What is the average speed of a plane?

Planes come in all different shapes and sizes, e.g. passenger planes, small propeller planes and jet-fighters.
The following overview shows the average speed of various planes:

 Type of plane   Average speed 
 Small plane  124 mph (200 km/h) 
 Airliner  621 mph (1.000 km/h) 
 Jet  1243 mph (2.000 km/h) 

What influences the average speed of a plane? 

The weather has a large influence on the average speed of a plane. For instance, a plane flying with tailwind can reach far over 621 mph (1,000 km/h), whereas flying against strong winds decreases the speed to an average of only 373 mph (600km/h).

Has the average speed of planes increased over the years?

Yes, the average speed of planes is still increasing. Advances in technology, in particular, have ensured that airlines can continue to increase the average speed of their planes. To compare: a current passenger plane flies an average 621 mph (1.000 km/h), in the 70’s the average speed was 497 mph (800 km/h).

What is the fastest plane in the world?

The X-15 rocket plane is the fastest manned plane ever built. This plane has a top speed of 4000 mph (6.437 km/h). The fastest unmanned plane is the Falcon-HTV-2. This plane is developed to react fast to terrorist attacks and can reach a speed of over 12427 mph (20.000 km/h), meaning it can fly from Sydney to London within an hour!

See besides average speed of a plane also: 
Average Cycling Speed
Average Bike Speed
Average Train Speed
Average Walking Speed