The Australian Transport Safety Bureau (ATSB) has issued a safety advisory after a number of occurrences in which pedestrians were injured by rotor wash around hospital helicopter landing sites.

The notice advises medical transport operators and hospital helicopter landing site operators to engage with one another and ensure local procedures are sufficient to mitigate the risk of rotor wash associated with larger helicopters, such as the Leonardo Helicopters AW139.

It stems from an ATSB Aviation Data and Analysis Report analysis of a series of incidents over the last five years, which considered the common factors, existing regulatory guidelines, and ways to mitigate the effects of rotor wash.

“Of the 18 helicopter rotor wash incidents reported to the ATSB in the last five years, nine occurred at hospital landing sites,” ATSB director, Transport Safety, Dr. Stuart Godley, said.

“Six of those nine occurrences resulted in injuries to pedestrians who were within approximately 30 meters of the landing site, and flight crew were not aware of the presence of pedestrians in all cases.

“In fact, in most instances, flight crew were not aware any incident had occurred at the time.”

Significantly, there were no reported occurrences of rotor wash related injuries at hospital HLS prior to the notable increase in the utilization of AW139 for medical transport operations from 2017.

If the recommended rotor wash exclusion area for the AW139 had been applied at each HLS, it would have reduced the risk of the pedestrians being injured.

The ATSB’s report notes a range of key factors contribute to the effects of rotor wash, including the weight and size of the helicopter, the main rotor size, disc loading, prevailing winds, and flightpath.

“The flightpath is the only element that can be managed by the pilot in accordance with the operator’s procedures,” Godley said.

“But as these occurrences demonstrate, pilots may be unaware of the presence of pedestrians in the vicinity, and therefore be unable to adjust their flightpath accordingly.

“As such, hospital landing site owners and helicopter owners should ensure pedestrians are not affected by rotor wash, by implementing appropriate risk controls for their landing sites, in addition to the helicopter operating procedures.”

Risk controls may include physical barriers, warning devices such as sirens, lights, high visibility warning signs, painted lines on nearby public thoroughfare to alert pedestrians to the rotor wash danger area, an inspection schedule for the landing site facility and surrounding area, and establishing a closed-loop reporting system.

Read the Safety Advisory Notice: Safety at hospital helicopter landing sites. Read the Aviation Data and Analysis Report: Downwash incidents at helicopter landing sites.