Jump to content

Archived

This topic is now archived and is closed to further replies.

suchw

Difference between Level Change and Alt Intervention

Recommended Posts

Hello Anybody know the differentiation between Level change and Alt intervention when in Vnav path


Wayne such

Share this post


Link to post
Share on other sites

ALT INT is to clear the FMC up to the next assigned altitude. Level change is more about holding a speed to a selected altitude. To the best of my knowledge.


A Walker

Share this post


Link to post
Share on other sites
thanks anybody else want to chime in here
LVL CH let you choose a speed in the MCP, so the autopilot adjusts the rate of climb/descent to keep the speed you set in the MCP.ALT intervention is like when you go on CRZ page and change the altitude in the CRZ ALTITUDE...

SAFIR OTHMANE

 

 

Share this post


Link to post
Share on other sites

You are mixing your modes!! For vertical navigation you can either use LVL CHG, VNAV or V/S. Selection of any of these will knock out the previously selected mode. So if in VNAV PTH pushing LVL CHG will cancel VNAV. ALT INTV will remove the next constraint from the FMC. For example on a SID first waypoint has an altitude constraint of 4000', controller clears you to 6000' before you reach the waypoint. To stop the aircraft leveling off at 4000' in VNAV PTH you set 6000' in the MCP and press ALT INTV which clears the 4000' restriction and allows you to continue climbing. It's a complicated subject, if you want more detail I'd be happy to help. Andy

Share this post


Link to post
Share on other sites
Hello Anybody know the differentiation between Level change and Alt intervention when in Vnav path
LVL CHG climbs at N1 Limit at the MCP Speed or descend at idle and MCP SPDVNAV will also climb at the N1 Limit but at VNAV SPD or attempt to descend at idle and the econ speed for your cost index. LVL CHG doesn't care about any restrictions in the LEGS page (Cross AT, BELOW, ABOVE), only what's in the ALT SEL window.VNAV will follow VNAV PATH, honoring those restrictions. I assumed you meant climbing and descending, not what does pressing the ALT INT button do.

Matt Cee

Share this post


Link to post
Share on other sites

×
×
  • Create New...