VNAV Brutality!

[Guest JamesA]

Is it just me or does VNAV (737-700) produce brutal and unrealistic climb rates? For example, after completing a WOB2G departure from EGLL, I activate VNAV after the SID has been flown, and I get climb rates of up to 4000 fpm to begin with! Is such a rate of climb acceptable and normally used in real life? I also get descent rates of around 2100 fpm, is this normal?Thanks.James.

[Guest ba747heavy]

Perfectly normal, at least so far as I have been told.

[Mats_J]

As Fred already stated. Perfectly normal climb rates. To reduce climb rates if lightly loaded try to derate (TO-1/2, CLB-1/2) or use assumed temperaure thrust reduction (SEL TEMP). Apparently the latter is preffered as it's a 'soft' limitation on thrust.As I understand it the A/P in the real NG is pretty crude and not that passenger friendly. I've seen quite a few tips on ppRUNe about smoothly changing pitch attitudes with V/S and then use a more complex mode like LVL CH or VNAV once the major change has been done.Hope it helps,

[crvm]

There is no such thing as "normal" when it comes to VNAV. Everything is reletive to weight, power, weather and temperature and maybe a few other things. Try speeding up to your climb speed before you engage VNAV, it will transition to VNAV much more smoothly...Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/southparkcartmad.gif[h3]I WANT MY 747![/h3]Caution! Not a real pilot, but do play one on TV ;-)

[Guest JamesA]

Thanks to all that replied. I'll try it out now.

[Mats_J]

What Randy, Fred and I mean here is that there are ball park figures we can say contains normal values. Considering the above mentioned parameters. Right Randy? ;-)Cheers,