Weight and Balance matters

[Dick Fisher]

On trips with Ryanair from East Midlands to Carcassonne (France), there have been several occasions when seats at the front and the rear of the aircraft have been "blocked off". During the boarding annos, cabin crew have mentioned that the seating restriction is to do with the balance of the aircraft, and previous threads have seemed to confirm this. Is this also to do with the fact that Carcassonne doesn't have the longest runway in the world?

Now, my wife's boss, travelling from Malpensa (Italy) to Manchester with FlyBe earlier this week has had a similar experience. Once on board the Embraer aircraft, the Captain announced that because there was an issue with the aircraft trim (which he said he had never experienced before), he would need to leave 4 passengers behind.

Leaving aside the matter of the generous compensation offered in vouchers and cash, why would this action be necessary? The Embraer is not a particularly large aircraft, the runways at departure and destination airports are more than sufficient, so what exactly is the problem (in simple to understand terms please?)

[Founder]

First of all with Ryan Air they want the Center of Gravity as far as possible to the rear border. This reduces the need to trim the aircraft and thus reduces the aerodynamic drag caused by the trim-elevator. This in turn saves fuel...

As with the Embraer as with all other aircraft there is a maximum take-off and landing mass that has to be complied with. There is also a minimum amount of fuel the aircraft has got to have for emergencies or extra holding in the air. I can only speculate that the captain of the Embrear was adhearing to these regulations regarding the amount of extra fuel the aircraft has to carry on-board...

As you can see this has nothing to do with the amount of runway there is available...

Kind Regards
Tim

[BOAC]

Founder - your para 1 is the way I have always seen it too, but check post#17 by 'Matty J' in http://www.pprune.org/forums/showthread.php?t=274606 and see what you think?

[Founder]

His reply sounds pretty strange. During my Mass&Balance when studying ATPL we had a RyanAir pilot as teacher. He explained it the way I mentioned above, but it seams very strange that they're loading the bagage in the front hold first...

I'll have a talk with F/O tomorrow if I see him...

Kind Regards

[john_tullamarine]

First of all with Ryan Air they want the Center of Gravity as far as possible to the rear border

.. but surely not at the expense of revenue .. other things being equal it would be silly to leave revenue behind provided the revenue outweighs the cost of increased fuel burn. More likely pax/bags will be left behind because the loading cannot be reworked to accommodate the available load within the weight and CG limits. It would be equally valid, commercially, to do so if the time delay were likely to cause subsequent schedule disruption or related costs .. eg in respect of curfews and slots.

Several considerations -

(a) with the same Type/Model/configuration/empty data .. then one aircraft should be the same as the next for loading .. vary any of the basics and you have different loading scenarios.

(b) no system gets it right all the time. Hence the best systems have a multistage approach to loading so that there are a few spots where checks and balances are expected to pick up on the screw ups

(c) the operating crew member who does the final check on the load is the final opportunity to detect a problem

(d) the best system I have seen for speed and accuracy involved ground personnel running up a trim sheet (doesn't matter whether it is manual or electronic) using company SOP loading and local flair. The crew then ran the final cockpit checks with the FO spinning a circular trimsheet prayerwheel and the captain calling the loads and running the totals. In the freight world this should also involve a crew member running an eye over the physical load (either as the cans are loaded or after, depending on configuration) and making sure that what the sheet says .. is what is on the aircraft.

(e) let your guard down and, sooner or later, you will have raised eyebrows or worse .. especially in the freighter world. Doesn't matter how good a stick and rudder man you are ... run the CG too far aft and the aircraft will give you a BIG surprise (I know of one TP who managed to get such an aircraft around the circuit and back on the ground) .. back a bit further and, with a dynamically unstable loading .. it is a guaranteed crash off the end of the runway ...