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On a recent flight from Washington, DC to Toronto, the pilot gave very specific directions to rebalance the plane (a Dash-8 IIRC), something like "someone needs to move to seat 11E."

How did he know that putting someone in seat 11E would balance the plane properly? Does the plane weigh itself or is there a computer model somewhere that tells him what to do? Or would an experienced pilot be able to look at the seat chart and know what to do?

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  • $\begingroup$ Related: Are passengers really not allowed to change seats before take-off due to weight and balance? $\endgroup$ – fooot♦ May 8 '16 at 0:38
  • $\begingroup$ Related: How does a commercial airliner measure its weight/mass? This may not answer exactly your question, but will provide what is the process. $\endgroup$ – mins May 8 '16 at 0:38
  • $\begingroup$ Typically an experienced pilot flying a commuter-class aircraft where he can look back and see all of the seats will know if the aircraft is within balance and which seats to fill to balance if it is not. However, a weight & balance must still be calculated and made available on the ground. I stopped flying commuters in the late 1980s, but even then we used programmable calculators to do the calculation. Manual work sheets were also available. $\endgroup$ – Terry May 8 '16 at 2:00
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    $\begingroup$ You say a small plane with a seat 11E? ... I do not think this "small plane" term means what you think it means ;) $\endgroup$ – Ryan Mortensen May 8 '16 at 5:21
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    $\begingroup$ @MortensenAviation +1 for The Princess Bride reference! $\endgroup$ – FreeMan May 9 '16 at 13:11
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Depending on the airline, and the size of the aircraft, the Weight and Balance calculations for each flight are either done by the pilots, or by the Flight Operations, Load Department.

If it is done by the pilots, they will receive the loading information which contains the weight and location of all passengers, cargo, and fuel. They then calculate manually, or by using software, the exact center of gravity.

If done by the Load Department, the center of gravity information will be communicated by radio or ACARS datalink.

It is not unusual to require a last minute seating or cargo change in order to ensure the aircraft is within the proper center of gravity limits for takeoff.

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  • $\begingroup$ I think they use an average accepted adult-human weight, right? In reality, in airlines, they don't know anything "exactly" weight-wise. Maybe, it's different for regionals or corps. $\endgroup$ – Ryan Mortensen May 8 '16 at 5:23
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    $\begingroup$ Depends on the opspecs for the carrier. The carriers I worked for required actual weights for EVERYTHING. This means weighing each box (up to 5000lbs of UPS next day freight) and weighting passengers. If a passenger refused to consent to an actual weight check we could ask their weight and then add 10lbs for use in our W&B calculations. Most planes with 19 or more seats -or- scheduled passenger carriers use the "FAA standard" weight. There is a summer and winter "standard" to account for bulkier winter clothes. $\endgroup$ – acpilot May 8 '16 at 6:25
  • $\begingroup$ See en.wikipedia.org/wiki/Air_Midwest_Flight_5481 for details of how the FAA standard weight gets updated... $\endgroup$ – DJohnM May 8 '16 at 7:20

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