The pitot was first invented well before aircraft, yet early aircraft lacked an airspeed indicator (ASI). What aircraft first had a pitot-based ASI, and when?
From the book History of Technology, Volume 18, page 99:
The first reliable air speed indicator was a U-tube manometer called the velometer, designed and patented by Frank Short at the Royal Aircraft Factory at Farnborough in 1912. Connection to a pitot-static head on a wing strut allowed the measuring element to be well away from the slipstream, while the indicator could be placed in front of the pilot. The velometer was manufactured by Casella and Elliott Brothers and was often supplied to military aircraft on a standard instrument panel.
It reminds me of the question: What was the first aircraft fitted with both an FDR & CVR?
Since the technology is not aircraft specific, say unlike the first flaps/air-brakes, the supplier can fit different aircraft at the same time. Which makes it near impossible to find the exact airplane as the above text suggests by mentioning a standard panel.
Interesting find: in 1910 there was a £5 prize (~£550 in 2017) for a speed-alarm design.