Detectives are appealing for information after a paragliding collision in Brentwood on Friday April 10.
Police were called to reports that a man in his 30s had been injured at the disused Priors Golf Club in Noak Hill shortly before 3.20pm.
The man remains in hospital.
Anyone who witnessed the incident, or has dash cam or mobile phone footage which may be relevant, is urged to come forward and speak to officers.
Police are also particularly keen to locate the canopy of the paraglider, which was not on scene when officers arrived.
If you have information please call Brentwood CID on 101 and quote the crime reference number 42/53075/20.
If you wish to remain anonymous you can speak to Crimestoppers by submitting information through their website or calling 0800 555 1111.