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Attila Frequently Asked Questions


I tried to comply with the Attila message, but was vectored by ATC?

First and foremost, Attila is a statistical benefit program. Although Attila can, and often does improve individual flights, Attila's main goal is to improve the system solution. As an example of a system benefit, when Attila is operational, the Terminal Area Dwell Time (time from the arrival cornerpost to landing) for all aircraft is reduced by approximately one minute. This means that even if you are not able to make your individual RTA, your flight does benefits from the fact that other pilots were able to make their RTA. Of course, the more often you can make the RTA, the better the system will work. As one pilot stated, "When I receive the Attila message, I am able to comply 70% to 80% of the time, and the more messages I receive, the better I get at meeting the Attila goal". In the current implementation, successfully meeting the Attila RTA 70% of the time is considered successful.
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The Attila time change request is too large?

While the Attila and FMS cornerpost time predictions are usually very accurate, there are times that the FMS cornerpost time is different than Attila cornerpost time. In the thousands of Attila messages sent since Attila went operational, ATH has received only a very small number of error messages from pilots. ATH personnel have analyzed each report in depth. The largest portion of the problems found thus far stem from the FMS. Therefore, if the speed change required by the Attila message seems excessive, the first step should be to crosscheck the FMS calculation. After assuring the winds are entered correctly, simply go to the PROG page and replace the Destination with the target cornerpost fix. The FMS will then show distance (on the FMS routing) and time to the target cornerpost. Then divide the distance to the cornerpost by the groundspeed in nautical miles per minute. For example, if the FMS shows 624 NM to the target cornerpost, and the aircraft is traveling 8 NM/minute, it will take 78 minutes to reach the cornerpost. Absence any large wind changes (usually visible on the Flight Plan), the aircraft will reach the cornerpost 78 minutes later.
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Isn't sequencing FAA's job?

While FAA is indeed part of the solution, it is incumbent upon the airlines to manage their aircraft. From a business perspective, too often aircraft arrive early and wait for a gate, or an aircraft lands early only to delay a late aircraft from the same airline. While FAA is responsible for the safe separation of aircraft, FAA should never be concerned with the business decisions within each airline. As Attila is proving daily, tactical management of the airlines capital production asset can, and must be done by the person that owns the aircraft. Only the airline or aircraft operator knows the economic priorities for their assets at any given moment.
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Isn't there too much confusion and variability in the terminal area to manage the arrival flow?

While we agree that there is a lot of confusion and variability within the terminal area, this is an outcome of not managing the arrival flow, not a constraint to managing the arrival flow.
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Won't Attila interfere with Air Traffic Control or Traffic Management Advisory?

No. Think of the ATC arrival problem like a deck of cards. Currently ATC takes the aircraft as they arrive, and then sorts them out based on the first come, first serve principal. While meeting the safety goal, many times this sequence is very costly to the airline, especially at the network airports. Conversely, Attila takes the random deck of cards and presorts them one to two hours prior to landing based on the airline's business needs. Not only is an "ordered deck" of cards more profitable for the airline, managing a presorted deck makes the ATC task more stable and predictable. In the end, whether the arrival flow is presorted (Attila) or left to random chance (today's operation), the ATC system will do what it does today - tactical changes to insure safe operations of the airspace.
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Won't Air Traffic Control or Traffic Management Advisory interfere with Attila?

No. First, Attila improves the ATC/TMA flow. Further, Attila expects that a certain percentage of flights will be vectored or otherwise modified by air traffic control. Attila will simply mark this particular flight as "untouchable" and move on. Keep in mind that with the passage of time more and more flights are coming into the picture. Attila will work these flights around the "untouchable" flights to get the most out of the airspace.
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What does Attila do during irregular operations?

Using Attila, an airline can expect a later entry into, and less severe "irregular operations". Once in an irregular operation, Attila does the same thing it does during regular operations. It calculates an optimum time for each aircraft to arrive at the runway. Obviously, during irregular operations, it may not be possible to generate a solution for all airborne aircraft due to capacity limitations, but the information provided by Attila can is also very useful. For example, Attila gives the airline the predicted queue and the position of each aircraft in the queue. If the aircraft is expected to hold for 30 minutes, and the aircraft has only 20 minutes of fuel, it makes little sense to wait for 20 minutes and then divert. Having this information well ahead of time let you make aircraft by aircraft decisions about holding versus alternate airports.
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Our flights are already on time, how can Attila help?

