I have been poking around, but cannot seem to find the info on this - which means that as soon as I psot this, I will stumble across it --- but...

When setting up a multiple waypoint mission, how do I make it so that the altitude of a waypoint must be reached before going to the next waypoint? For instance, if I want to loiter at a waypoint at 5 meters then ascend at the same Lat/Long position to 20 meters, then when I get to 20 meters, fly to the next set of coordinates?

WP1: LAt1, Long1, alt:5M

WP2: Lat1, Long1, Alt:20M

WP3: Lat2, Long2, Alt: 20M

When I try this, it seems to only be considering the Latitude and longitude for determining if it is at the waypoint. So what ends up happening is that when it tries to go to WP2, it sees that it is already at the correct lat and long, and starts off to WP3. So instead of ascending in place, it angles up to WP3.

Is there not a command somewhere to set altitude directly? If not, is there a way to have 3D instead of 2D Waypoint conditions that must be met?

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In case I am not being too clear, what I am looking for is either a setting that says "Hit the altitude to consider the waypoint reached" or else separate "AscendTo" and DescendTo" commands. This may exist, but I cannot find it. 

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I asked a similar but not identical question. I got this answer from Art Whaley. It may help you....

First off - I fly in Oklahoma where the ground is flat and so I haven't USED verify height.  But according to the manual, it doesn't exactly do what you want, because it only checks and adjusts the ground altitude at waypoints.

By default, the mission planner uses 'above launch site' as the reference for all altitudes, and with 'verify height' turned on it uses 'above current ground level'.

so with verify height turned on, you could set

WP1 at altitude 100' a little bit upwind of the takeoff site

WP2 at altitude 100' on top of the mountain

WP3 at altitude 100' at the target site

WP4 at altitude 100' on top of the mountain

WP5 at altitude 100' a little bit downwind of the takeoff site.

or with verify height turned off you would set

WP1 at 100'  (above launch site)

WP2 at 1100' (above launch site)

WP3 at 500' (above launch site)

WP4 at 1100' (above launch site)

WP5 at 100' (above launch site)

or with absolute altitude turned on it would be

WP1 at 1100'

WP2 at 2100'

WP3 at 1500'

WP4 at 2100'

WP5 at 1100'

All of these three courses are exactly the same - they're just different ways of entering the values.  If you do this, the aircraft will take off at 1000' ASL, fly to 1100'ASL, ascend to 2100' ASL to cross the mountain with 100' of clearance, descent to 1500' at the target location, climb back to 2100' to get back over the mountain and then return to 1500' and lined up for a landing.

If you just set WP 1 and 3 and 5 from the above example, even with verify height turned on, you're going to crash into the mountain.  The MP only checks and adjusts for terrain height at waypoints.  To my knowledge there's no way around this right now.  Maybe in the future the Sonar sensor or a machine vision system could let you actually see the terrain, but right now we just have to plan ahead for it ourselves.  There's not enough memory in Ardupilot to store the terrain height values for every place we could possibly fly it, and the programming doesn't RELY on the base station for anything when on an Automatic path - all of the decisions are made in the air so if telemetry is lost, the vehicle tries to complete the mission.

Is there a reason you don't want to give it a couple of extra clicks to make sure you get over the mountain?   I'd personally set my 2100' ASL waypoint in FRONT of the mountain and another 2100' WP substantially BEHIND it to make sure I'm up high way before I need to be and back down after all risk of collision is passed.  And for that matter, I'd want more than 100' of spare clearance going over a mountain, but I'm just using that number for easily following the discussion!

Scott, for ArduCopter 2.9.1 it separates navigation of waypoints and height. So, it is trying to attain the height, but as you say, that's not a requirement of considering a waypoint to have been reached. In AC3.0 I believe they've changed it so that it is attempting to track directly toward each 3D waypoint rather than treating 2D position and height separately, though I haven't tested to verify if that's actually working.

Not sure about ArduPlane.

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