Originally Posted by
Airone2977
When selected on the ground, LNAV engage at 50ft, VNAV at 400ft.
The issue with VNAV armed on the ground is in the case of engine failure after V1. If you didn't carrefully select EO acc Alt on Take off page 2, it will level off and accelerate to VREF40 + 70 at 1000ft AGL. It could be hazardous expecially if you have high terrain in the vicinity
Just a minor, though pertinent observation here. The 'it' you refer to above is the automation (either Flight Director or Autopilot). At my airline, our practice is to not engage the A/P in an engine out situation until the flaps are retracted, but this might be different elsewhere. That being said, the aircraft should not level off unless the flying pilot wants it to level off, which speaks to the issue of automation dependency. One of the biggest challenges of modern airliners is to know when to override what the automation is trying to do. Yes, ideally one should set the AFDS panel correctly, but if this was not done or done incorrectly, then the pilot needs to be able to fly with reference to the attitude indicator and not the FD bars.