Slot City

I'm on the 4th of 6 early starts. Each day I'm awoken from a deeper sleep by the alarm clock at o'dark hundred and each day the disappointment gets greater and greater as I realise I am actually working, rather than forgetting to turn the alarm clock off or it being a bad dream.

It's a case of dejá vu each morning, the quiet roads on the way to work, the same aircraft sitting awaiting departure each morning, and equally unfortunate bleary eyed crews turning up and exchanging sympathies about how many earlies we're doing. Greeting most pilots in the morning, after the usual mutual moaning of fatigue the next question is always 'Is there any slot?'

Early morning is a busy time for both airports and the airspace around them. With a wave of departures all wanting to leave at the same time and follow the same pieces of airspace to the same destination, or destinations close by, their flow has to be regulated. That's where the black art of slots come into play in Europe.

I don't work in flight planning ops or air traffic, so the following simplified explanation will probably leave some banging their head and comparing me to an uninformed journalist trying to report on some minor aviation incident, but alas, I'll have a go.

Each flightplan filed in Europe goes through a computer known as CFMU, or Central Flow Management Unit. I imagine it as a massive super computer stored in a darkened room with it's own micro-climate, with many operatives nurturing it and keeping it happy. In return, it will crunch many numbers and try and attain the most efficient use of airspace around Europe, keeping things moving and preventing bottlenecks at busy spots. To attain this regulated flow, it devises a time for each aircraft to depart/arrive/pass overhead a point, and this results in a Calculated Take Off Time, or CTOT. Since modern flight planning is so precise, sectors of many hours can usually be accurate to a minute or so easily, it churns out a CTOT for a flight so that it should progress smoothly.

This CTOT, or slot as it's commonly referred to, is the time the aircraft should be taking off at. This puts added pressure on everyone, if the slot is missed it could be a long time before the flight gets another one. Although the CTOT is an actual time, there is a discretion of -5 to +10 minutes that provides a window that the aircraft can depart in. However, it's to be used only by the local Air traffic controllers, to allow them to work the aircraft into the flow of traffic on the ground, since it won't always be possible to have it at the runway at that exact time. For us the ground crew, we're working to get the aircraft off stand 10, 15 or 20 minutes before the CTOT, depending on the ramp traffic and taxi time.

So on any early morning, it's not unsual to have most of the departures having slots. This messes up the usual order of departures we would be expecting, as a flight due to depart at 0630 may have a slot of 0720, but a flight due to depart at 0635 may have a slot of 0642. It's also not unsual to have a slot that results in the aircraft having to depart the gate early in order to make it. Slots often tend to change as well, as the traffic flow changes. In the space of the hour leading up to departure, it can be common to have the slot to change three or four times, jumping forward or even backwards.


Finally getting around to taking a picture now and again, without giving too much away about where I work. Below is one I took recently, the panel located on the back of the nose gear strut of a 767. You can see some of the buttons I talked about in a post last year when discussing the headset conversation. Don't be tempted to push the large red or black button...unless you really need to! You'll just create endless amounts of paperwork for yourself, and a no tea and biscuits meeting with the manager.



The headset lead plugs into the jack on the bottom left, titled Flight Interphone. The wheel well light switch controls a light inside the wheel well so it can be easily inspected, and the switches relate to the APU, so that it can be shut down and the fire bottle discharged should anything happen.

2 earlies to go...then some proper sleep!

SITA Message Examples explained...

So despite the cryptic code, a few of you were able to decipher the bulk of the message which is more than I could do when I first started. Here's a quick explanation of the message examples I posted.

Starting with the departure message:

MVT
RAT0123/09.ECENZ.IST
AD1245/1253 EA 1559DUS
PX323

It's a Movement (MVT) message for flight number RAT0123 on the 9th of the month, aircraft registration EC-ENC, departing IST or Istanbul. The flight departed, as in off-blocks time or push back from the gate) at 1245z, and was airborne 8 minutes later at 1253z. It's estimated arrival time in DUS, Dusseldorf is 1559z, and it has 323 passengers on board.

The arrival message is pretty similar:

MVT
RAT0123/12.ECENZ.IST
AA1340/1354
SI NIL

It's a movement for RAT0123 again, for the 12th of the month, aircraft EC-ENZ arriving at Istanbul. It touched down on the runway at 1340z, and was on blocks at 1354z. The SI section is for supplementary information. We might use it to explain there were no stands available upon arrival if there is a large interval between touch down time and on blocks time.


The Load message:
LDM
RAT0123/09.ECENZ.Y323.3/8
-DUS.161/119/43/19.T.9335.2/2105.4/5330 5/1900 PAX/323 B/8775 C/1450

It's a Load/Distribution message for RAT0123 on 9th month, aircraft again EC-ENZ, with a seating configuration of 323Y, Y denoting economy class. 3/8 is the crew configuration, 3 flight deck member and 8 cabin crew.

