Non pilot speaking. A possible reason for flyin_phil's flight to have the few pax at the back is because the fuel is basically across the centre of the machine in the wings and a centre tack. So they would want to counterbalance with pax down the back? I sit to be corrected.

Paxboy - sit down! (sorry - but you asked!)

I don't know for this aircraft, but for the B757 I fly, the centre and wing tanks are based pretty much around the C of G, so as the fuel is used, the C of G change is minimal.

Flyin_phil is most likely right - there may be all sorts of cargo in the holds that you aren't aware of, and may weigh much, much more than the pax load.

It also may make it easier for the CC to look after everyone if all 44 pax are in one place as opposed to all over the aircraft - as long as M & B isn't compromised.

Hope this helps.

DW.

You'll find most scheduled flights with assigned seating will have particular seating restrictions when the flights are not full.

I can't comment on the particular 767 query, as I have little experience with them, though 40 people sitting upfront in an empty 767 may have put it out of trim, maybe not. In my experience we'll generally start loading cargo in the rear unless the aircraft is particularly tail heavy, rather than the front so not sure about that possibility, unless it's BA specific.

Who knows, but yes blocking off rows for weight and balance is a valid reason. Might seem hard to believe, but take the first three rows on Ryanair or easyJet, 18 seats, average of 76kg per person = 1368kg. It all starts to add up, especially when there is very little towards the rear to counteract it.

And on the 737 you have 4+ tonnes of engine ahead of the C of G.

Remember alot of the weight on the aircraft is fuel.. so on a B767, my guess would be, yes, that there was alot of cargo in the forward hold, and/or that the amount of fuel onbaord required more weight in the back to move the center of gravity and get the a/c balanced.

I stand corrected, but I as far I can remember, there is not left/right balance. The fuel loading is the main factor here with the amount of fuel in each wing - but pax are right in the middle of the vessel, having so little movement to play with between left and right weight. I'm not a pilot, but if I am right, the x-feed would be used to correct an imbalance between left and right tanks...

As dwshimoda has said, the wing fuel has a short moment arm around the CG limits on most aircraft, precisely to minimise the amount of trimming needed as fuel burns.

All other things being equal, an aft CoG is preferrable for fuel consumption and stability/handling reasons, so it could be that the Istanbul 767 mentioned earlier had few passenegers and little cargo.

This happened to me once whilst on a FR flight back in '06.

Whilst boarding, we noticed that a good few rows were blocked off with tray tables down.

So, yes, the 738 does suffer from it as it's obviously a narrow-body and quite long. :ok:

With Ryanair isn't it also something to do with where passengers' luggage is loaded? (I seem to recall reading this somewhere - on PPRuNe?).
I'm surprised that Ryanair sometimes also blocks off rows when the aircraft is really quite full. Once or twice I've seen Ryanair flight deck crew permit passengers who've complained to use blocked off seats.

Since when do F/D crew do the boarding? :}

This is what we call Rule 1. When the load is 177 pax or less (capacity as i'm sure you know is 189, so it would be a quite full flight), we block off rows 3 and 4 for take off and landing. During cruise pax are free to sit there should they chose to. Hope this helps.

Rgds,
ATS

Thanks, ATS.

I sit at the back - except when travelling to Madrid - usually in row 32 (or 33 now that my hand luggage can be stored under the seat), and have noticed rear rows blocked off when aircraft seem to be as full as you describe.

As far as flight deck crew allowing passengers to occupy blocked off rows is concerned, I've seen this twice. On one occasion, a flight attendant went forward to the flight deck and returned with permission; on the second, a member of the flight deck crew actually came aft.

Keep in mind that some of the destinations RYR flies to are performance limited, meaning that you will never seen a full plane going to those places, regardless of demand.