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adools
Topic Author
Posts: 49
Joined: Tue Oct 03, 2006 5:16 am

Weights & Balances EMB 145

Thu Oct 30, 2008 1:10 am

Hi All,

I recently flew from Denver to Little Rock, AR on United EMB145 (operated by one of their express carriers). I sat in seat 1A originally. After boarding, the cabin crew asked me to move to 11C. That was the only free seat left and she gave the reason "weights and balances." On a full flight (during the flight only 1A was free) why does shifting only one person make such a difference? Seems that my weight (200 lbs) is insignificant to the whole fully loaded plane?
 
ThePinnacleKid
Posts: 540
Joined: Wed Feb 23, 2005 9:47 am

RE: Weights & Balances EMB 145

Thu Oct 30, 2008 5:00 am

Depends on the the loads of bags we have on board as well as the fuel we have...

On the 145 I tend to see 2 scenarios we routinely need to move people...
1) lots of people and few bags
2) all together a very light load (people and bags)

Sounds like in your case it was more of scenario 1.

Quoting Adools (Thread starter):
That was the only free seat left and she gave the reason "weights and balances." On a full flight (during the flight only 1A was free) why does shifting only one person make such a difference? Seems that my weight (200 lbs) is insignificant to the whole fully loaded plane?

I understand where you're coming from.. it does seem crazy that your weight (184 lbs at my carrier) would make that big of a difference, but you have to realize that the plane is balanced like a huge teeter totter more or less (the further your seat is away from the fulcrum of the imaginary teeter-totter the more of an impact your weight shift will have) ... You moving from seat 1A to 11C is a shift of 3 or 4 zones out of 5 zones available (can't remember the exact number without seeing the f/a count tablet (again at my carrier)).. that is the same as moving three people from say row 10 to row 18... the whole cabin is weighted out compartmentalized... at my carrier the 145 is divided into 5 "zones".... each time a single passenger is moved a single zone that is a move of 1 unit.. sometimes when running weight and balance I need to move people say 3 units.. so I can either move 3 people from a middle area to the back.. or I can inconvenience 1 person and move them to the back from the front and solve all the problems...

In your case.. what it can be (since there was only 1 seat available.. so a boat of 49 people).. by moving you in essence 3 zones I might have either reduced the amount of ballast needed to be carried to be in balance or completely eliminated the need for ballast all together.
"Sonny, did we land? or were we shot down?"
 
744rules
Posts: 391
Joined: Sat Mar 30, 2002 3:34 am

RE: Weights & Balances EMB 145

Thu Oct 30, 2008 9:08 pm

remember the w&b for the ERJ operated on behalf of BA. Full (male) pax flight gave it out of balance in the front. Adding ballast gave an overweight. Offloading pax was the only solution.
 
pilotpip
Posts: 2844
Joined: Fri Sep 19, 2003 3:26 pm

RE: Weights & Balances EMB 145

Thu Oct 30, 2008 11:28 pm

That flight was likely operated by TSA. Many of their 145s on the UAX stuff don't have thrust reversers. This makes an already nose heavy aircraft even worse. It was pretty much an occurance on every flight when I worked there. If there are open seats, move everybody back.

When the FO did the calculations, he/she probably found that the aircraft was in the forward caution zone. Not outside of CG, but it could be if something changes (moving the galley cart, etc). As a result, all empty seats must be in the first seating zone on the CG computation (rows 1-5 if I remember correctly).

Hope this provides some insight. On the 170 it's the exact opposite. However people usually don't complain about being moved to first for free  Smile
DMI
 
JER757
Posts: 165
Joined: Thu Jun 01, 2006 7:48 am

RE: Weights & Balances EMB 145

Fri Oct 31, 2008 1:17 am

Why is the ER4 so nose heavy? Is it specifically designed like that to counteract the weight of the engines at the back?

Come to think of it, i've never a tail heavy 145... What do you have to put in the back hold to make it so? (I don't have a manual loadsheet with me!)
Gale force fog... don't you love it?
 
pilotpip
Posts: 2844
Joined: Fri Sep 19, 2003 3:26 pm

RE: Weights & Balances EMB 145

Fri Oct 31, 2008 1:36 am

Don't know. I think it is just an additional effect of being an adeptation of an airframe that was already flying (120). Further agravated by many of TSA's 145s not having reversers, so even more weight is removed from about the most aft possible on that airframe.

The 170's CG is more towards the tail and every now and then you bump into an aft issue but it is never too far forward. Of course, an AFT CG is "better" for a lot of reasons.

[Edited 2008-10-30 18:38:13]
DMI
 
Cubsrule
Posts: 15179
Joined: Sat May 15, 2004 12:13 pm

RE: Weights & Balances EMB 145

Fri Oct 31, 2008 3:23 am



Quoting Pilotpip (Reply 5):
Further agravated by many of TSA's 145s not having reversers, so even more weight is removed from about the most aft possible on that airframe.

Though it might not seem like it, this is really what makes the difference. I can't remember the last MQ or RP flight I was on where we had to move people around. I can't remember the last AX flight I was on where we didn't.
I can't decide whether I miss the tulip or the bowling shoe more
 
AirWillie6475
Posts: 2372
Joined: Thu Jan 27, 2005 1:45 pm

RE: Weights & Balances EMB 145

Sat Nov 01, 2008 5:59 am

Yes, one person can make a difference in these small airplanes. Moving from 1A in the ERJ is actually better because besides the FA jumpseat, 1A is probably the loudest seat in the airplane. Row 1 through 6 are loud on the ERJ because the body is the same as the prop version, not really designed for high altitude flight but still pressurized well, the Brazilians signed it off.
 
pilotpip
Posts: 2844
Joined: Fri Sep 19, 2003 3:26 pm

RE: Weights & Balances EMB 145

Sun Nov 02, 2008 2:42 am

Believe it or not, you can tell when somebody is walking back and forth, especially if you're hand flying. FA or pax makes their way to the back and you're going to be retrimming.
DMI

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