Destined for Dusseldorf, there are 161 males, 119 females, 43 children and 19 infants (yikes!) Some airlines rather than using males, females, children and infants will instead using adults, children and infants, in which case it would read -DUS.280/43/19.

In the holds, there is a total of 9335kg of cargo and bags.
In hold 2, there is 2105kg,
In hold 4, there is 5330kg
In hold 5, there is 1900kg
There are 323 passengers on board, and of the total load in the holds, 8775kg of it is baggage, denoted by the B/8775, and the remaining 1450kg is Cargo, denoted by the C.
If it were a multi stop flight, say continuing on to Heathrow, it would have another line beginning -LHR with similar information on the load destined for Heathrow.


Finally, the CPM.
CPM
RAT0123/02.ECENZ.31904H01
-11L/PKC/IST/630/C
-12L/AKH/IST/600/C
-41L/AKH/IST/620/C
-42L/AKH/IST/583/BC/BY0
-43L/DZH/IST/96/E/BY
-5/IST/50/BY
SI - TWO BABY-STROLLERS IN CPT 5

The anonymous reply to the first post mentioned when reading CPMs, they picture it as an aircraft, which is a good idea to help understand it. By now you'll probably now it's a CPM message for RAT0123 on 2nd of the month, aircraft ECENZ. The 31904H01
part I'm not actually sure about, usually it mentions an aircraft type but I'm not familiar with these numbers. Any of my readers able to educate me?

Referring back to one of my old posts about widebody aircraft and their loading, that will explain the hold positions mentioned in the CPM of 11L and container types such as AKE and ALF.

The CPM simply describes what is located in each position in the hold, a bit like a more detailed LDM. So for the example, in position 11L, there is a ULD container, type PKC, destined for IST weighing 630kgs and contained Cargo. Similarly, in 12L and 41L there two AKH type containers for IST containing 600 and 620kgs of cargo respectively. In 42L, there is another AKH container with 583kg of club class or business class baggage, denoted by the BC, and no economy baggage denoted by the BY0.

In most aircraft I have dealt with, if they have a hold 5 it tends to be a smaller bulk hold in the tail of the aircraft where crew bags will go or last minute gate items. In this case, there is 50kg of economy baggage, and the SI section explains that it is two baby strollers/prams/buggies, call it what you will, or I prefer dpierce's explanation of "a duo of infant conveyances may be discovered in the fifth of the aircraft's various and sundry compartments."

I'm not sure whether part of the CPM got lost in the formatting while posting, or whether the example just didn't have it, but it should have twice as many lines or at least be twice as 'wide,' listing the contents of the right hand positions in the aircraft, so 11R, 12R etc.

The more you work with these messages the quicker you become at reading them. On a busy day in work, messages like these will be pouring out of a telex printer constantly together with other types of messages. As such, unless you keep up with it you'll find yourself with 30 ft of paper to go through looking for the information you need and checking you haven't missed anything!

SITA Message Examples

After my last post, Wayne asked just how cryptic the SITA operational messages we use are, so here are a few examples of each type. I ended up finding these examples in a few online manuals after some googling as opposed using some from my own place of work, that would only give away my anonymity!

Starting with a departure message:

MVT
RAT0123/09.ECENZ.IST
AD1245/1253 EA 1559DUS
PX323

An arrival message:

MVT
RAT0123/12.ECENZ.IST
AA1340/1354
SI NIL

A Load Distribution Message:

LDM
RAT0123/09.ECENZ.Y323.3/8
-DUS.161/119/43/19.T.9335.2/2105.4/5330 5/1900 PAX/323 B/8775 C/1450


And finally, a Container/Pallet message:

CPM
RAT0123/02.ECENZ.31904H01
-11L/PKC/IST/630/C
-12L/AKH/IST/600/C
-41L/AKH/IST/620/C
-42L/AKH/IST/583/BC/BY0
-43L/DZH/IST/96/E/BY
-5/IST/50/BYSIT
SI - TWO BABY-STROLLERS IN CPT 5

Have a go at trying to decipher them, I'll post a brief explanation in a day or two. As a hint, RAT0123 is the 'fictional' flight number and EC-ENZ the registration of the aircraft, I haven't looked to see if it exists.

Ops secret text messaging

Here's a brief insight into the 'secret world' of airline operations and text messaging.

Working for a company that represents and handles airlines at our station, we are obliged to send short text messages to the airlines operations department and other companies that may need to be notified updating them on the progress, or slow-gress of the flight.

