MIAMI – U.S. airlines have decided to give skeptical passengers the possibility to change their flights free of charge if their flights are operated with the Boeing 737 MAX.

As flight certification tests of the infamous 737 MAX were carried out in Seattle, U.S. airlines are preparing to welcome back the Boeing medium-range jet into their fleets.

The Boeing 737 MAX was involved in two deadly accidents due to a faulty Fly-By-Wire system known as Maneuvering Characteristics Augmentation System (MCAS).

American Airlunes 737 MAXs grounded in the desert.

Comments from United Airlines

While U.S. carriers have not yet announced policies related to the return of service of the MAX, in a statement this week to The Times, a United Airlines (UA) spokeswoman said:

“United Airlines will be transparently communicating in advance with our customers who are booked to fly on a MAX aircraft, giving them the possibility to rebook to a different flight those who do not want to fly on a Max at no charge.”

MCAS Overview: Boeing.

What is the Maneuvering Characteristics Augmentation System

The Maneuvering Characteristics Augmentation System (MCAS) was designed and certified for the 737 MAX to enhance the pitch stability of the airplane so that it feels and flies like other Boeing 737.

MCAS is designed to activate in manual flight, with the airplane’s flaps up, at an elevated Angle of Attack (AOA).

Boeing states on its website that it has developed an MCAS software update to provide additional layers of protection if the AOA sensors provide erroneous data.