European safety regulators are seeking to develop flight-time limitations tailored to the specific requirements of air taxi and emergency medical service operations.

The proposal is laid out in a newly-published opinion from the European Union Aviation Safety Agency (EASA).

It states that rules on flight-time limitations – known as ‘subpart Q’ – originally prioritised scheduled and charter airline services.

While these rules have been applied to the on-demand air taxi and medical sectors, as well as single-pilot operations, there are “obvious differences”, says EASA, including their typical use of small executive jets.

“Forcing aircrew on [these flights] to apply rules that were developed for a multi-crew operational environment may, in fact, impact the safety of the flights,” says the EASA opinion. “One size does not fit all when it comes to air safety.”

Subpart Q also has “some fundamental gaps” when applied to the on-demand sectors, it adds, such as an absence of maximum daily flight-duty periods – these are sometimes regulated by national rules, but not in all cases.

“This means that there is no uniform level of safety, and no level playing field in this area,” the opinion says.

EASA says it wants to bring regulation of fatigue in air taxi and emergency medical operations to a level “commensurate” with the most up-to-date scientific principles and best practices – while maintaining a “degree of flexibility” proportionate to risk.

These sectors present particular challenges to fatigue management, owing to their specific characteristics.

They tend to involve short notice, long standby periods, frequent changes of schedule or route, time-zone crossings, and wait periods between outbound and inbound flights. Medical response might require multiple flights and, depending on the scenario, a need to extend beyond planned duty times.

EASA says it has used the latest scientific knowledge about fatigue to develop its opinion, but adds that it combines this with good operational practices and modern fatigue-risk management approaches. The tailored rules include “targeted” mitigation measures to reflect “operational realities”, it adds.

The proposals – which are intended to apply from September 2028 – follow a consultation which attracted nearly 1,500 responses.

EASA says that, based on the comments received, it is excluding helicopter-based emergency medical services from the rulemaking task to focus on fixed-wing aircraft.

Although “many” commentators claimed changes were not justified – because current rules provide adequate risk-mitigation – EASA says analysis of 1,600 accidents and incidents confirm that fatigue remains an “important risk factor”, and adds that a direct link between fatigue and safety events is “very often not evident”.