Plane crashes involving large passenger jets are such a rarity in the 21st century. Growing up, it seemed to happen once or twice a year.

But in the span of six months, two Boeing 737 Max passenger jets have crashed. This past weekend, a crash in Ethiopia’s capital killed all 157 on board. A new Lion Air Boeing 737 MAX 8 flight went down over the Java Sea last October, killing 189 people.

Both crashes happened just over takeoff.

Some airlines and national aviation authorities have grounded their 737 MAX fleet in the wake of the crash of Ethiopian Airlines flight 302. Thus far, Chinese and Indonesian regulators along with Ethiopian Airlines, Aeromexico, Cayman Airways, Comair, GOL, MIAT Mongolian Airlines, and Royal Air Maroc have temporarily halted 737 MAX flights. Same with
Icelandair, Ireland, Norwegian, and TUI. France, Germany, Britain, Australia, Singapore, Malaysia and Oman joined China and Indonesia in suspending all use of the plane.

When the UK announced a ban on all Boeing 737 MAX jets this morning, some of the MAX 8 jets were already en route to land at UK airports or travel through UK airspaces.

At least least two of those flights now appear to be turning back.

American Airlines operates 24 Max 8 jets, and Southwest Airlines operates the largest U.S. fleet of these planes, with 34. Both airlines expressed confidence in the safety of the aircraft and their crews

Even Trump weighed in:

It’s not that complex. The concern after the Lion Air crash was that erroneous readings from poorly maintained sensors in the nose of the plane might have fooled the automatic systems into detecting that the plane was traveling sharply upward and in danger of stalling, when it was actually in level flight. The automatic systems may then have forced the nose down significantly, sending the plane into a steep dive into the ocean.

Better education of the pilots about the problem with automation during takeoff would require that the pilots simply turn it off. It’s not known yet if the pilots in these cases were aware of the issue.

Share prices of Boeing, a major component of the Dow Jones industrial average, fell 5.7 percent in early trading today, following a similar decline yesterday. on worries about the spreading impact of the Max 8 crash in Ethiopia and the prognosis for future sales of the plane.