Going Up and Down

Verb to get onto an airplane
are boarding
The passengers are boarding the aircraft -- up the airstairs and a small step onto the plane.
Verb (of an aircraft) move slowly along the ground before takeoff or after landing
is slowly taxiing
Our plane is slowly taxiing down the runway. With a line like this it could be 30 minutes until we take off!
Verb leave the ground and begin to fly
is taking off
Finally the plane is taking off. It isn't raining yet and liftoff goes smoothly.
Noun the act of rising or moving up
ascent
The plane begins its ascent -- amazing how quickly it climbs above the clouds.
Noun the act of going from a higher to a lower place or level
descent
Now the flight is almost over and the plane is in its descent. I think we're going down too quickly!
Noun official authorization for something to proceed
clearance
The captain gets clearance for landing. We will be on the ground in a just a few minutes.
Phrase when an incoming plane makes contact with the ground
touch down
Touch down! Brakes and reverse engines slow the plane down quickly on this short runway.
Verb to leave an airplane
disembarking
Finally the plane has arrived. Passengers are disembarking -- only a few steps to the terminal.