The investigative branch of the U.K.'s Dept. of Transport issued four recommendations to Airbus after the crew of an Airbus A319 reported that the plane's flight and navigation displays had failed.

Investigators with the Air Accidents Investigation Branch (AAIB) noted the plane, registered to British Airways, lost information on a number of displays as it approached a flight level of 20,000 feet on a flight from London to Budapest last October.

Both the pilot and co-pilot lost primary flight and navigation displays, leaving the lower Electronic Aircraft Centralized Monitor (ECAM) as the only source of information. The crew also lost autopilot, autothrust, intercom and most of the flight deck lighting.

AAIB said most of the systems were restored after about 90 seconds during which the crew followed ECAM procedures.

The limitations of how much information the lower ECAM is capable of displaying during a system failure triggered AAIB's concern.

The crew must clear messages listed on the ECAM in order until all items have been removed. In this particular incident, AAIB said the ECAM action to restore power to the displays was the ninth or 10th item on the list. AAIB suggest Airbus consider whether the priority of items listed on the ECAM should be changed.

Airbus also should review the A320 family master minimum equipment list, AAIB said, since the current list notes five of the six display units must function, including the upper ECAM. As a result, the plane can be dispatched if the lower ECAM is not working. "On this occasion," AAIB said, "the ECAM lower display was the only one left available."

Other recommendations made by AAIB to Airbus include ensuring the standby artificial horizon on A320 planes has a dual power supply and revising the plane's flight crew manual to ensure they contain the correct information about power sources.

AAIB also said it was aware of five previous incidents involving failures that caused loss of primary flight and navigation displays, noting that the reason for the losses "has not been fully explained in any of these cases."