Embraer KC-390 takes maiden flight

[Speedywheels]

It's a trailing static probe that provides accurate data to the test aircrew. Theory is the cone flies outside the aircraft wake and provides accurate P/S data to allow calibration of the on-aircraft systems. Commonly used on early test flights to ensure the data coming directly from the aircraft system is accurate and not being adversely affected by aircraft attitude.

Edit: Wot he said ^^^^^^^