Public acceptance – Harder than you (might) think

Deep Dive

Getting the public onside with new aircraft flying in their neighbourhood might be harder than you think. 

Whilst attention has quite rightly been focused largely on certification, and more recently infrastructure to support flying, it is fair to say less has been given to what the public thinks of it all. People have been objecting to change in their area since Icarus and Daedalus were the forerunners in advanced air mobility.

The big wins most of the air taxi OEMs shout about are the noise reductions compared with today’s aircraft – both in decibel level and tonal content. Take Archer’s Midnight eVTOL which the firm says will produce an audible sound of about 45 decibels (dBA) at a cruising height of 2000ft. On a logarithmic scale, 45 dBA will sound not dissimilar to working in a quiet office and won’t overbear a normal conversation being had by those below.

Joby’s aircraft operates at a similar sound level. Last year, NASA published “Acoustic Flight Test of the Joby Aviation Advanced Air Mobility Prototype Vehicle” which found Joby’s eVTOL created 65 dBA on approach at a distance of 330ft from the flight path and/or landing zone. (NASA says 330ft (100 metres) is a distance consistent with typical community proximity to the aircraft). However, the “benign nature” of the sound, compared with that of a drone or helicopter, means the aircraft is closer to white noise and will blend into the overall soundscape more easily, said NASA. Making the aircraft virtually inaudible to someone in a “bustling business office”.

Kyle Pascioni, research aerospace engineer and acoustics lead of NASA’s AAM National Campaign and also the lead author of the technical paper, said: “Obviously, for helicopters, you get that impulsive sound due to the main rotor blades, or for airplanes, the propeller sound. For this vehicle, their propellers are rotating at slower rates. You don’t hear that characteristic rotor or propeller sound. It was much more benign. We talk about tonal content and broadband content of a sound in acoustics. Joby’s vehicle was much more broadband, with broadband being like white noise.”

The above findings are positive for the future of AAM acceptance. Noise reduction is massive when you pit eVTOLs against traditional helicopters or fixed-wing aircraft, especially when in close proximity to a landing zone. However, there are a number of cases (with instances sure to increase) of the public objecting despite the proposed reductions in noise pollution and for a host of other reasons too.

The recent and very public rejection of plans to integrate air taxi services into the public transport ecosystem in Paris next summer was backed unanimously by city councillors. Volocopter, in partnership with Groupe ADP and the Paris Region, announced its blueprint for air taxi operations to launch in line with the Paris 2024 Olympics earlier this year at the Paris Airshow. Starting with three connection routes and two tourist round-trip flights, utilising several aircraft, operations will begin from five vertiports, said developers.

Volocopter has not shied away from work to mitigate noise impacts from its aircraft on the public below. From 100ft away the firm’s 2X aircraft has a signature of 75 dBA – same as a vacuum cleaner. When flying overhead at any altitude of 393ft, the 2X creates a 65 dBA signature. To ensure disturbance is kept to a minimum, flights will be operated at specific times in various parts of the city. Despite this, members of the Conseil de Paris rejected the plans as “absurd”. Councillors described the project as an “ecological aberration”. Paris’ deputy mayor, Dan Lert, said the plans were “a totally useless, hyper-polluting gimmick for a few ultra-privileged people in a hurry”.

Regardless, plans may still go ahead with the Ministry of Transport set to make a final decision at the beginning of 2024. That said, the stiff opposition, focused largely on the wealth of the users and climate impact of aircraft, could be a sign of things to come for service developers. A sign that it could be harder than might first have been thought to establish routes in close proximity to the public.

Aside from the Conseil de Paris’ opposition, there are few other public examples of localised opposition to AAM operations – maybe because developers largely haven’t got that far yet. But people have been objecting to drone operations for a few years now and they’ve been opposing heliport plans for decades.

The Irish Aviation Authority was faced with a disgruntled homeowner on the outskirts of Dublin. The individual opposed the operation of a drone delivery trial which included a flight path directly over their home. Declan Fitzpatrick, CEO, Irish Aviation Authority told a panel Revolution.Aero hosted recently: “For one of our local operators, the biggest challenge was a lady with a parrot which used to get upset when the drone went overhead. The solution was to vector the drone around her house, something they are still doing to this day.”

Fitzpatrick points to the four key principles – safety, privacy, security and the environment – embedded in EASA’s rules for UAS. The local regulator will deal with safety and security, but there is a small gap in responsibility for the environmental and privacy requirements, he says. A recent study commissioned at European level found that privacy came out above safety as a societal requirement for AAM and UAS operations, mainly because safety was taken as a given.

Whether acting as an individual, collective or commanding the help of a local representative, the public can put up meaningful opposition to new airborne operations. If you thought that opposition because of economic access, ecological impact or pet disturbance was extreme, what about disruption to piano lessons? Desmond Ross, MD at Pegasus Aviation Advisors encountered such opposition when attempting to get plans accepted for a heliport in Sydney, Australia.

“I don’t think OEMs understand the problems they could have from the general public who will probably never fly on these aircraft,” says Ross, who assists aircraft developers tackling public acceptance issues. “We tried to set up a heliport at a site in Darling Harbour, Sydney, built on the site of a disused railway yard. Everyone wanted it including the city council, but the amazing objections from the local people prevented it happening straight away. It did happen eventually but on a more limited basis because of the opposition.”

“To think that the helicopter operations would be noisier than the old trains shunting around was unbelievable. One woman in particular claimed her daughter’s future was going to be destroyed by helicopters flying over because she would not be able to practice her violin. It went viral for the time,” he says. The individual woman lived about 4km from the proposed site at a location where air traffic would pass overhead at a minimum altitude of 1,000ft – producing a noise signature of 78 dBA at most (about the same as a vacuum).

You might be thinking, but studies have proven electric air taxis are way quieter even in approach, so this instance should be avoided. “The point is that people become quite emotive, they don’t care about the reality and the logic. They just decide they don’t want to have it and that’s it,” says Ross. When operational, the disused train yard would produce noise signatures of around 95 dBA for those in close proximity. This is similar to the noise signature of a medium-sized helicopter on the ground (85-95 dBA). The difference is that trains are widely accepted as a key piece of transport infrastructure, helicopters are not in most places and eVTOLs even less so. A lot of people don’t like drastic change, especially to their neighbourhood.

When hip-hop group Public Enemy released “Harder Than You Think” I bet they didn’t see the potential link to society’s acceptance of air taxi services. But the fact is that members of the public acting even as individuals can put up stiff opposition to new aerial operations in their locality. If the public see you as an enemy it might well be harder than you think to build a vertiport and operate services at sufficient volume to turn a profit.

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