Quick one on VNAV

[Ceri Hurlow 17]

Hi All,

 

Yesterday i was flying the LAM4M SID out of Gatwick and some of the initial legs are at 4000 or 5000 feet i believe to deconflict with heathrow traffic. However if i reset the altitude in the altitude window when flying the legs on LNAV/VNAV, the aircraft will climb to what i have set it to (I set 15000ft) rather than following the hard VNAV constraints, is this right. I would have thought it would have only happened if i set the altitude for those legs as 4000A for example rather than 4000.

 

Lately i also find that i need to disengage and reengage VNAV for it to follow the descent path before it does what it should. I am running SP1C and have reinstalled.

 

Hope someone can offer some advice

 

Thanks in advance

 

Ceri

[Fabo 213]

It definitely deletes the constraint if you do ALT INTV. I dont think it should do so if you simply turn the ALT up...

 

I am not sure what is exactly your problem on DES, try to be more specific.

[zubart 5]

First, the proper procedure would be to set each altitude restraint in the MCP altitude window to insure that altitudes aren't busted as you depart and not set it to 15,000 feet. Only set the MCP altitude window to the actual altitude ATC clears you to. This backs up the LEGs page altitude constraint. If ATC had cleared you to 15,000 feet, then you would have deleted all altitude constraints on the LEGs page below that.

The other obvious questions would be was VNAV engaged? Did you cross check the LEGs page to verify these altitude restraints are indeed on the LEGs page?

 

John Floyd

[Ceri Hurlow 17]

Thanks all, i definately did not delete the constraints and i'm fairly sure i was in VNAV, i'll try it again and have a closer look and get back

 

Thanks

 

Ceri

[Tabs 2,790]

If you have hard altitude restrictions set for the climb it should not climb above them before reaching them - if you can reproduce this please let me know and I'll show the programmers.

[Rickie Welsh 27]

Hello Ceri, I dont fly using ATC. You will find flying in the UK that the altitude restrictions are usually 5000/6000ft and usually last a fair distance. Look at your route in the FMC andsee how far the restriction alt is per waypoint. Go to the Init Page and see the LSK6R is by default 18000 for USA change this to your Alt Restriction 5000/6000ft and follow your route to where this restriction ends, and insert to Alt Window the altitude ATC give you and using Vnav this will automatically change and so on during your flight. Hope I am right and this helps. richard welsh.