Bug causes Boeing 737 cockpit screens to fail when it hits seven runways
The six cockpit screens in Boeing 737 NG passenger aircraft all turn off as the aircraft approach seven specific runways via the instrument approach procedure. The cause is a software bug.
It concerns seven runways; five are located in the United States, one is in Colombia and the last is in Guyana. The airworthiness directive of the American regulator FAA states that the screens in the cockpits of the aircraft in question will fail when they approach a runway with a heading of 270 degrees. The six screens, which include primary flight data, navigation data and engine properties, remain black until another runway is selected. The integrated standby flight display and the hud will continue to function if the six display units fail. The display units are the six central screens in the cockpit that are located directly in front of the pilots in the instrument panel.
The FAA says the bug occurs with the combination of a specific common display system software version of cockpit computers, Display Electronics Units, and certain flight management computer software versions. With this combination, the problem may occur at flight paths with the stated heading, but it does not always occur at this 270 degree heading; it is limited to the seven runways. These seven lanes have latitudes and longitudes that allow the software bug to occur. There were three incidents last year where this problem occurred, all of which involved a runway at an airport in Barrow, Alaska, USA.
The regulator does not provide full technical information about the problem, but does say that the erroneous Display Electronics Units software version has already been removed from a number of aircraft that have been serviced at the concerned airports. If not corrected, the problem could lead to an unsafe flight and landing, the FAA says. The Register speculates that the problem described by the FAA may mean that there is a “certain memory interaction” between different computers in the cockpit, leading to the information display on the screens stopping. The website has asked Boeing for a response, but the aircraft manufacturer has not responded.
There are a large number of aircraft where this problem can occur, namely the 737-600, -700, -700C, -800, -900, and -900ER. These are all different versions of the Boeing 737 Next Generation, which the aircraft maker has been making since 1997.
An instrument approach means that the aircraft uses the instruments during the approach, with the pilots following a signal that the airfield transmits. This allows pilots to position their aircraft in exactly the right line of the runway and descend with the correct glide path to arrive exactly on the runway. As a result, no direct view to the outside is required to land safely.