The concept of a flying car is not a new one. Over the past 70 years, quite a few flying vehicles have been prototyped and tested. The inventors have always had a clear goal, namely to create a hybrid of an aircraft and a car. It is, however, a seemingly simple goal with many technical challenges.

Essentially, flying cars are small, piston-engine aircraft capable of carrying one to four people, which can also be used as road vehicles. They are powered by one engine, for both flying and driving, or by separate engines for each mode. Due to limits in road lane width and parking space, flying cars are typically equipped with folding wings.

Two fundamentally different regulatory systems

What adds complexity to the design is the need to meet minimum legal safety requirements for operation both as an aircraft and as a car. This involves complying with the rules of two fundamentally different regulatory systems. 

The design, operation and maintenance of aircraft are controlled by strict safety rules. These rules are established and enforced by cross-national regulating bodies, such as the European Aviation Safety Agency (EASA) in the EU and the Federal Aviation Administration (FAA) in the United States.

Small aircraft used in non-commercial operations, such as recreation, are subject to a lighter set of regulations compared to large, passenger-carrying aircraft.

Nevertheless, these regulations are still highly comprehensive, covering aspects like structural strength, reliability, flight performance characteristics, handling procedures, inspection and maintenance schedules and licensing requirements for pilots and technicians.

In contrast, car safety is regulated in a more fragmented manner. While countries may adopt international standards and commonly agreed rules, such as those followed by EU member states, each has its own national regulatory body. That said, the regulatory philosophies of the aviation and automotive industries share, at least at a high level, some similarities. 

As things stand, the regulatory framework, the specific rules and how they are implemented remain far apart. For example, in car safety, one of the key areas of regulation focuses on ensuring occupant protection during crashes and improving pedestrian survivability.

By comparison, safety regulations for small aircraft typically require only basic occupant restraints (seat belts), with no specific provisions for crash scenarios or survival criteria.

For a flying car to be considered safe under both regulatory systems, it would need to satisfy both sets of occupant and pedestrian protection requirements, without imposing unnecessary burden on the vehicle's design, performance, or usability.

To better understand the safety requirements that a flying car must meet, it is useful to examine the cases of the Klein Vision AirCar and the Terrafugia Transition.

A prototype of the Klein Vision AirCar has been certified and registered under EASA regulations by the Slovak Transport Authority, while, two prototypes of the Terrafugia Transition have received certification and registration from the US FAA. However, it is unknown whether any prototypes have received approval from regulatory bodies for road use as cars. 

A closer look at the publicly available information on the Terrafugia Transition vehicle offers further insights into the design features that flying cars should possess.

The passenger cabin of a flying car must be reinforced compared to that of a light aircraft, as it is required to meet automotive crash test standards – designed to withstand deceleration forces of up to 30g, compared to the 9g required for light aircraft restraint systems. Moreover, the vehicle would need to include additional systems specific to ground driving, such as steering, suspension, braking and visibility.

Vulnerable to debris

Meeting these requirements adds weight to the vehicle, which in turn increases the likelihood of stall (loss of lift) and makes take-off and landing more challenging for the pilot. The aircraft engine and outer surface are more vulnerable to debris encountered in road environments.

For example, the impact of even a small stone could be catastrophic for a propeller blade. This presents additional design challenges, as the vehicle must incorporate features that ensure roadworthiness. 

Operation of the vehicle must be carried out by individuals qualified under aviation safety regulations. From a maintenance perspective, a flying car must comply with aviation safety regulations. This means that only a licensed aircraft maintenance technician is allowed to perform and certify any work on the vehicle, including work on car-specific systems. It is also evident that the driver/pilot must hold, at a minimum, a light/sport aircraft pilot licence.

These regulatory challenges present valuable opportunities. On one hand, they drive the development of innovative technical solutions. On the other, they open the door to creating an entirely new product by merging two well-established technologies: the car and the aircraft.

Safety is what helps new businesses grow and become widely accepted. We must avoid tragedies like the Titan submersible incident if we want new technologies and businesses to thrive safely. 

Author: , University of Limerick. This article first appeared on RTÉ's Brainstorm.