For air mobility believers, this FAA document is an overdue, but welcome, start

An aviation attorney offers reactions to the vertiport engineering brief

For years, artists have depicted the advanced air mobility revolution by showing us air taxis and cargo drones dashing among vertiports, some standalone and others integrated onto rooftops and airport properties. Now, FAA has issued an Airport Engineering Brief that begins to address the design considerations for vertiports.

As it created the brief, FAA collected information from those developing electric vertical takeoff and landing (eVTOL) aircraft. The agency cautions that it still does not have enough validated performance data to provide permanent standards and, therefore, takes a “conservative approach” in the 51-page “Engineering Brief 105” released in September.

The brief  establishes some historical context, noting that it issued an advisory on vertiport design back in 1991 based on anticipation that there would be “civil tiltrotors modeled after military tiltrotor technology,” but such aircraft were “never used commercially” and that advisory was canceled in 2010.

To gain some perspective on the new brief and FAA’s approach, I spoke with Ken Quinn, a former FAA chief counsel who is now a partner and aviation attorney at the London-based law firm Clyde & Co.

In general, Quinn says he was pleased FAA issued some guidance, because vertiport design standards are “critical building blocks” to accommodate the new aircraft. Unfortunately, he says, planning for infrastructure, including vertiports and their charging stations, “lags significantly behind” the investment in and development of eVTOLs.

The slow infrastructure planning may be part of the reason that investment in air taxi development has dropped off from record levels in 2020, Quinn says.

“When you have billions in investment around the world in eVTOL aircraft, a lot of folks have been wondering and scratching their heads saying, ‘Where are they going to land? Where will they get power?’” Quinn says.

The report begins to address that problem, but not exactly in the manner Quinn would like to see. “A lot of their standards here are very prescriptive,” he says.

For instance, the brief prescribes the dimensions for the protected final approach and takeoff areas (FATOs) and touchdown and lift off areas (TLOFs), defining them with formulas based on the largest aircraft intended for the vertiport, Quinn notes. The size of the FATO must be twice that of the aircraft diameter, which FAA says would be the smallest circle enclosing the aircraft projections on a horizontal plane, while the aircraft is in the takeoff or landing configuration, with rotors or propellers turning.

“Ultimately, you want to see the FAA and other civil aviation authorities building more flexibility to allow performance-based standards,” Quinn says.

Also, outwash of air currents from rotors and propellers must be considered in vertiport design, according to the FAA brief, but data on such conditions is severely limited, Quinn notes.

“You don’t have the length and wash of large helicopter blades, but you have far more rotors typically, which generally can increase safety of the aircraft but may have unpredictable effects on outwash or downdraft,” he says.

Quinn applauds FAA for including some reference to rooftop locations of vertiports, but he says much more consideration must be given to these urban landing spots.

“The goal is not necessarily to fly to an airport, but to streamline congested corridors, where they can land on parking garages, rooftops and parking lots” equipped with vertiports, Quinn says. “The future of air mobility does not depend on landing at the airport, it’s about having local landing pads with charging stations.”

Regarding those kinds of locations, the brief contains several bullet points cautioning vertiport developers that penthouses, cooling towers, and exhaust vents must not interfere with vertiport approach and takeoff areas.

Also provided are broad recommendations for security at vertiports. Quinn says FAA and the Transportation Security Administration must accelerate work on such standards if the public is going to accept widespread air taxi and cargo drone operations overhead, especially in dense urban areas.

“Federal security folks at TSA and in defense sectors are understandably concerned about AAM operations,” Quinn says. “They don’t want remotely piloted aircraft being able to fly around when they don’t know what’s on board, meaning not just people but potentially hazardous or other destructive devices.”

The brief also addresses fire safety, including the storage of lithium batteries. Quinn says he believes such fire safety standards are well understood and are not an obstacle

Ultimately, the industry and the regulators must move ahead more quickly with infrastructure planning, Quinn advises.

“Unless infrastructure catches up with aircraft design, this will never become reality,” he says.

Related Topics

Advanced air mobility

For air mobility believers, this FAA document is an overdue, but welcome, start