600/700 VNAV Climb

[ernie274 0]

Since I got the 600/700 add on, I have noticed that during VNAV climb, the airplane starts an overspeed at around 30,000 feet. It just stays on 315 knots instead of switching to .80. I didn't have this problem with the base package. Am I doing something wrong? Also, I also find that the VNAV descent is a little more agressive than the 800/900. Is this normal?Thanks!

[pete_auau 1,152]

just flying the 700 now from ybbn to ybcs just climbed thru fl 300 ft and it changed to .79 so no problem here so far

[markadeane 272]

Hi Ernie (don't forget to sign your full name to posts )I certainly haven't encountered the climb issue. Are you using real weather? If so, what is the outside air temperature?Descent is quite different for each of the models, so provided everything is within limits, you're all good.

[afireinside1988 0]

I had the same issue sometimes with pre-sp1 base pack (HF4 installed). At FL300 the bird came into overspeed and didn't climb anymore. Had to reduce the speed manually at the CLB-Page in CDU, after that it worked fine. I use ASE for weather.

[markadeane 272]

Robin, every now and then ASE (a wonderful program, I might add) will inject an erroneous air temperature into FSX, usually WAY warmer than normal. This significantly affects a number of things in the NGX, and could also cause issues with the IAS/Mach changeover.If this happens to anyone, I suggest you first look at the air temperature figure on the upper EICAS screen. If it is much higher than normal, then that would be your prime suspect.Otherwise, I'd be looking at the CLB page and verifying that everything there looks as it should.As a side note, it's worth remembering that you should NEVER let VNAV or LNAV (or ANY automatics for that matter) take you someplace you didn't want to go in the first instance. If anything goes odd-shaped, don't hesitate to disengage the autopilot and put your handflying skills to the test to recover the situation.

[afireinside1988 0]

Hi Mark,thanks for the fast reply. Now, as you talk about air temperature, it comes into my mind, that often the temperature was really much warmer than reported from ASE. At the briefing page in ASE it reported temperatures between -50 to -60°C, but in FSX the upper DU reportet something around -25°C. I'm sure this would cause the problem but somewhere I've read, that ASE reports only OAT/SAT but the NGX shows TAT, could this be a reason for the differences?Is there any known fix or workaround for the wrong temperature injection from ASE?(Sorry for grammatically mistakes, my last english lessons was some years ago :))

[markadeane 272]

Robin, you'd have to take a look over at hifisim's forum for help on that.The issue has affected me only once, during early beta of the 737, and never since, so I'm not familiar with any fix for this.

[aentwis 61]

Refreshing the weather on the ASE interface often helps...Andrew

[pwafer 1]

Robin, the upper DU shows TAT, and as you say, ASE gives OAT/SAT. Have a look at the FMS CDU Progress page 2. It has SAT there and also how far off ISA.Ernie, certainly, as the lads state above, weather values injected into FSX can affect aircraft performance, but non changeover from IAS to MACH at FL300 sounds wrong. I would imagine changeover would occur well before that. Anybody got an explanation?

[aentwis 61]

I thought the change occurs around FL260?Andrew

[ernie274 0]

I am not using ASE. The only weather change I make at times is wind direction. I have incurred this problem with the changeover of IAS/Mach with both changing default wind direction and leaving it alone.Ernie

[ernie274 0]

I think I found my problem. I was using the ECON setting on climb. The default settings are 320/.803. While climbing, the Climb page shows ACT315 CLB with 315 on the PFD. The target speed from the ECON settings is still 320/.803. I think this difference is the problem. I reset the target speed before takeoff to 315/.802. I got the switch from IAS to MACH between FL280 and FL290 with no overspeed. I'm not sure why there is a difference when using ECON setting, but at least I know how to fix it.Thanks,Ernie