Note that the article only states that the ground crew found the cover floating in the water. It didn't actually say the aircraft took off with it on. It may b

Note that the article only states that the ground crew found the cover floating in the water. It didn't actually say the aircraft took off with it on. It may be, eg, that it had been taken off properly but got (or was left) loose on the flight deck and blew up into the intake of the jet as it was taking off. Something for the ground crew to fix, for sure, but not necessarily a catastrophic failure of standard checking procedures.