European safety regulators are shying away from proposals to require alternative power supply for flight-data recorders, to reduce the risk of information being lost as a result of an accident.

The European Union Aviation Safety Agency had previously put forward proposals to require back-up power for cockpit-voice recorders, but deferred the issue of a similar measure for flight-data recorders.

EASA has revisited the suggestion in a new notice of proposed amendment. It acknowledges that unavailability of recorder data can potentially hinder investigators’ work in identifying the cause of an accident.

But while several safety investigations have recommended alternate power to prevent interruption of flight-data recordings, EASA has concluded that the proposal would be complex and offer little safety improvement.

At least nine occurrences since 1996 have involved flight-data recorders on large transport aircraft stopping as a result of electrical power loss – with the interruptions lasting from less than 60s to around 19min.

“Overall, the absence of [flight-data recorder information] for a certain period of time has not prevented the identification of the root causes of these occurrences,” says EASA.

As a result, it argues, the risk to safety from failure to establish the circumstances of each incident “can be considered low”. Investigators would still have access to information from cockpit-voice recorders, it adds, following the earlier proposal for back-up power.

EASA says the issue is complicated because an alternate power supply for the flight-data recorder would have to power, for about 10min, various elements in addition to the recorder itself.

These include flight-data acquisition units – which can have power consumptions higher than the recorder – and potentially dedicated sensors, converters, busses and switches.

Powering all these components would involve consuming more energy than current independent recorder supplies are capable of delivering, which would involve expending a “non-negligible” portion of the emergency battery power.

EASA says there is “not enough” safety benefit to be gained from implementing an alternate power source for flight-data recorders to justify the economic impact of a mandate.