Safety taking off in the air taxi industry

Regulations will be needed to address key safety issues in the burgeoning air taxi industry, according to a new study.

A recent paper by RMIT University’s Uncrewed Aircraft Systems (UAS) research team measures how sudden wind gusts form around city buildings and destabilise aircraft, creating significant safety challenges for air taxis and drones in less than one second. Low-flying aircraft such as air taxis would be at particular risk because they land and take off at low speed.

The air taxi market now is drawing closer to its launch, with companies such as Boeing, Hyundai, Airbus and Toyota building fleets that will see commuters able to travel through the sky. Europe and the US have already drafted new rules to pave the way for air taxis to begin operations within the decade, and Australia’s Civil Aviation Safety Authority (CASA) is due to follow suit.

Lead researcher Dr Abdulghani Mohamed, an aerospace engineer at RMIT, has studied wind gust dynamics for over a decade. He said that this aspect needs to be adequately addressed by regulations in Australia and overseas before the city skies are filled with air taxis and other drones.

Mohamed also said air taxis and drones will need more power for landing or taking off in cities when compared with an airport or an open space.

“These aircraft need powerful motors that can rapidly change the thrust generated by the propellers to rapidly force the vehicle back on course, a process which requires more energy,” he said.

Notional flow field about a building generated by atmospheric winds.

Keeping the skies safe

Regulations for Advanced Air Mobility (AAM) aircraft, such as future air taxis, are being compiled around the world, including the US and Europe. The RMIT team emphasised that weather frameworks are needed to ensure this new technology is safe and reliable.

“Regulations and certification need to specifically address safe operation when traversing building flow fields,” Mohamed said.

He argued that site-specific wind simulations and measurements are essential to identify hazardous regions.

“As we determine the location of vertiports — where these vehicles will take off and land — we also need to determine hazardous regions to avoid. This will enhance safety and reduce interruption of a fleet due to wind conditions,” he said.

“In Australia, it is not clear yet whether this falls under CASA’s jurisdiction or the Bureau of Meteorology; however, air taxis will need to be provided with weather information at much higher resolution and faster rates than currently possible. This is important for flight planning.

“The margin of error will be much lower than at airports, where large aircraft can tolerate much stronger gusts. We won’t have that flexibility with air taxis in cities.”

Moving forward

“Purpose-built vertiports mean we could integrate geometric design features to reduce hazardous flow conditions from occurring, and we are exploring this in our current research,” Mohamed said.

“Existing buildings can also be repurposed as vertiports but may require modifications to improve the aerodynamics near the landing pads. The effectiveness of such design features can be assessed through either scaled experiments in wind tunnels or through full-scale measurements.

“Extensive wind flow mapping at full scale will no longer be daunting in the future. We are continuing to develop our wind-sensing drones — a swarm of drones instrumented with wind anemometers — to very accurately map around large infrastructure.”

‘Gusts Encountered by Flying Vehicles in Proximity to Buildings’ is published in the journal Drones. The study’s recommendations could help shape the regulation of vertiports, flight paths and air taxi requirements in Australia and potentially globally.

The researchers are continuing research into wind gusts around buildings, with further exploration of different building shapes that may minimise adverse effects. They are also continuing to study the sensitivity of vehicles to gusts and turbulence, as well as flight-stability technologies.

Images courtesy of RMIT University.