The Brazilian Air Force is conducting operational testing of the KC-390 transport / tanker aircraft at Campo Grande air base.
The first trials were successfully completed by dropping paratroopers from the Embraer-built aircraft.
Brazilian Air Force KC-390 programme technical manager colonel Claudio Evangelista said: "There were major concerns about the paratroopers' exit from the fuselage because there is an aerodynamic flow around a new airframe.
"Fortunately, the feedback we received from the military was very positive, they reported that the exit was very smooth."
The trials will involve dropping of supplies and checks of the stability of extractor parachutes.
During the scheduled trials that will continue until 9 July, the aerodynamic modifications of the aircraft will be examined.
The test results will support the final development and certification of the KC-390 aircraft.
Embraer engineer André Gama said: "It's almost a war exercise.
"In a few days, the campaign will expand to involve over 200 people, including Embraer professionals and military personnel."
Embraer has developed KC-390 aircraft, under a $1.3bn development order awarded by Brazilian Air Force in 2009.
The aircraft will replace the 22 Lockheed Martin C-130E/H and KC-130 that are currently a part of the Air Force.
The transport jet comes with V2500-E5 powerplant, landing gear system, two head-up displays (HUD), self-defence system and night vision goggle (NVG).
BAE Systems will supply and install flight control electronics in the KC-390 transport aircraft.
Image: Embraer's KC-390 prototype. Photo: courtesy of WantuilDepaula.