Monday, 24 November 2008

Heavy Play

Following on from my last post, Aviatrix has published two interesting posts about weight and balance on Cockpit Conversation . Have a look at those if you want to know a bit more.

In my company, we do get wide body aircraft on a regular basis during the peak season. During the off-peak season we're in now, they are few and far between but we still get the odd ad-hoc charter passing through our hands. I had the luck of the draw recently for an A330 passing through us, destined for shores more exotic than my own.

The flight was a split-load with another airport, and positioned into us with passengers and cargo already on board going to the same destination. They remain on board the aircraft as my passengers join them and we load the holds with more bags and top up the fuel.

The basics of loading a wide body are much the same as the smaller aircraft I discussed in my last post, in trying to balance the weight to get an ideal trim. But sometimes with wide body aircraft it can get a bit more complicated. On this particular A330, there are belly holds at the front and rear of the aircraft. Some versions of it also make use of the area between the wings.

The flight is bin loaded, meaning that all the suitcases are in aluminium containers called Unit Load Devices (ULDs). They come in various shapes and sizes to fit aircraft holds. For example, on A330s we can use AKE and ALF type bins, but on 767s we have to use DPE and DQF bits. The dimensions and shapes are different to allow them to fit snugly in the hold of each aircraft without wasting space.

We're using AKEs and ALFs to load this flight. ALFs are large containers that span across the belly hold from left to right, where as AKEs are half the size and you can fit two side by side in the aircraft. We load and count the bags into these bins, and then work out the gross weight of each.

I have a plan view of the aircraft's holds, depicting the different locations we can load the ULDs or cargo pallets. The diagram is marked with squares labelled 11L, 11R, 12L 12R, 13R etC. The first number is the hold number, and the second number is the row number for the ULD, followed by L or R for which side of the aircraft. Eg 13R is Hold 1, row 3, on the right side of the aircraft. We can fit 1 AKE in this position, or 1 ALF positioned across 13L and 13R. Cargo pallets are bigger yet again than ALFs and have their own divisions that span across the hold and over 2 rows. Their divisions are labelled 11P, 12P etc.

The aircraft arrives at my airport carrying carrying bins and cargo pallets from it's first departure airport. The handling company there has placed all their cargo and ULDs in the rear holds, and taken up all the available positions leaving me only the front hold to place my outbound ULDs. The ramp guys have managed to fit all our bags into 3 AKEs and 1 ALF, and I also need to load some empty AKEs that are to travel to the destination at the request of the airline's ULD Stock Control people.

A quick count reveals there are 14 AKE positions in the front holds, or can be used as 3 pallet positions and 2 AKE positions. The rear hold has room for 2 pallets or 6 AKEs. I plan to put the ALF at the rear of the front hold, nearest the wings, with the loaded AKEs in front of this, followed by the empty AKEs. Today it's easy enough, but on the return flight with the split load it could get more difficult. Generally if an aircraft has two destinations, the handling company at the departure airport will load it so the first destination cargo and bags can be offloaded without moving the remaining the cargo for destination 2. Sometimes, it's not always possible though as it results in the aircraft being too tail heavy, so we would need to remove ULDs and pallets to get access to our ULDs, and then reload the bins and pallets for the next destination.

On the other hand, if we are able to remove our ULDs without moving anything else, the result might be the aircraft is out of trim now and so we need to move the remaining weight anyway. It's good practice to try and plan it so it works out easily for the ramp guys the other end. For you can be sure if we make it difficult for them, they can end up doing the same for us when the aircraft returns! With so much to consider, it's easy to get caught up in the loading of the aircraft alone and forget about the other things that need done.

Upstairs, the first of 186 passengers are already boarding and taking their seats for a long 9 1/2 hour flight ahead of them. I'm used to working with smaller aircraft so much that it still surprises me a little when I step on board and notice the size of them inside and galleys big enough to put restaurant kitchens to shame.

Fuelling is taking place, the crew have requested 68,000kg of jet fuel. That's a lot, and still makes me go 'Whoaa' when I think about it. A fuel truck is parked under the wing pumping fuel in, and another truck is waiting behind it. I can see the drivers are bored sitting watching the gauge tick over, gallon after gallon. It takes a long time to uplift 68,000kg of fuel.

Once the positions of each bin is decided, loading is speedy and finished well ahead of the scheduled time of departure. It's a good day, all my passengers turn up and board on time too so all I have to do is wait for fuelling to finish before we can go.

Fuelling finally finishes and paperwork complete, I say goodbye to the crew and let them close up. I do my walk around feeling like a little kid in a big playground. I'm looking for anything unusual like I discussed in my Walk Around post, but I'm also in awe of the size of the aircraft. The main deck sits well higher than any other aircraft I deal with, the wing span is massive and I can see the wings drooping under the weight of the fuel. We begin the push back and the tug struggles a little at first. Pushing 204,000kg of aircraft takes a bit of grunt, especially on the slight incline we have. The engines start up and I get a nice whiff of jet fuel as I hear that resonant hum.

Push complete, we disconnect the equipment and I wish the crew a good journey. I have to walk a few miles away before I can even make eye contact with them and show them the pin because they're sitting so high they're almost in orbit.

A few minutes later, I hear the engines spool up and it starts to accelerate down the runway. The engines make a fantastic snarling sound of a roar that makes the hairs on your neck stand up. It speeds past me, I see the wings load up and a few seconds later the nose lift gently off the runway. The main gear lifts off and assumes its usual angled position before being raised, and off into the cloud it climbs gracefully...


Blake said...

Great post. One question.

I noticed that you're dealing with metric measurements. Does that mean your in Canada? or has the airline industry standardized on Kgs for fuel weight?

Or.... is it just up to the crew to give you measurements in whatever units they specify then you have to make calculations accordingly?

Also. Do the fuelers take into account the temperature of the fuel? Or do they use the fuel weight at standard temp? (15C)

Dispatcher said...

Hi Blake,

I use metric as I'm in Europe. Almost everyone I deal with uses metric, except MD80 variants airlines which in my experience always use imperial. I don't deal with any American airlines at all in work.

I don't know about the fueler's method, I'll ask them next time I get a chance. I don't take much to do with fuelling other than pass the figures if they need them.

Wayne Conrad said...

Another great entry.

Here's an unrelated question that I've wanted to ask for some time. I remember reading somewhere that dispatchers take the same written test that air transport pilots take. That makes me curious to know how you become a dispatcher and what hurdles you have to jump to get there. If you think that'd be a good blog entry in the future, well, I'm interested in how you got to where you are. Thanks!

Blake said...

Oh awesome thanks! Sorry for making the assumption that you were in North America ;)

Yeah.. we're all metric up here in Canada. However, I'm unsure how dispatchers, fuelers deal with American planes.

Do a search for "Gimli Glider" for an example of a lbs<->kgs conversion error and accident. This was back in the 70s when Canada first went metric.

Anonymous said...

dispatcher, you are great. thanks for post.

dpierce said...

Very interesting! It brings up a question about bulk loaded baggage. If your bulk loaded baggage is going to split destinations, I assume it also is loaded in such a way so that the first destination's baggage is nearest the hatch(es)?

If so, is there a physical demarkation between the two sets of baggage in a hold? (Netting, barbed wire, etc.) Or do they simply keep removing bags until they get to the chunk where the tags no longer match?

Dispatcher said...

Wayne and dpierce,

Good questions, I'll cover them both in a bit of detail this week.

Thanks for reading