atakacs
For the A320 specifically
Reference Airbus Operational Telex 999.0059/19
- In case of unfavourable aft CG position behind the newly outlined limits
- when not in clean configuration
- while the aircraft is decelerating i.e. from a certain max flaps speed down to minimum reasonable speed ("Vls") -10 kts
- then, if in close sequence TOGA thrust is applied and
full back stick is pulled
A computer simulation executed as a part of further FCS development efforts revealed that an excessive pitch attitude might result. It was never encountered in service or during a flight test.
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The pitch can still be controlled with normal sidestick input, just by releasing the full aft grip.
Yet that excessive pitch is not supposed to happen under normal control of the FCS system. There should be a "hard stop" where the elevators are manipulated (behind pilot's back) in such a manner so that the nose would stop raising - even with full back stick being pulled.
A speculation on my part is that the "over-ruling" of the pilots full up input and the pitch-up moment of the underslung thrust is too soft in the "wobbly CoG area" (see Aihkio above). Thus in the future versions the FCS will be allowed to flex more muscle.
It is not a stability nor controllability issue of the airframe aerodynamical configuration. E.g. with abnormal hydraulic the A/C can still be flown properly through the G/A manoeuvre with only one elevator or frozen horizontal stabiliser - in the full original CoG range.
That's the cart and horse.
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If the airline's specific configuration is
very tail heavy when empty, loading upfront might be a challenge. That being said, in the common tkof range 60t+ I really do not remember seeing TO CG above 35 all that often. Allegedly LH needs to take action.
What can you do in case you had to?
- Load bags to front, or even carry ballast there
- Play with the pottable water tank load (tiny little)
- Put your half-load pantry into the front galley
- If fuel is less than 8t (around-ish), transfer the outer wing tanks into inners
- Carry ballast fuel in the centre tank (the issue looks more critical at low weights and this would work nicely)
But none of those are, ehm, "operation personnel proof". The solution no to sell the last few seats is rather charming if it does the trick,
- the seats are easily blocked in the DCS systems
- you can put pressure on the OEM due to lost revenue
- with a good pricing system, you never really sell full 100% seats (though I believe LH to be super-efficient)