Tarawa trigger when landing

Hello guys, I would like to know how I could make a trigger when a Harrier lands in the Tarawa. I do not know the high of the Tarawa so I could not use UNIT BELOW ALTITUDE condition. I tried setting 0 using UNIT BELOW AGL ALTITUDE but with no success. Any ideas?

Thanks

Create a trigger zone the approximate size of the Tarawa deck.

A combination of UNIT INSIDE MOVING ZONE (plane, zone, tarawa), UNIT'S SPEED LOWER THAN, and UNIT'S ALTITUDE LOWER THAN should do the trick. Remember the altitude trigger will be expressed in meters.

To determine the correct altitude, start a plane on the deck of the Tarawa and observe the altitude shown in the F2 view.

Place a unit on the tarawa, start the mission, go to F2 view and read the altitude in the status bar

Or using a simple script:

Handler = {}
function Handler:onEvent(event)
if event.id == world.event.S_EVENT_LAND and event.initiator == Unit.getByName('Player') then
trigger.action.setUserFlag('1', true) 
end
end
world.addEventHandler(Handler)