Patent Publication Number: US-11392867-B2

Title: Automated buffer setting

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of co-pending U.S. application Ser. No. 14/500,447, filed on Sep. 29, 2014, and which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     Aspects described herein relate to personnel scheduling, and more specifically, to preparing schedules of tasks for personnel based on a likelihood that the schedules of tasks will not exceed a personal limit of a person assigned to the itinerary and/or based on priority rankings for the tasks. 
     SUMMARY 
     According to one aspect, a computer-implemented method. The method includes retrieving from an electronic data source a plurality of tags relating to past instances of a plurality of various operations, each tag including a first symbol representing a magnitude of time variance for a respective operation of the various operations and a second symbol representing a likelihood of time variance for the respective operation. The method further includes parsing the plurality of tags and determining a plurality of predicted time variances, including at least one predicted time variance for each of the various operations based on the plurality of tags and a selected reliability factor. The method further includes selecting a first predicted time variance for a first operation, from among the plurality of predicted time variances, based on a reliability factor. The method further includes identifying a combination of operations, including the first predicted time variance, and determining a likelihood that the combination of operations does not exceed at least one personal limit of personnel. The method further includes generating an itinerary that includes the identified combination of operations. The method further includes automatically tasking personnel to perform the operations of the generated itinerary. 
     According to one aspect, a system including a processor and a memory storing a program, which, when executed on the processor, performs an operation. The operation includes retrieving from an electronic data source a plurality of tags relating to past instances of a plurality of various operations, each tag including a first symbol representing a magnitude of time variance for a respective operation of the various operations and a second symbol representing a likelihood of time variance for the respective operation. The operation further includes parsing the plurality of tags and determining a plurality of predicted time variances, including at least one predicted time variance for each of the various operations based on the plurality of tags and a selected reliability factor. The operation further includes selecting a first predicted time variance for a first operation, from among the plurality of predicted time variances, based on a reliability factor. The operation further includes identifying a combination of operations, including the first predicted time variance, and determining a likelihood that the combination of operations does not exceed at least one personal limit of personnel. The operation further includes generating an itinerary that includes the identified combination of operations. The operation further includes automatically tasking personnel to perform the operations of the generated itinerary. 
     According to one aspect, a computer program product including a computer-readable storage medium having computer-readable program code embodied therewith, the computer-readable program code executable by one or more computer processors to perform an operation. The operation includes retrieving from an electronic data source a plurality of tags relating to past instances of a plurality of various operations, each tag including a first symbol representing a magnitude of time variance for a respective operation of the various operations and a second symbol representing a likelihood of time variance for the respective operation. The operation further includes parsing the plurality of tags and determining a plurality of predicted time variances, including at least one predicted time variance for each of the various operations based on the plurality of tags and a selected reliability factor. The operation further includes selecting a first predicted time variance for a first operation, from among the plurality of predicted time variances, based on a reliability factor. The operation further includes identifying a combination of operations, including the first predicted time variance, and determining a likelihood that the combination of operations does not exceed at least one personal limit of personnel. The operation further includes generating an itinerary that includes the identified combination of operations. The operation further includes automatically tasking personnel to perform the operations of the generated itinerary. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1A  is a block diagram illustrating an exemplary duty schedule for a pilot over a two-day period; 
         FIG. 1B  is a block diagram illustrating an exemplary duty period for a pilot in which the pilot is scheduled to perform four flight segments during the duty period; 
         FIG. 1C  is a block diagram illustrating an exemplary duty period for a pilot in which the pilot is scheduled to perform four flight segments, but the fourth flight segment would exceed the pilot&#39;s duty period; 
         FIG. 2A  is an exemplary data table for past instances of a flight segment illustrating a method for determining reliability factors for operating time variances, wherein the operating time variance is an arrival time variance; 
         FIG. 2B  is an exemplary data table for past instances of a flight segment illustrating a method for determining reliability factors for operating time variances, wherein the operating time variance is a block time variance; 
         FIG. 3  is a block diagram of a method for assigning future instances of flight segments to crew itineraries; 
         FIG. 4  is a block diagram illustrating flight crews of inbound flight segments being assigned to outbound flight segments based on a “first in first out” process; 
         FIG. 5A  is an exemplary data table that illustrates a method for assigning a priority to different flight segments; 
         FIG. 5B  is an exemplary table that illustrates acceptable reliability factors or risk levels associated with different priorities; 
         FIG. 6  is a block diagram illustrating flight crews of inbound flight segments being assigned to outbound flight segments based on a “first in to highest priority” process; 
         FIG. 7A  is block diagram of a method for assigning future instances of flight segments to combinations of flight segments based on a likelihood that a combination will cause a pilot assigned to the combination to exceed a personal limit and based on a priority of the flight segment; and 
         FIG. 7B  is a block diagram of a method for assigning pilots to future instances of flight segments based on a priority of the flight segment and based on pilots having the highest available personal limits. 
     
