US President Donald Trump lamented on Tuesday that commercial aircraft are “becoming far too complex to fly,” amid the fallout from the crash of a Boeing airliner on Sunday.

“Pilots are no longer needed, but rather computer scientists from MIT,” Trump wrote on Twitter, after speculation that new automation technology could be behind the accident, which killed all 157 people on board.

Late on Tuesday India grounded the 737 MAX 8 aircraft, joining 15 countries including the UK, Australia, Singapore, Malaysia, although the US Federal Aviation Administration had not yet followed suit.

India’s Directorate General of Civil Aviation (DGCA) said the ban will remain in force until modifications and safety measures are undertaken to ensure the aircraft’s safe operation. Jet Airways and SpiceJet operate Boeing 737 Max aircraft in India – SpiceJet has 13 and Jet Airways five. While SpiceJet grounded its 13 aircraft after the DGCA order, Jet Airways planes were already grounded because of non-payment of lease rent.

Boeing shares plunged more than 6% on Tuesday, after recovering some of a near-12% drop on Monday.

Fueling concerns is the fact that the tragedy occurred within five months of a separate MAX crash in Indonesia, and in both cases the jets sported newer engines that required special automation systems intended to improve efficiency.

MIT Technology Review – perhaps in answer to Trump’s shout-out – summed up the technical concerns on Tuesday:

“According to a preliminary report released by the Indonesian air safety investigative agency, Lion Air 610 crashed because a faulty sensor erroneously reported that the airplane was stalling. The false report of a stall triggered an automated system that tried to point the aircraft’s nose down so that it could gain enough speed to fly safely. The pilots fought the automated system, trying to pull the nose back up. They lost.

“The 737 MAX has bigger engines than the original 737, which make it 14% more fuel-efficient than the previous generation. As the trade publication Air Current explains, the position and shape of the new engines changed how the aircraft handles, giving the nose a tendency to tip upward in some situations, which could cause the plane to stall. The new ‘maneuvering characteristics augmentation system’ was designed to counteract that tendency.”

“Did these more efficient engines – and the changes they necessitated to the airplane’s automation systems – compromise the aircraft’s safety? As sociologist Charles Perrow wrote in his classic 1984 book Normal Accidents, new air-safety technologies didn’t actually make airplanes safer. They just allowed airlines ‘to run greater risks in search of increased performance.’”

Nonetheless, Boeing said in a statement on Tuesday that it had “full confidence in the safety of the MAX. 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 them to ensure they have the information needed to have confidence in operating their fleets.”

The statement also stressed that the FAA “is not mandating any further action at this time, and based on the information currently available, we do not have any basis to issue new guidance to operators.”