Passengers who reach boarding gates after the aircraft door is closed wonder why they were not allowed to board. After all (as the perception is), it would not take long for a mere door to be opened to let a person enter the plane. But boarding an aircraft is not like boarding a train: Aircraft doors close by protocol about 15 minutes before departure. And there are good reasons for this:
A weighty matter
It’s all about weight distribution
When the captain and co-pilot walk into the aircraft, a flight dispatcher gives them the expected weight on board:
-Fuel weight + cargo weight + passengers’ weight
-Information on the total number of passengers is not given at the time
-The pilot starts feeding the weight data into the flight management computer. Among other things, it calculates various speeds, such as different speeds for take-off and approach
-The technical log comes in and it gives more weight details, such as tons of fuel and litres of oil in engines