopefully that solves trhe problems- thanx for the tips.

As others already have said you need to tell us more before anybody can give an educated answer, but to give you some indication I can tell you about a "problem" that I have encountered recently:Flying close to an airport in Sweden (ESNS) there seem to be some faults in that aiport's weather-reports used by FSMeteo that gives a TAT of about +40 degrees Celius (and an outside temperature of about -15 degrees) at FL330! This means that I need T/O power (about 107%) just to maintain speed until I reach an other reporting station.This is not a fault in PIC, quite the contrary, but a fault in a realistic temperature at that level (should be around minus 60 degrees).So if this happens again, look at TAT and outside temperature (as seen on page two in Route) and if these are not realistic you'll found the problem.Regards,G

I do think your readings are a little high for the data points you do report. Still, without TAT its impossible to say.The tables I have show that for a 763 at 360Klbs, 0.83M cruise (IAS:296 TAS:482) at FL330 with a TAT of -19C, the optimum N1 is 92%, with EPR 1.33, and a measured fuel flow of 13.1Klbs/Hr.This of course will vary with actual engine type, performance rating, actual measured TAT, weight, etc. Its important to note your actual IAS and TAS speeds as well...if you have warm air and a strong tail-wind, your engines will be working harder to maintain a constant speed.As Goran mentiones, if you use Real Weather like ActiveSky or FSMeteo, you can get some pretty squirrely numbers for TAT readings from time to time which will dramatically alter engine efficiency.

Note: a realistic OAT in the Northern Hemisphere at this time of year would be about -55 to -60 C. TAT usually runs about 23 or 24 degrees warmer than that.

Thanks Jase, forgot to say that. ;-)G

Just as a follow-up, I am in the midst of a flight as I write this. TAT is -25C, Cruise is 0.80M@FL330, GW is 332,000 and N1 88%.J

Later, I found myself at FL370 and M0.81, GW was 309,000 with a TAT of -31C and 126 knots of tailwind blowing up my pipe - N1 was 96%.As you can see...varied weights, TAT, wind speeds, cruise speeds, and altitude can all impact performance substantially.J