Boeing 737 MAX-9 Photo: Boeing

MIAMI – Last week was very important for Boeing; it received the go-ahead for the 737 MAX recertification by the FAA. After three days of a battery of tests, Steve Dickson (62) if the FAA declared the type ready for flight in Q3.

In order for the 737 MAX to receive the green light from the authorities, Boeing has so far mainly made changes to the flight control software MCAS, which corrects the position of the aircraft in flight and played a significant role in the accidents.

For example, the MCAS will only be activated by a software change in the future if it receives similar data from both angles of attack sensors.

In the crashes of Lion Air and Ethiopian Airlines, the system took action because it relied on incorrect data from a defective sensor.

However, the European Aviation Authority (Easa) continues to see a problem in the fact that the Boeing 737 MAX has only two of these sensors, whose data is used in many areas of flight control, not just the MCAS. Europeans fear that a sensor defect could lead to further problems.

Boeing 737 Max9

Does The 737 MAX Needs a Third Sensor?


An EASA spokeswoman told the Seattle Times that the Airbus A320 has three angle sensors. EASA wants Boeing to present a system “that corresponds to that in a way, but does not necessarily have to be a third sensor.”

Such an alternative could be an indication of the so-called Synthetic Airspeed, i.e. a calculated flight speed relative to the air. This system is installed as standard in the Long-haul Boeing 787.

Photo: Boeing

Confusing Warning Signals


EASA is also asking Boeing to make changes to the warnings in the cockpit of the 737 MAX. Investigations into the crashes suggest that the multitude of optical and acoustic warning signals overwhelmed and confused the pilots.

The Canadian Aviation Authority Transport Canada is also calling on Boeing to make improvements to the Stick Shaker. This is also a warning: if the aircraft is threatened with a flow breakdown, the pilot’s steering horn vibrates.

This was the case for six minutes in the Ethiopian accident. The Canadians want the manual of the jet to indicate how to disable the Stick Shaker – by means of a switch over the pilots’ heads – even before the 737 MAX is re-registered.

Boeing 737 Max8

Deadline: 2021


Two sources told the paper that the manufacturer would probably have to implement the changes by the time the largest Boeing 737 MAX 10 was certified.

This could take place around the end of 2021. The EASA spokeswoman said that a final timetable had not yet been agreed on due to Covid-19. However, once the adjustments have been completed and certified, the existing 737 MAX fleet would have to be retrofitted worldwide as soon as possible.

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