UA1KPHL

Strange thing happened Tuesday from phl to sfo. I was seated first few rows and before takeoff we were told to move back to at least row 12 cause nose as heavy. I got the seat free due to status but lady next to me said she paid $120 bucks for that seat.. I have had this happen many times on small planes but its a first for Airbus A319.

mahasamatman

It can happen on any aircraft, though it is much more common on smaller planes. I would guess it had to do with the cargo distribution.

kenn0223

How full was the plane?

Typically you're allowed to move back after takeoff, was this not the case?

With light passenger load it could be that there was just a little bit too much cargo in the front compartment and it was easier to trim with a passenger or two than to shift cargo around.

TA

One question that has always puzzled me about this kind of weight situation:

If an airplane has the control capabilities / load balance margins of operation when fully loaded, why does it "need" to be rebalanced when not even full?

Can the trim surfaces not compensate? I know it wouldn't be ideal, but I would think it is hardly an issue of not being able to fly the plane within weight balance limits if the passengers were not moved.

tlawrence85

Imagine a very simple airplane that can carry up to 2000 lbs of payload. When fully loaded, 1000 lbs of payload would sit fore of the wing, and 1000 lbs of payload would sit aft of the wing. For simplicity, assume they're equidistant from the point where lift acts on the wing. The point where lift acts on the wing can be considered the pivot point for balance, and since each 1000 lbs load is equidistant from that point, the plane is perfectly balanced (imagine a see saw with 2 equal loads).

Now, imagine this plane isn't fully loaded. Instead, the plane is only carrying 1000 lbs of load, but all 1000 lbs are fore of the wing. This plane is now extremely unbalanced and will tend to pitch down. So, even though the plane is not even close to full, the resulting forces could be more than the trim surfaces can compensate for.

Often1

W&B affects anything that flies. It's simply a less common problem requiring on-the-spot action, the larger the aircraft.

valor155

She should ask for and get a refund.

mgcsinc

Indeed. And UA better not pull this all-E+-seats-are-created-equal crap. They charge different amounts for the different seats.

mahasamatman

Every aircraft has a "weight and balance envelope". Having a center of gravity outside the envelope is not just a violation of FARs, but can also be dangerous (the NTSB accident files are full of these situations). Too far forward and the plane could have difficulty on takeoff or landing. Too far back narrows the safety margin between cruise and stall. Performance is also degraded if the center of gravity is too far forward. And note that the CG moves during flight as fuel burns, so you need to predict the CG range throughout the flight.

LaserSailor

Fox Airlines?

Cheap Fares and Balance?

Fuel load is a significant part of Plane mass, so depending on how much fuel is on board the balance is not a simple one size fits all.

Sure you can compensate with trim, but what if trim function is lost? Two things causal to an incident is way too few, to achieve the safety margins needed for air travel.

What if you lose all three redundant hydraulic systems at once? Even then, a pilot wearing Haynes underwear managed to drop the plane down from FL300 and land it.

Pilots worrying about stuff like this is why flying is six sigma safe.

mahasamatman

Not necessarily if you exceed the published limits.

LEONIDES

This has happened to me multiple times, on flying the SPI-ORD route on those cheap Canadair buckets that Skywest operates. On my last hop out of SPI, I had to be move from row 1 to the back of the plane. This was on a Wednesday, and the plane was only half full - which explains why weight balancing was a problem. It was only a 30-minute flight, so I did not care.

kettle1

Is this FT constant think? After takeoff was she allowed to return to her paid seat?

Would she rather be on a plane that could crash because her a*s would not move for 4" of leg room.

I have been in FC and been asked to move back, than returned to my assigned seat after take off. Than I had my "warmed" nuts and g&t.

All was well, as we landed safely.

mike1968

Seems like the 319/20 can carry a heavy cargo load. Was on a flight ORD-SJC in mid 2000s and pilot told us we had heavy cargo and would use the full length of 32L (starting at far end before the 9/27 intersect; same as Hong Kong bound 747). he didn't say what cargo we had, but it was one of the most unnerving take offs I've ever had as we did use most of the runway finally rotating by the hangars at the end of the runway with a low nose up position and plane just seemed to take forever to gain any altitude. Don't recall which Airbus, but thinking it might have been a 319. It was a full flight, so no one was moved around.

UA1KPHL

ok but they only made us move a few rows but was told to not move back to rows 7 or 8 after takeoff either..
i dont understand how 10 passengers really make a difference.. yeah the plane was kinda light in the back.