The European Aviation Safety Agency (EASA) has issued a public consultation on how to regulate futuristic air taxis that take off and land vertically.

In a proposed “special condition for small-category VTOL aircraft” published on its website on Monday, the agency said it has “received a number of requests for the type certification of vertical take-off and landing (VTOL) aircraft, which differ from conventional rotorcraft or fixed-wing aircraft.”

In plain English, this means air taxis like the one being worked on by Larry Page-backed Cora in New Zealand. EASA is now interested in licensing VTOL craft with up to five seats that are powered by “distributed lift/thrust units,” an example of which might be Lilium's improbable tail-fin-less ducted electric fan people-mover.

Ominously, the consultation document [PDF, 26 pages] warns that such aircraft “may not be able to perform an autorotation or a controlled glide in the event of a loss of lift/thrust.”

This is usually the death knell for unconventional aircraft. Certification, in aviation-speak, means a regulator compares a new design against a list of safety criteria. If the design doesn’t meet the criteria, it can’t be certified (and therefore it can’t be used to carry paying passengers or be sold as a ready-to-fly unit). If EASA is now seriously considering licensing these craft, it means that the EU regulator has accepted the increased level of risk that comes with the tech industry’s current plans for personal air taxis.

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Such concerns are acknowledged by EASA, which writes: “Once the Agency has gained more experience with this type of product, the Agency [EASA] will strive to transpose the special condition into a certification specification dedicated to these products.”

Designers must, however, take into account “critical malfunction of thrust/lift” and figure out how the human cargo will not be dropped like a stone to certain death. In conventional fixed-wing aircraft, loss of an engine means you start gliding back to terra firma under the pilot’s control. In a helicopter, autorotation happens: the main rotor keeps turning thanks to wind pressure, providing enough lift to make a controlled descent to a safe landing. But where the aircraft doesn’t have conventional wings or a main rotor, this poses problems.

In regulatory terms, EASA has copied its existing CS-23 spec for “normal, utility, aerobatic and commuter aeroplanes” (covering everything from the little Cessnas at your local flying club to twin-engined propeller aircraft used for training commercial pilots) and swapped a few words around to form its draft spec for VTOL air taxis.

Interestingly, the draft VTOL spec also includes the line: “The aircraft must be equipped with a [cockpit voice] recorder,” which could introduce a new level of GDPR headaches for potential makers and operators of future air taxis. ®