Niki, a subsidiary of Air Berlin, is launching what is billed as the world’s shortest international flight on April 1st. The Vienna to Bratislava flight is scheduled to last a mere 10 to 20 minutes (depending on the source) between take-off and landing.
Currently, there is a direct train connection and intercity bus service between both cities. They take approximately 1 hour from station to station and cost much less than the flight. Taking check-in time and costs into consideration, most people (other than aviation enthusiasts) will probably continue to just use the train.
The airline acknowledges the route will be most useful as a transfer service for commuters catching a connecting flight in Vienna.