When traveling by air, many airlines recommend that passengers check in at the airport 2 hours in advance, and some international flights even recommend that passengers check in 3 hours in advance. Once you miss the check-in time, even if you have arrived at the airport and are confident of getting to the cabin door before the plane takes off, the airport will not be "accommodating".
China Southern Airlines boarding prompt information, the picture is taken from the official website of China Southern Airlines
This is not because the airport or airline is unkind, but because there is a lot of preparation work before the plane takes off, some of which can only be carried out after the number of passengers and luggage is determined.
Important "manifest"
Although pilots and flight attendants have different preparations before takeoff, they all point to the same important thing - the manifest.
The pilot needs to input the data on the manifest into the computer on the aircraft, and must have the manifest before he can apply to the tower for takeoff, and then line up to take off according to the instructions.
There is a key step in the process of making a manifest,The airline or the stowage department of the airport is required, based on the aircraft model, flight fuel consumption, and number of passengers.(weight),Baggage weight and other information can be used to calculate the aircraft's load balance to keep the aircraft's center of gravity within a safe range.
Therefore, this step must be carried out after the weight of the passenger and luggage is completely determined. If passengers continue to board the plane, the passenger weight and baggage weight will change, and the aircraft's load balance will need to be recalculated.
Therefore, check-in is not allowed 30 minutes (or even longer) before the flight takes off, otherwise it will delay the journey of other passengers.
Load balance and center of gravity that cannot be ignored
Although passengers have little sense of "load balance" and "center of gravity" when flying, they are very important to the safety of the flight.
For example, the crash of China Northern Airlines Flight 6136 (also known as the May 7th crash) in 2002 was related to the change in the aircraft's center of gravity.
The cause of this air crash was arson.After a fire breaks out in the cabin of an airplane, it can still fly a certain distance. In this emergency situation, the pilot decided to avoid densely populated urban areas and fly to the sea to make an emergency landing to avoid casualties on the ground. However, after the cabin caught fire, the passengers instinctively rushed to the front of the cabin where the fire had not spread. This caused the plane's center of gravity to suddenly shift forward, and the plane crashed head-first into the sea.
Additionally, in 2013, National Airlines Flight 102, because during the flight,The cargo in the cargo hold was not securely fixed and moved, causing the center of gravity of the entire aircraft to shift backwards, resulting in a tragic crash and fatalities.
According to a 2016 study, 77% of flight accidents are related to the aircraft's center of gravity exceeding the safe range, and 57% of these accidents will have fatal consequences.
Since load balance and center of gravity are so important to flight safety, it is very necessary to allow sufficient time for staff to make calculations, reasonably arrange baggage, fuel volume, and place counterweight loads.
By the way, when purchasing a ticket, if the plane is not full, the airline will not allow passengers to choose their seats completely freely to avoid the situation where all passengers choose a certain side of the plane, or are concentrated in the front or rear of the plane.
andDuring the flight, even if the seat in front is empty, the crew usually will not let passengers change seats at will.
For example, in 2015, there was a case where a passenger insisted on changing to a seat near the front instead of seated according to the seat on the ticket, causing other passengers to follow suit, which ultimately affected the load balance of the aircraft.
Passengers don’t weigh themselves, so how do they know their weight?
If weight balance is so important, how do the crew know the weight of us and our luggage? After all, when boarding the plane, only checked baggage will go through the scale, and people and carry-on baggage will not be weighed.
The answer is also very simple, just rely on estimation.Although load balance and center of gravity are important, they do not require exactness.
According to the classification in the "Aircraft Weight and Balance Control Regulations" of the Civil Aviation Administration of China, most of the flights we take are "large cabin aircraft".
For this type of aircraft, the "standard average weight" of passengers and luggage can be used for estimation. Because the larger the aircraft, the more passengers there are, and the more accurate the estimate using the standard average weight will be.
Classification table of aircraft types in the "Aircraft Weight and Balance Control Regulations"
For example, the standard average weight for an adult is 75 kilograms, which includes clothing and hand luggage. The average weight is 38 kg for children and 10 kg for infants.
Provisions on standard average passenger weight in the "Aircraft Weight and Balance Control Regulations"
Of course, the "standard average passenger weight" used in my country may not be applicable to other countries and regions. For example, according to the Centers for Disease Control and Prevention (CDC), the average weight of adult men in the United States is 90.63 kilograms (199.8 pounds) and women 77.47 kilograms (170.8 pounds). Add in the weight of clothing and luggage, and the weight is well over 75 kilograms.
in addition,Some airlines have restrictions on the size and weight of carry-on luggage, on the one hand, of course, it is to ensure that the luggage can be placed in the luggage rack in the cabin. In addition, it is also to prevent passengers from carrying too much luggage and affecting the weight estimate.
last minute limit
Although planes close for check-in 30 minutes to an hour before departure, some special circumstances may arise.
For example, some passengers who have completed check-in may be so busy browsing the duty-free shops at the airport that they do not arrive at the boarding gate before the aircraft door closes.
When the boarding gate is about to close, the airport will announce the names of these passengers as a reminder. But if they still don't arrive after the announcement, the captain has the right to issue an order to take off directly. After all, it is impossible to make the entire plane wait.
In this case, the aircraft does not necessarily need to recalculate the load balance.
There's a term called "last-minute fixes," which refers toAfter the manifest is made and before departure, the flight can fine-tune the load without having to make a new manifest.Including adjustments to fuel weight, crew and passenger personnel, cargo adjustments, etc.
This adjustment only needs to be filled in the remarks column of the manifest, and the captain and the relevant personnel responsible for load and balance must confirm, verify and sign.
For example, the picture below is a "last-minute correction" form on an airline's manifest. The values that can be adjusted in the last minute correction are related to the maximum fuel-free weight, maximum take-off weight, and maximum landing weight.
The "last minute corrections" section of an airline's manifest
This manifest is for the A320-200 aircraft, which can be adjusted for up to 6 passengers or 500kg payload. If too many people or loads are changed, the load balance still needs to be recalculated and the manifest remade. This will undoubtedly delay other passengers on the flight, so don’t forget to board the plane in time after checking in.
In addition, during the communication process with the pilot, there is also a noteworthy detail. If all personnel are present, the cargo is loaded, the aircraft door is closed, and there are no restrictions on the route, you can apply for early takeoff. Although the premise is a bit restrictive, maybe you can catch up once!
Finally, I would like to remind you again that when traveling by plane, it is best to arrive at the airport as early as possible, and pay attention to the boarding time after check-in. This not only ensures a smooth trip, but also respects other passengers and crew members.