UPDATE: Boeing Facing Pressure To Ground 737 Max 8s For Safety

According to Boeing, the update is "designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training."

The announcement came as airlines and countries around the world are grounding the plane after two 737 Max 8s crashed mysteriously within six months. Both crashes occurred just minutes after takeoff with experienced pilots at the controls. 

U.S. Senators Dianne Feinstein, (D-California) and Richard Bluemthal, (D-Connecticut), have called on FAA Acting Administrator Daniel Ellwell to stop all 737 Max flights "until their safe use has been confirmed."

"Continuing to fly an airplane that has been involved in two fatal crashes within just six months presents an unnecessary, potentially life-life-threatening risk to the traveling public," according to a letter from Feinstein. 

Two years after Boeing launched its new 737 Max, which the aviation giant touted as the fastest-selling aircraft in company history, two of the single aisle jets mysteriously crashed minutes after takeoff, just six months apart.

On Monday, investigators found the black boxes, that is, the digital flight data recorder and the cockpit voice recorder from Ethiopian Airlines Flight ET302. The plane crashed six minutes after taking off from Addis Ababa, killing all 157 people on board.

In October, a Lion Air flight crashed over the Java Sea 13 minutes after takeoff. All 189 people on board that 737 Max 8 died as well.

Sunday's crash prompted countries and airlines across the world to suspend use of the planes. 

So far, 15 countries have suspended flights of the 737 Max 8 into or out of their airspace. And the list is growing. On Tuesday afternoon, the European Union Aviation Safety Agency banned 737 Max flights after Austria, Britain, Ireland and France announced similar bans. Australian authorities also announced a temporary ban, which will affect two foreign airlines operating in that country, SilkAir and Fiji Airways. Those airlines use the planes for flights to from the country. There are no Australian airlines with 737 Max 8s in their fleets.  

In Brazil, Gol Airlines grounded all 121 of its 737 Max 8s. The company noted it has made nearly 3,000 flights using the planes without incident.

Many airlines are following suit and have grounded the planes. Currently, Boeing has no plans to recall the plane or issue new recommendations to customers or pilots.

After the Lion Air tragedy, Boeing issued a service bulletin for Max 8 and Max 9 pilots. The bulletin warned pilots that the jet's AOA sensor can produce faulty indications, causing the jet to dive to gain airspeed, which the system mistakenly reads as too slow.

Following both crashes, officials said that each plane experienced fluctuations in altitude. Graphs of the vertical flight paths are eerily similar, with both flights crashing in a very steep dive.

Aviation officials said that there is no evidence right now that whatever caused the two crashes are linked, though many observers warn that the similarities between the crashes suggest a common cause. A final determination is two to three years away, but information from the flight recorders should be available in a few weeks.

In the meantime, Ethiopian Airlines and Cayman Airways have grounded the Boeing 737 Max 8s in their fleets. As of Monday morning, Chinese aviation officials ordered all of China's Boeing 737 Max 8s grounded.

American Airlines and Southwest Airlines, which has 24 and 34 of the 737 Max 8s in their fleets, respectively, will continue to fly the planes. Spokespeople from both airlines have said their companies have no plans to ground those planes at this time.

According to a statement from Boeing: 

"We understand that regulatory agencies and customers have made decisions that they believe are most appropriate for their home markets. We'll continue to engage with all of them to ensure they have all the information they need to have the confidence they need safely continue to operate their fleets or return them to service."