At what point do I engage VNAV & LNAV

[markadeane 272]

Hi Clayton, possibly due to your loading? In the NG, VNAV will definitely not command a rate of climb that slow at lower levels.Towards the end of your climb the slower rate is to be expected at certain temperatures and weights.

[clayton4115 56]

thanks Markthat answers my question as i have been fiddling around with that darn load editor.

[macpac22 0]

But isnt the use of Vertical Speed mode standard procedure especially if you get TCAS warnings on climbs or descents? I use V/S on my SID and STARS as i find its better to use so i can wind some speed off and have a continous rate of climb/descent. In most cases on a SID with an altitude restriction, after the initial climb and you clean the aircraft , the 744 will rocket towards climb speed and then pitch up to gain altitude..at this point i find flickin over to v/s is beneficial. This gives me the green arc so all i do is adjust my rate of climb to sit the green arc over the waypoint that has the altitude restriction. As i near the waypoint i can request a higher altitude without the need to level off and then initiate another climb phase.But then again sometimes im lazy and let VNAV do its job :)

[Mats_J 2]

Paul,My two cents on some of your comments:>But isnt the use of Vertical Speed mode standard procedure>especially if you get TCAS warnings on climbs or descents?As far as I know the 'standard procedure' is to override the A/P and climb/descend manually quickly as h**l. It's a matter of seconds here, the last thing you want to do is to start fiddeling with the AFDS.>I use V/S on my SID and STARS as i find its better to use so i>can wind some speed off and have a continous rate of>climb/descent. In most cases on a SID with an altitude>restriction, after the initial climb and you clean the>aircraft , the 744 will rocket towards climb speed and then>pitch up to gain altitude..at this point i find flickin over>to v/s is beneficial. The same benefits can be achieved with LVL CH as well and you'll get the speed protection. Even if using V/S during descents is not as 'bad' as using it during climbs and cruise. If you are lightly loaded you should try to derate your TO and CLB thrust max settings. This way you shouldn't be 'rocketing' as much. ;-)Cheers,

[macpac22 0]

Thanks for your replies Mats,i find LVL CH a bit of a handful to manage in the 737, actually i find the 737 a lot more difficult to fly precisely than the 747. I guess i dont really understand how LVL CH works exactly..does it give variable climb/descent rates? Like say i was flying at 275 knots at 15000ft and want to descent to a waypoint and cross it at 6000ft at 180knots. Dial in 6000ft in the MCP Altitude window and then hit LVL CH and change the speed to 180knots. Now the aircraft should first slow down to 180knots before descending right? Then the aircraft will nose down to descend, at this point a steep descent could be in order due to the time the aircraft spent slowing down therefore making a fpm descent that would be unpleasant :) and might actually increase the speed of the aircraft. Do i have that right? :)

[Mats_J 2]

>I guess i dont really understand how LVL CH works>exactly..does it give variable climb/descent rates? Like say i>was flying at 275 knots at 15000ft and want to descent to a>waypoint and cross it at 6000ft at 180knots. Yes it gives you variable vertical rates. The scenario you've described above is a tricky one without VNAV as you can only guarantee speed (LVLCH) or altitude (V/S). Basically it's down to your planning skills as the commander to make sure you'll arrive at the right speed and altitude if not using VNAV.>Dial in 6000ft in the MCP Altitude window and then hit LVL CH>and change the speed to 180knots. Now the aircraft should>first slow down to 180knots before descending right? Then the>aircraft will nose down to descend, at this point a steep>descent could be in order due to the time the aircraft spent>slowing down therefore making a fpm descent that would be>unpleasant :) and might actually increase the speed of the>aircraft. >>Do i have that right? :)You got that right! :) What I would do is probably leave the original speed and check with the green banana to see that I will arrive at or preferably before my intended waypoint. If I do arrive at altitude before the waypoint I will have some time to then slow down to desired speed.My two airmchair pilot's cents, ;-)

[macpac22 0]

Thanks Mats sounds logical to me..will have to practise :)