This critical software bug turns the Bombardier airplane to go the wrong way i.e turn right instead of left
This is one critical bug that can cause fatalities. A team of researchers have discovered a highly critical vulnerability in the Pro-Line 4 FMC software being used in Bombardier airplanes.
The vulnerability was first discovered by Nav Canada in 2017 on a Bombardier CRJ-200. The researchers discovered that this particular and unique bug makes the aircraft to switch to the wrong way, in short, this bug turns the airplane to right instead of left if pilots regulate the pre-set height limit. Soon after the incident, this particular but was reported to the Bombardier and FAA but it seems that the bug has still not been fixed.
This vulnerability comes into play when the Bombardier aircraft is flying through extremely cold conditions and the aircraft’s pilots set the plane on auto-pilot. The flaw happens when Bombardier airplane pilots use temperature compensation function. For the uninitiated, In general, temperature compensation is a method used to adjust a system’s performance to compensate for effects caused by changes in temperature. It is used by airplane pilots to compensate for very cold climates. The bug is triggered when the temperature compensation is used and the airplane is in autopilot making it go in the wrong way, i.e. turn right instead of left or vice-versa.
The pilots who have experienced the bug say that the airplane just turns the wrong way as if it was heeding the published missed approach. A published missed approach is the one published, sometimes however the local ATC will give you their own missed approach instructions and you will need to follow those.
The FAA docket on this bug says that this can because of the design error as the software imagines the flight division has shifted.
According to the FAA, the bug can be fixed by disabling the FMS automatic features in the aircraft’s configuration strapping unit (CSU) and reviewing the airplane flight manual (AFM) reservations segment. In layman speak, it means disabling the FMS automatic feature and autopilot in the pilot’s console.
However, Rockwell Collins opposed the FAA’s opinion to disable its Pro-Line 4 FMC software. According to Rockwell Collins, the chances of the bug effecting are very remote. It is also not known whether the bug affects only Bombardier CRJ-200 or other Bombardier airplanes having the CRJ FMS 4.x software.
You can read the Bombardier’s confidential report about the FMC software here(PDF).