Speed comparison: UFO versus a Qantas A380 airbus

Here are two consecutive images taken 0.47 seconds apart of a Qantas A380-800 airbus with contrails cruising at high altitude, travelling west over the Perth hills. There are three different fast-moving craft (UFOs) captured in two images. While the airbus moved only 11 mm in 0.47 seconds when measured on the images on my computer screen, craft 1 moved 204 mm or 18.55 times faster than the airbus in the opposite direction. The Qantas A380 airbus has a cruising speed of 900 km/h (560 miles/h) at cruising altitude (en.wikipedia.org/wiki/Airbus_A380). This means that craft 1 must have been travelling at around 16,690 km/h! Craft 2 and 3 are captured only once in the two images and their speed can therefore not be estimated.