I am noticing a problem with the high altitude climb performance of the 737-800 and 737-900. For starters, I am using the load utility software to set the aircrafts payload and determine my zero fuel weight. After programming the FMS and taking off, the first thing I notice is that the TOC prediction on the ND is incorrect. The TOC prediction on the CLB page of the FMS is also incorrect. If I am climbing to FL350 the TOC prediction is always too close to the aircraft symbol on the ND and the aircraft usually levels off well after the point (although the point continues to remain slightly in front of the aircraft symbol). Furthermore, the aircraft is almost always unable to attain the FMS Optimum Altitude which is displayed in the cruise page.I am using an external weather program which is correctly setting outside air temperatures. On PROG page 2 of the FMS, I typically see temperatures around -40 above 30,000 ft which seems correct to me. I have verified that the zero fuel weight entered in the FMS matches the values in the fuel and payload window of the sim.Is this a known problem or is there something I can do to correct this issue? Thanks in advance for any replys.Alecs BainsCYYZ

Alecs,The TOC being very conservative is a known issue.Cheers,

This may also be attributed to the new -800/-900 FMC software upgrade. The -600/-700 FMC's economy climb used to be 283/.78 vs. the 284/.79 climb in -800/-900 FMC upgrade. The higher climb speed results in a lower V/S (usually around 500-800 FPM). It seems that FMC is calculating a TOC based on (possibly) a .78/1500 FPM climb. I tested this theory by limiting the FMC to a Mach .78 climb, resulting in approx 1200-1500 FPM and put me approx. 5 NM past the calculated TOC.Just my 2-cents..../R,Hawk

If that other weather program was Activesky 2004, then it may be worthwile getting the latest patch, which aparently fixed this - other people were talking about this in their forum not long ago.Geoffrey BaleanCanberra, AU (YSCB)http://www.hifisim.com/images/as2004proudsupporter.jpg http://www.vozvirtual.org/images/pmdgforumsignature.png"Today is the tomorrow you worried about yesterday. All is well!"Pentium 4 2.4GHZ, P4G8X Deluxe with Broadcom NetXtreme Gigabit Ethernet, 512MB RAM, LG Flatron L1710S 17" LCD, GeForce MX440 Millenium Silver, Creative Soundblaster Audigy, Logitech Speakers, CH Yoke & Rudder, Quantum Fireballp AS30.0 - Basically nothing crash hot :)MSFS 2004 acof, PMDG 737 6/7/8/900, Activesky 2004, Flight One Cessna 152, SquawkBox 2.3 w/ guage, ServInfo 2.2, FS AutoStart, FS Real Time, FSUIPC 3.212 (unreg.:()