Consider a flight for example that departs from my station. Once airborne, we must send a message to the airline HQ as well as the handling company at the destination airport(s) notifying them of the aircraft's departure times, estimated arrival time at destination, and any other significant information such as passengers that require special assistance. The airline HQ receives these messages and it acts as a voiceless method of being able to track their aircraft in real time. Similarly, the workers at the destination airport now know an arrival time for the aircraft and can plan accordingly, so they are ready for its arrival. These types of messages are known as MoVemenT messages, or MVT messages. We send one for every flight we handle, using a specific (primative, but functional) network that we're all connected to.

When the aircraft arrives downroute, the station will send a message back to us and also to the airline's ops department, detailing its touchdown time and on-blocks time. This lets both parties know that the aircraft has arrived safely. These messages are known as Arrival messages.

There are endless other types of messages we use; some are just variations on the message and others are more specific to the loading of the flight. Load Distribution Messages, or LDM are sent in a similar manner. These messages explain how the aircraft has been loaded, such as how much cargo and baggage is onboard, and how its distributed within the holds. These are particularly necessary for multi-stop flights, so we know in advance where the cargo and bags that need offloaded at our station, are located in the holds.

LDMs must be sent before the aircraft is due to arrive down route. Obviously it wouldn't be much use sending a LDM after the aircraft arrives, as we'd have already opened it up and started looking for our cargo and bags. In most instances, LDMs are sent automatically even before aircraft departure, once the flight has been finalised or closed.

Another variation of a LDM is a CPM, or Container/Pallet distributon Message. These are more common with larger, widebody or cargo aircraft. It lists the positions of each ULD or pallet in the holds, together with what's loaded into it, such as cargo, baggage, crew bags or simply empty.

All these messages are sent via a network called SITA, many will be aware of it or even use it and others will have at least heard of it. If you don't fit into either group, fear not, as you aren't missing out on much! Messages sent via SITA are charged for, and usually by the number of characters. As such, all the messages have a strict format of abbreviations and codes that look like random numbers and letters and mean very little to the untrained eye. They take time to get used to, but after that reading them becomes second nature. I can read MVTs, LDMs or CPMS much quicker than I can read some silly text message from a friend using 'txt sp8k.

So there you have it, a quick insight into the voice-less exchange of information between many parties in the airline industry.

Too late for check-in?

Fear not, Dispatcher is alive and well. I took some time off work to pursue other projects, and also to recharge my batteries before the summer season kicks in, I can almost smell it now. The stress, the sweat, the jet fuel, the passengers trying to smoke on the ramp, the arguments... As I expected, nothing has changed in the time I have been away. The crew still look the same, there were no A380 diversions and 787s still haven't appeared. None the less, I have missed it, and I'm grateful for being able to say such a thing. I like to get a vacation as much as the next guy but work is fun and it's good to get back. Now to the more serious issue of blogging!

Following on from a previous post about information sometimes lacking when it comes to delays, and how passengers can feel out of the information loop, I thought I might also cover another scenario in order to inform what is actually going on.

It's common knowledge that check-in closes at a particular time depending on the flight and airline. Some flights may close at STD - 40mins, -30mins, -20mins etc and with good reason. By closing check-in at a suitable time, it should provide enough time for the passengers to pass through the airport to the appropriate gate, maybe even taking in the shops on the way. But behind the scenes it also allows their bags to be screened by security, transported and loaded onto the aircraft in time, and for the paperwork such as passenger manifests and weight and balance sheets to be completed in ample time before departure.

Sometimes this check-in closure time can be a bit more flexible, and we can extend it in some circumstances. If flights are running late, we can often allow passengers to check-in at a time after check-in should have closed, should they have been held up. Because the flight is late, we still deem there to be sufficient time for you to make it to the aircraft without causing any further delay. Unfortunately, due to Murphy's Law the chances are that when you're running late and need to make that flight for an important meeting or family reunion, that we're unable to accommodate you. I'm afraid it's not us being awkward or spiteful, but luck isn't on your side today and we don't feel we could get you on the flight without delaying it.

If a passenger turns up late, pleading to get on the flight we'll do our best to help. The staff will phone or radio through to myself or someone else aircraft side to check on the progress, and whether it's too late to accept the passenger for the flight or not. Rest assured, we do have a heart and a conscience so won't automatically say no each time, however, we do have get the aircraft away on time.

If you have baggage to check it, there's a high chance we'll refuse. It only takes a few seconds to place a bag in the hold, but first it has to pass through the network of conveyor belts behind check-in, be screened by security and find it's way into the baggage make-up area. From there, it has to be transported by the ramp guys to the aircraft and loaded. If the holds are already closed, that would mean re-opening them, placing loading equipment back at the aircraft to get it on board, all costing valuable time.

We'd also have to wait for you to be make your way from the check-in area, through security to the gate areas. Assuming the usual queues at security, and the size of airports, it's almost certainly going to take you more than a few minutes. Remember, we usually assume it'll take you around 20 minutes to 'drift' through to the gate area.

