An inspector has found "systemic safety issues" in the design and operation of hospital landing sites, after a woman died last year.
Jean Langan, 87, was blown over while a helicopter was landing at Derriford Hospital, Plymouth on 4 March 2022.
She was walking through Car Park B after an appointment with her niece when she was hit by high levels of downwash from a HM Coastguard helicopter landing on the helipad above.
Downwash is the change in direction of air deflected by the aerodynamic action of a helicopter rotor blade in motion, to help create lift.
Another person was seriously injured in the incident.
A report from the Air Accidents Investigation Branch released on Thursday 2 November has revealed that the risks of the helicopter landing were "not properly assessed."
University Hospitals Plymouth NHS Trusts said it made "immediate changes" to the operational running of the helipad following the incident to manage the risks.
The report found that members of the public were not stopped from being present in the area around the hospital's helicopter pad when it was landing and that communication between the helicopter operators and hospital staff was "ineffective."
It also found that several downwash complaints and incidents had been recorded and investigated in the past, but the actions taken were "not effective" in preventing future occurrences.
Crispin Orr, Chief Inspector of Air Accident said the investigation revealed "systemic safety issues" around the design and operation of hospital helicopter landing sites.
He said: "Helicopters used for search, rescue and emergency medical services play a vital role, but it is essential that the risks associated with helicopter downwash are understood and well-managed."
According to the report, the hazard of helicopter downwash in the car parks next to the helicopter landing site was "not identified" and the risk to members of the public was "not properly assessed."
It added that the Derriford Hospital staff had "insufficient knowledge" about helicopter operations to safely manage the downwash risk around the site.
Mr Orr said that safety issues around the operation of hospital helicopter landing sites need to be addressed at a "national level."
"The investigation has raised awareness of this issue and been a catalyst for important safety action, which has been taken to mitigate the immediate risk," he added.
The report has made nine recommendations to help improve the coordination between helicopter operators and people working in the hospital to help prevent a repeat incident.
A spokesperson for University Hospitals Plymouth NHS Trust said: "We are very sorry that this tragic incident happened and our sympathies go to Ms Langan’s family and everyone affected.
"We have supported the AAIB’s investigation and made immediate changes to the operational running of the helipad as a result of this incident.
"We closed the helipad to those aircraft over 5 tonnes such as the coastguard helicopter, closed the car park adjacent to the helipad to patients and visitors to reduce the risk of downwash and increased signage in the area. These changes were made in March 2022 and will remain in place for the foreseeable future.
"The AAIB report made a number of national recommendations which will lead to further improvements for hospital helipads across the country and we will work closely with the relevant national bodies to implement those recommendations in Plymouth."