American Airlines put the Boeing 737 Max back into passenger service in the US on Tuesday when it operated a 737 Max 8 between Miami International Airport and New York’s LaGuardia Airport. The flight, which landed in New York at 1:12 p.m. ET after flying almost three hours, comes 21 months after the Max was grounded over a pair of crashes in 2018 and 2019 that killed 346 people. The American flight follows the Federal Aviation Administration’s decision last month to clear the beleaguered aircraft to return to the sky. As part of the decision the agency has ordered Boeing and airlines to make repairs to a flight control system blamed for both crashes and increase pilot training. Other reports have identified additional concerns with the airliner’s flight control computer, wiring and engines. Editors’ top picks Subscribe to CNET Now for the day’s most interesting reviews, news stories and videos. The Max has also resumed carrying passengers in Brazil, and other US airlines that fly the Max are planning to add the Max back into their fleets by the second quarter of next year. Aviation safety agencies in Canada and the European Union are still conducting their own reviews of the plane. Until those are completed, the 737 Max will remain grounded in…