Boeing has issued changes to control systems linked to two fatal crashes of its 737 Max planes in the past five months.
However, the U.S aircraft manufacturing company did not give go ahead to operators to resume flight with the aircraft which were grounded by many countries’ aviation authorities following the fatal crashes.
A news report by BBC.Com indicated that investigators had not yet determined the cause of the accidents.
According to the report, aAs part of the upgrade, Boeing will install an extra warning system on all 737 Max aircraft, which was previously an optional safety feature.
Neither of the planes, operated by Lion Air in Indonesia and Ethiopian Airlines, that were involved in the fatal crashes carried the alert systems, which are designed to warn pilots when sensors produce contradictory readings.
Boeing said that airlines would no longer be charged extra for that safety system to be installed.
In addition, Boeing in furtherance of its efforts to enhance the aircraft’s safety system, has also issued an upgrade to the Manoeuvring Characteristics Augmentation System, better known as MCAS, software that has been linked to the crashes.
The MCAS is software designed to help prevent the 737 Max 8 from stalling. It reacts when sensors in the nose of the aircraft show the jet is climbing at too steep an angle, which can cause a plane to stall.
However, an investigation of the Lion Air flight last year suggested the system malfunctioned, and forced the plane’s nose down more than 20 times before it crashed into the sea killing all 189 passengers and crew.
The US Federal Aviation Administration (FAA) says there are similarities between that crash and the Ethiopian accident on 10 March.
Boeing has redesigned the software so that it will disable MCAS if it receives conflicting data from its sensors.
In a briefing to reporters, Boeing said that the upgrades were not an admission that the system had caused the crashes.