During my recent flight, the captain announced that he took excess fuel and wanted the weight distribution adjusted in an almost full flight. A passenger was kicked out and the flight attended sent a couple of passengers back and brough one forward. Years back, in a near empty big airliner (only 6 passengers!), we were all asked to go to the back of the plane.

My questions:
1) Is the "weight distribution/balance" arbitarily determined or is there a gadget in the cockpit that indicates plane weight imbalance?
2) In an otherwise full plane carrying over 60 people, does the "re-distribution" of a couple of people make a difference?
3) Has there been any incidence where imbalance played a role in any accident?

This thread may help:

Balancing aircraft (seating)

It's calculated based on the weight of the load at different locations. If the CG (center of gravity) is too far forward, moving load (passengers) from front to back will help.

If you are just a tad bit forward of the CG envelope, moving a couple of pax may be all it takes.

I bet you never thought of yourself as human ballast, did you?

Yes. Often it is not the only factor causing the accident by itself, but one factor in a chain. The January 2003 US Airways Express in Charlotte was one.

This thread reminds me of the dirty look I got from a pilot on a very small plane.

I was taking pictures out of my window and then leaning across the aisle to take them out the other window.

I guess I was rocking the plane and he noticed. I'm only 5'11" and 180lbs though.

No gadget in the cockpit strangely enough. Weight and balance is calculated on ground prior to departure and the settings affect everything from fuel uplifted to takeoff thrust to the angle of attack in cruise. Most airlines use computer programs for "load control" but there are still some that use old manual loadsheets on a regular basis.

Absolutely. Each passenger weighs about 80kgs on paper (exact figure may vary depending on season, gender, etc..). This can be almost 2% of the total movable payload on board a 60 seater aircraft. When you consider the influence that the moment arm generated by this plays, even a single person can make a difference.

Sadly, many, although the imbalance itself is usually caused due to loading error or data input oversight. The most notable one is probably the MK Airlines 747 freighter crash in Halifax back in 2004. The Air Midwest / US Airways Express B1900 in Charlotte in 2003 was another.

When the Jet Blue A320 with the nose wheel stuck perpendicular to the position it should be for landing was flying around before landing, they moved the passengers and carry on baggage to the back of the plane before landing.

On my last rj flight the FA counted the fiurst 4rows and I guess it was too many for the overall capacity so she had to rebalance to the back. I guess its just basic counting of pax within certain rows.

Thanks for answering but another question-this question is unrelated and may appear strange and silly.
Almost as a rule baggage handlers appear to load the luggage on the "wrong" side (of the luggage, for example with the pocket side of a suitcase down and the flat side up). After seeing this a few times, I don't leave anything crushable, sqeezable, breakable, in suitcase pockets. I have seen at times, even when the suitcase seems to be on its flat side, handlers turning it otherway.
Is there a logical reason or just the "revenge of the baggage handlers"?

Recently had a return flight from SYD-SFO cancelled due to equip. Had to stay one extra day and was happily put on same flight 24 hrs later. Res was in C class (UAL).

After boarding for the return flight, there was a delay to manage the load. All passengers in the second section of the C class seats on our 777 were reassigned to seats on the perimeter of the plane. A number of families were separated. Once accomplished, we took off with all 16 center seats empty.

Once meal service was complete and lights turned down, primarily all of those 16 seats were occupied by FA's who slept/lounged until just before lights turned on for pre-landing services at which time they all disappeared.

Strange?