A student pilot suffered a "laser burn" to his eye when a green beam was shone at the plane he was flying.
Police said two training aircraft were targeted on two consecutive days while they were flying over Charlbury and Chipping Norton in Oxfordshire.
Leading Edge Aviation, a pilot training academy, said a 21-year-old man was taken to hospital after one plane was subjected to a "laser attack".
The training flights had taken off from London Oxford Airport in Kidlington.
Thames Valley Police said the first aircraft was carrying three people on 4 February when a laser was shone at about 19:15 GMT in the Chipping Norton area.
After the pilot suffered an eye injury, the plane safely landed at London Oxford Airport.
Leading Edge Aviation said the eye injury had left the student "currently grounded" but added he was expected to make a full recovery and return to training.
The following evening at about 17:45 GMT, police said a laser was shone at an aircraft about three miles north of Charlbury, however, nobody was injured on that occasion.
Andy McFarlane, Leading Edge Aviation CEO, said he was "appalled" by the attacks.
He said: "We are proud of the professionalism shown by our crew in taking such decisive action, without which the consequences could have been far more serious."
PC Renee Gabbey-Cristofini said the police did not know "exactly the origin of these laser attacks".
She said: "These were extremely reckless acts which placed both aircraft in significant danger.
"The recklessness of such acts not only endangers the aircraft and all passengers on board, but also those on the ground."