Paralytic

I had exactly the same on an Aer Lingus EDI-DUB a month or so back - no idea what type of aircraft it was, but it was a prop. There was roughly 18-20 rows (2x2) and I was half way back. On landing, the front half of the cabin was told to stay seated while the back half disembarked from the rear, due to balancing requirements.

Calchas

I understand that rear loading is more efficient. I do not understand why.

Perhaps a lurking pilot or aerodynamicist would enlighten me?

cynicalmoose

Perhaps to avoid something like this happening:

Paralytic

It wasn't the rear loading that was notable (this aircraft had no passenger front door), but the fact that the front half of the cabin were told to stay seated until the back half had disembarked. It wsa explicitly stated it was due to the balancing of the aircraft.

Calchas

By rear loading I meant, loading the aircraft weight strongly towards the back of the plane (balancing the weight distribution rearward), not the passengers emplaning/deplaning via the rear doors.

I was assured that a rearward weight balance is more efficient during cruise (perhaps the nose points up more easily? ). On the TCX flights I mentioned earlier, the cargo/baggage was deliberately put as far back as possible. Thus if the front cabin deplaned first, it was implied that the whole plane would tip back (or more prosaically exceed some maximum permitted weight distribution on the rear gear).

However the reason for this efficiency saving over a balanced distribution escapes me.

Sigwx

In a nutshell it is mostly to do with the drag associated with the horizontal stabiliser at the rear. This stabiliser creates a downwards force as opposed to an upwards force created by the wings. The horizontal stabiliser or 'stab' for short required trimming to allow an aircraft to pitch up and settle at the engine out climb speed (V2) in the case of an engine failure during take off.

During the cruise the horizontal stab creates a downwards force to counteract the moment arm between the centre of gravity and the centre of pressure (lift).
The further forward the centre of gravity the more 'up trim' required and consequential drag increase.

More drag=more fuel. Airlines can also use certification specs on certain aircraft types to impose a more limiting forward centre of gravity limit. This enables better take off performance to be obtained (weight lifted).

Ironically an aircraft flys better in an engine out condition with a more forward centre of gravity. But we tend not to see so many of those these days.

Calchas

^^^ Very clear explanation, thank you.

LHR/MEL/Europe FF

Not BA, but A321 related - I flew last month in the USA, peak morning flight that was 'elite' heavy. During taxi they asked all pax behind First class to move to behind row 16. F class exempt. But some 50 pax had to move towards the back of the plane for take-off.

KARFA

BA1345 LBA-LHR for tomorrow evening 2100d. Seems the row blocking has gone back even further than last time I posted here. Must be because I am a GGL now and I get the first 15 rows blocked rather than just the first 9 when I was a GCH

crazy8534

That is hilarious, KARFA!
When you are sure that everyone is on board you should stand up, turn around and shout at the top of your lungs: "And bl**dy stay there!!"

KARFA

Lol ^. I might try it and report back!

Genius1

I have only once experienced the cabin crew checking loads on the flight for trim purposes, and that was on a small Dash aircraft operated by Porter Airlines.

paul4040

Maybe they just think you're really heavy.

KARFA

it's a glandular problem, honest