New York’s LaGuardia airport was so busy last Sunday before an Air Canada (AC.TO) jet collided with a fire truck that additional staff should have been brought in to help, several current and former US air traffic controllers said. Weather-related delays resulted in 70 commercial flights taking off or landing at the airport between 10 p.m. and 11:37 p.m., when the Air Canada Express CRJ-900 regional jet crashed, killing both pilots.