The speed of an airplane is measured in kilometers per hour (km/h) or miles per hour (mph) with respect to the surrounding air.
The direction of an airplane's flight is important because it determines the flight path and destination of the airplane. It also affects the flight time and fuel consumption of the airplane.
The airplane maintains a constant speed and direction by adjusting the thrust of the engines and using control surfaces such as the rudder, elevator, and ailerons to control the direction and stability of the airplane.
"Due north" means that the airplane is flying directly towards the north, or 0 degrees on the compass. This means that the airplane's heading and the direction of the flight path are aligned with the north.
Air resistance, also known as drag, can affect an airplane's speed and direction by slowing down the airplane and causing it to deviate from its intended flight path. Pilots must adjust the airplane's speed and use control surfaces to counteract the effects of air resistance in order to maintain a constant speed and direction.