The paperwork regarding the aircraft weight and balance has probably already been completed. If another person is travelling, it will have to be amended. It can be easily changed, but has to be accurate. Most weight and balance sheets I use have a small section entitled 'LMC' for Last Minute Changes. It's used for late off or on-loading of cargo and passengers. For larger aircraft, an extra 76kg for a passenger won't make much of a difference, but for smaller aircraft that are more trim sensitive, it can present a headache. It also starts to look messy as you amend it to onload an extra passenger and bag which then fail to turn up at the aircraft in time and have to be taken off again.

Hopefully that provides a little insight to why sometimes we can and sometimes we cannot accept you after the usual cut-off point.

The Dispatcher has returned...almost

Sorry, sorry... I have taken sometime off work in order to pursue other life projects and recharge my batteries before summer kicks in.

I'm in the middle of writing a post that I should hopefully get blogged this week.

Next Information at...

We've all been there I'm sure, sat at the gate with one/two/three hundred other passengers, as the flight information screen shows your flight as Delayed or Next Information at... The staff at the desk are being berated by your fellow angry passengers demanding to know what the problem is and when they are eventually going to depart. The staff unfortunately don't have any answers which only further fuels the passengers' frustration. Are they just being lazy and unprofessional, do they have really bad news they're too scared to tell you, or do they actually know as much as you do?

I've been on both sides of the fence, experiencing the frustration as a passenger without information about delays, and also as the staff member being at the forefront, being bombarded by a mass of angry passengers. Not a pleasant experience, and so I'd like to explain it from our side of the fence so hopefully you better understand next time it happens.

Depending on which airport you're at and which airline you're trying to fly with, the staff may be employees of another company contracted to represent the airline at that airport. I don't think many passengers actually realise this, that for the most part unless your flying from an airline's hub or one of its larger out stations, chances are all the staff you encounter are employed by a separate company (hence the different uniforms.) They are there to look after you from check-in to departure, and unfortunately all the delays in between.

I work for such a company, contracted by airlines to represent them. I'm not a direct employee of an airline, I wear a uniform that is non-representative of any airline, just my own company. Some of my colleagues do have airline branded uniforms, as they'll tend to work specifically representing that airline in my company. But none the less, they work for a separate company. As such, we aren't always fully aware of what is happening at the airline with regards to delays and cancellations, until the airline decides and then tells us.

We are generally at the mercy of each airlines' operations department in receiving information. These departments lie concealed in darkened rooms, deep in armoured bunkers, filled with computers, marker boards and phones. They are never seen by the public, or even by me, and are staffed by a magical workforce of busy bodies keeping an airline running. Or so I like to think so, given the impression I get when on the phone with them. They're job is on a different stress scale than mine, I can only deal with one aircraft at a time, they're looking after a whole fleet.

So when a flight has a technical problem on the ground, even though I may be standing aircraft side fully aware of what the problem is, talking with the engineers and the captain, I can't always pass that information on to my colleagues to tell the passengers. I am all for giving the passengers all the information I know, but I can't or I'll be slapped on the wrists by the airline's ops department. In these times of small profit margins, and stringent compensation rules, airlines are reluctant to pay out compensation in the form of food vouchers, hotel rooms or refunds. As such, information that is passed onto the passengers is considered carefully, and isn't always available immediately, especially to us as a third party.

Technical problems take time to diagnose and then fix, and it's unwise to estimate the time involved as it'll likely be wrong by a factor of three. Operational problems such as crewing or aircraft rotation issues, constraints with enroute ATC or destination, poor weather, local airport restrictions etc happen regularly but every case is unique and as such a different solution is required. The first solution isn't always the best, so the most efficient (and safest, if that comes into the question) has to be found, but it takes time. So your sitting in the lounge, you can even see your aircraft sitting outside the window, but all you know is it's been delayed. Rest assured that the folk behind the scenes are working on a solution, but until they come up with one, there's no point in giving you infomation that will most definitely be inaccurate.

Believe me when I say, if each time there was a serious delay I could hotel the passengers for the day, I would. 200 tired, angry and frustrated people hanging around in your airport lounge tends to prevent your day running smoothly. But we can only start to organise hotels and accommodate passengers when we are authorised to do so by the airline. Getting them to do this is generally akin to getting blood from a stone. Kent Wein did an interesting post a few weeks ago about a 26 hour delay on one his flights, and makes interesting reading telling the story from the crew's point of view.

For any airline ops people reading, I am not attacking your hard work, and I realise that many of the decisions regarding what eventually happens are made by folk above you, rather than those who keep the whole operation ticking. But hopefully you can sympathise with the situation faced my end, with my colleagues on the front line left dealing with the passengers.

Anyway, I hope that gives you some insight to where the problems lie and why there is sometimes a lack of information. As Captain Dave would say, life on the line continues...

Well in my case, life on the ramp continues...