Emergency services are currently at the scene and Brighton Road is closed between New Salts Farm and the High Street.
Initial reports suggest that one person has died.
A Sussex Police spokesman said: “The alarm was raised at 4.28pm.
“Initial accounts suggest the aircraft was in collision with another and then crashed on a recreation ground close to the airport.
“Police have established a cordon around the wreckage at Adur Recreation Ground and at Beach Green.
“It is believed at this stage that the second aircraft involved landed safely.
“No-one is believed to have been injured on the ground.”
Brighton Road is likely to remain closed throughout the evening rush hour.