Loading is a bit tricky on the 747 Combi....
With light pax load but heavy cargo load, it may be required to hold pax on board until at least 2 maindeck pallets are off the plane. As positioning the maindeck loader is kind of tricky due to the sweepback of the wing, this may take more than a few minutes.
Alitalia had a 17 position B747 combi with pax only in zone a and b...If you were the transit station (as I was in SIN) it could be a real bitch to get in trim.
To expand a bit on the MD11, most people would be surprised that for an aircraft which was so tail-heavy empty, it was really difficult to get a fully loaded MD11 in trim as the CG would be way out the nose! Load planning would start in the warehouse where position 13C and 14C (rearmost) would be loaded /with the heaviest and densest cargo (sounds odd don't it?). Pos-14C had a limit of about 3000kgs and pos-13C was higher at around 4500-5000kgs. You'd then work on 11L/R and 12L/R (unique contours), getting these as heavy as you can.. this was made more difficult with the lesser volume compared to pos 13/14.... You'd then plan/load the lightest cargo on positions 1L/R (unique contours), this may not be always possible as accessible DGR cargo may need to be loaded on these. Pos 2-10 were normal contours so you'd load the heaviest rearmost and plan lighter pallets progresively to the front.
Sequence loading was used to ensure that the aircraft didn't tip. The sequences are as follows..
1. Starting with an empty aircraft, load the forward lower deck.
2. Load maindeck pos 1L and 1R.
3. Load pos 14c/13C but hold these pallet at around pos 7 or 8.
4. load around 5-6 pallet on the left lane. starting with pallets for positions 7L to about 12L. These pallets will temporarily occupy positions 3L to 7L.
5. Load 5-6 pallets on the right lane.
6. You now have at least 14 pallet on the maindeck and 5 in the lower deck so you can now move positions 14C and 13 C into position (they were parked midway remember?
7. Once 14C and 13C are safely locked in place you can move the right side down one at a time, feeding in more pallets as space frees up.
8. Once the right lane is loaded, you do the same for the left lane.. move the pallets in the left lane one at the time while bringing in fresh pallet as space frees up.
9. Load the aft holds.
Done...
This method is probably overkill as throughout the loading process the nose will be very heavy, an experienced loading supervisor will be able to move things along faster. A good main-deck loader operator is an asset, if he needs to keep on correcting the height to allow the loader to be level with the aircraft maindeck.. he will alert the loading supervisor.
Transit load is a bit different as you want to minimise the number of movements as much as possible.. this is where good load-planning in the warehouse pays off.
The MD11 needed several ULD contours.
1-1L
2-1R
3-2LR-10LR
4-11LR-12LR
5- 13C
6- 14C
The MD11 had another foible whereby there was a limit for the weight difference between left and right side ULDS (including lowerdeck LD3s), if you exceeded the limit your MTOW was reduced. I dont have any manuals with me so dont have the actual weights available. I understand that this was necessary to limit the sideways stress on the landing gear.
The 747F was way simpler to load..you only really needed the tail-stand if the nose door was in use at the same time.
Anil