If your flights are on time, and your block times are near ideal, Attila will "only" save $10,000 to $30,000 a day in fuel. If, on the other hand your block times are now really 5%, 10% or 20% more than they were 20 to 30 years ago, then we need to talk. Not only can Attila save fuel, it can also help you shave off some of this block time, while improving the airline's on time performance.
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How much of a change will Attila make to each aircraft?

The maximum change that Attila will make to an individual aircraft will typically be below the range of 5% of current cruise speed or 10 knots as specified in the Aeronautical Information Manual. Additionally, the amount of change requested by each aircraft is a Company policy decision that is easily configurable with in the Attila software.
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This is a big problem. How can such small changes make a difference?

Attila is a 24/7 operation. It looks at every flight and makes a small adjustment to each flight. By making hundreds of small adjustments day in and day out, Attila provides significant benefit. For example, when an airport is at or near capacity, given the random flow of aircraft queuing theory and ATH Group's analysis shows that the arrival queue increases exponentially. This is because once capacity is reached, ATC has only one option. That option is to de-peak the flow backward in time by adding more and more delay to each successive aircraft. Conversely, by acting sooner in the arrival flow, Attila identifies the aircraft at the head of the queue and moves those aircraft forward in time, even if those aircraft are ahead of schedule. Speeding up even a few aircraft at the head of the queue into what would have been wasted landing slots pulls the entire queue forward. In other words, moving 2 aircraft off the front end of the queue of 30 aircraft doesn't save 2 minutes; it saves 2 minutes times every aircraft in the queue behind those 2 flights. In this case dropping 60 minutes from the actual arrival flow. This recapturing of unused slots forward in time is a very powerful near term benefit, which begins the very first day Attila is operational. Secondly, better organization of the arrival queue behind the first few aircraft reduces the variance of the arrival flow and provides the ATC a more solvable problem. This requires less vectoring, and therefore less flight time. Again a day 1 benefit. Without the Attila feedback control mechanism an unused landing slot is gone forever. We call it the cascade effect because each of these lost opportunities affects all aircraft behind it, sometimes for the rest of the day. Have a look at our Attila Scoreboard to see how it has been doing.
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How many messages will Attila send each aircraft?

Usually just one, but this is a matter of company policy. There are times when a second message could improve the solution. In those cases, Attila may send two messages during a flight if the company policy allows. We are very aware of not overloading the pilot with marginal information.
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How will our pilots calculate the new arrival time?

Pilots have been trained since the beginning of flight to do distance, speed versus time calculations. Obviously, having a Flight Management Computer (FMC) in the aircraft makes meeting the Attila time is easier. Many aircraft allow entry of a specified time at the arrival fix (RTA). With this RTA function, all the pilot need do is enter the fix time sent by Attila. Even with a non-FMS aircraft, given the accuracy of the flight plans, meeting the Attila time within +/- 30 seconds is reasonable. Military pilots routinely practice "time on target" operations within seconds. This is not a new task for pilots. For more information go to the Pilots Section.
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Avionics are tremendously expensive, what new gear do I need to put on my airframes?

No new gear is required on any aircraft.
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How difficult is the system to operate?

Once it is set up, the system is almost fully automated. The system will calculate solutions and send messages to each aircraft on its own. It is only necessary to monitor the process to insure its correct operation and to adjust input parameters such as airport arrival rate or goal scenario. On some days you may wish to optimize fuel more strongly, or other days schedule or gate availability might be more important.
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I can see how this could work for my hubs, but what about non-hub airports?

In airports that you do not hub, it is still very valuable to know where you fit within the queue. If a small change can put even a single aircraft at the head of a queue, versus the end of a queue, it will save you minutes. These minutes may very well make the difference in these particular aircraft being on time or late for the rest of the day.
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