Hello I was flying the NGX with Winglets at my FMC optimum cruise level of Fl375 and Mach .78 (FMC Speed) and was getting a fuel burn of around 1010 KG per engine per hour, does that sound about right, i read somewhere it would be around 880KG per engine per hour. I did look in FCOM but could not figure it out, thanks all

This fuel burn is correct. We normally use 2400kg/hr for quick fuel calculations.

thanks very much

How do you guys get the jet to that speed? I've had overspeed warnings at 300knots??

How do you guys get the jet to that speed? I've had overspeed warnings at 300knots??

Are you at your cruising altitude and have flaps/gear up?

You wouldnt fly at FL375 in real life - always whole FL levels. In general even levels westbound Odd levels Eastbound(there are some differences in parts of the world) With reference to 300kts overspeed it would depend upon your level - at FL370 you would overspeed at 300kts (IAS) TAS/IAS/MACH number and GS are all different things at different levels(excluding GS) at FL370 your speed is generally reffered to by MACH rather than IAS. Iit be unlikely to get above 280ias(and probably less) at FL370 in the cruise - but you could be at around mach .80 or around 470 TAS (these are rough figures and there are charts that help show and calculate correlation between speeds/temp/pressure/level)

Use the Table of Cruising Levels to help you choose an appropriate cruise level: http://upload.wikimedia.org/wikipedia/en/3/3e/Flgraphic.png

After approximatelly 26000ft use the change over on the MCP to swap the speed selection to mach. And from that altitude to above, use the mach limit istead of IAS one.