European safety authorities are intending to formalise the concept of sterile cockpit procedures through a revision of air operations regulations.
Sterile cockpit procedures are aimed at ensuring the pilots focus only on aircraft operations at crucial points during the flight when distractions - such as extraneous conversations, non-essential cabin crew calls and public address - are most likely to create problems.
In a notice detailing its proposal the European Aviation Safety Agency says this concept does not feature in current refinements to operational rules.
"When flight crew are not concentrating their attention on the conduct of flight activities, or are involved in actions that are not related to flying, critical information can be missed or misinterpreted," it states. "The situation can deteriorate very rapidly."
Investigation into the fatal Spanair Boeing MD-82 crash at Madrid - attributed to the pilots' failure to deploy flaps before take-off - highlighted the value of a sterile cockpit and the definition of critical phases of flight. EASA cites the August 2008 accident in its reasoning for the revision.
EASA also points out that the US Federal Aviation Administration enacted a sterile cockpit rule more than 30 years ago.
It says that a major aim of the change is to enhance runway safety through improving operational procedures and best practices for taxiing. The new rule takes into account not only the FAA regulation but also proposals from a Joint Aviation Authorities steering group, ICAO information and recommendations from a European runway-incursion action plan.
EASA considered four options for the new rule, of which two involved specific rulemaking action for sterile cockpit procedures for all critical phases of flight, and for flight below 10,000ft.
These two options differed, however, in their treatment of taxiing: one defining it as a safety-critical activity and the other defining it as a critical phase of flight.
EASA says the former option is preferable because the "additional burden" of defining taxiing as a critical phase of flight would be "significantly higher" in terms of costs, while the reduction in risk would be "only slightly lower".
This is because a change in definition would require all cabin crew to be seated during taxi and, in turn, would increase turnaround times because many cabin procedures would then have to be carried out before pushback.
EASA is inviting comment on the proposal until 11 October.