    
    
     DETAILED DESCRIPTION 
     In various industries, assigning personnel (e.g., employees) to tasks or jobs can be limited by personal limits for the personnel. For example, commercial airline pilots have several different personal limits related to the length of time they can be on duty that can limit how the pilots can be assigned to different flight segments. 
       FIG. 1A  illustrates a two-day timeline  102  of an exemplary duty scenario  100  for a pilot of commercial aircraft. In the scenario  100 , the pilot has a first duty period  104   a  during a first day and a second duty period  104   b  during a second day. The first duty period  104   a  and the second duty period  104   b  are separated by a rest period  106 . Government regulations (e.g., Federal Aviation Administration regulations), airline regulations, union rules, and the like may dictate personal limits for how long the duty periods  104   a  and  104   b  can be and may also dictate how long the rest period  106  between the two duty periods  104   a  and  104   b  needs to be. 
       FIG. 1B  provides a more detailed view of an exemplary duty period  104  for a pilot. In the exemplary duty period  104 , the pilot has been assigned to an itinerary of four flight segments  108   a ,  108   b ,  108   c , and  108   d  (collectively, flight segments  108 ). Each of the flight segments  108  defines a block time, which is an elapsed time from when an aircraft is pushed back from a gate at a departure airport to when the aircraft stops at a gate at an arrival airport. Again, government regulations, airline regulations, union rules, and the like can dictate personal limits for how much block time a pilot can accumulate during a duty period  104  and how long the pilot can be on duty. 
     As shown in  FIG. 1B , the duty period  104  can begin at an earlier time than the first flight segment  108   a . As an illustration, a pilot may begin his duty period  104  when he arrives at the airport at 6:00 AM. However, the pilot&#39;s first flight segment may not depart the gate until 6:45 AM. In such an instance, a time gap  110   a  of forty five minutes exists between the beginning of the pilot&#39;s duty period  104  and the beginning of the block time for the first flight segment  108   a . Similarly, the pilot may need time between flight segments to travel from a first aircraft to a second aircraft, review the flight plan for the next flight segment, etc. Thus, time gaps  110   b ,  110   c , and  110   d  are inserted between flight segments  108  to allow for such pilot transitions. The length of the time gaps  110   b ,  110   c , and  110   d  that may be needed for pilots to transition can vary depending on the airport, time of day, time of year, etc. For example, at a large, busy airport such as O&#39;Hare International Airport in Chicago Ill., a pilot may need an hour or more to transition from a first aircraft after flying a first flight segment to a second aircraft for a second flight segment. At a smaller, less-congested airport, a pilot may only need a half-hour to transition from a first aircraft after flying a first flight segment to a second aircraft for a second flight segment. As another example, on a weekday morning when airports are busy, a pilot may need more time to transition from a first flight segment to a second flight segment than may be needed on a weekend afternoon when the airport may be less crowded. 
     Ideally, a pilot&#39;s duty period  104  includes a time gap  110   e  between the end of his last flight segment  108   d  and the end of the duty period  104 . Such a time gap  110   e  can ensure that the pilot does not exceed his total duty time on the last flight segment.  FIG. 1C  illustrates an exemplary duty period  104  for a pilot in which the last flight segment  108   d  is delayed in departing. As a result, if the pilot performed the fourth flight segment, he would exceed his allowable duty time. For example, referring again to  FIG. 1C , if the fourth flight segment  108   d  is delayed such that the aircraft will not arrive at the gate before the pilot&#39;s duty period  104  ends, then the pilot cannot fly the flight segment  108   d , and a different pilot has to perform the flight segment. By contrast, if the fourth flight segment  108   d  takes off on time (as shown in  FIG. 1B ) but is delayed in the air (e.g., by weather) such that the aircraft does not arrive at the gate until after the pilots duty period  104  ends, such an inadvertent overage of the pilot&#39;s personal limits is permissible. 
     An operation can have one or more personnel time limit criteria associated with it. Continuing the examples above, a flight segment may have several personnel time limit criteria, such as personnel time limit criteria related to block time, arrival time, and connection time. The personnel time limits may be different based on a priority of an operation. Continuing the examples above, a particular flight segment may have a block time of two hours and thirty minutes. A personnel time limit criterion related to block time can be set to two hours and thirty minutes. If the flight becomes a high priority flight segment, then the personnel time limit criterion related to block time may be increased to three hours. 
     To avoid exceeding the personal limits of pilots, airlines can employ buffers to account for operating variances. For example, airlines may add an hour of extra block time to a duty period when scheduling the crew to decrease the likelihood that the crew will actually exceed their personal limits. Similarly, an airline may require a minimum connection time (by adding a connection time buffer between flight segments) of an hour and a half regardless of the airport, the time of day, the time of year, or the like. These buffers are often set to a conservative number that will capture most flight operations. However, a significant number of flight operations do not require such large buffers. As a result, significant amounts of crew time can be wasted by these buffers. For example, if the pilot is only allowed eight hours of block time during any given duty period  104 , then an hour of block time buffer only allows the pilot to be scheduled to fly seven actual block hours. 
     For commercial airline operations, a flight segment may be defined as an operation scheduled to depart a first airport at a specific time of day (and possibly a day of the week) and arrive at a second airport at a second specific time of day. For example, an airline may operate hourly flight segments between LaGuardia Airport in New York City and Reagan national Airport in Washington D.C. The flight segment leaving LaGuardia at 7 AM each day is considered a first flight segment, a flight segment leaving LaGuardia at 8 AM each day is considered a second flight segment, etc. Often, an airline will use the same numerical indicator (e.g., Oceanic 1140 or Oceanic 3288) for the same flight segment on each day. However, airlines sometimes treat weekend flight segments differently than weekday flight segments because airlines may fly different schedules on the weekends and/or air traffic congestion may be reduced. For example, a flight segment from LaGuardia to Reagan National may take one hour gate to gate during the week due to air traffic and the like. However, the same flight segment may only take fifty minutes on the weekend. 
     Aspects described herein analyze historical data for different flight segments to determine the likelihood of various flight operation variances. These flight operation variances can be used to add buffers that are flight segment specific. These flight segment specific buffers can be more accurate than generally-applied buffers, meaning that such a buffer applied to a specific flight segment can be an accurate representation of actual variations from scheduled operation.  FIGS. 2A and 2B  illustrate exemplary data for a month that may be used to analyze flight operation variances for a particular flight segment.  FIG. 2A  illustrates a data table  200  for a particular flight segment that is scheduled to arrive at a destination airport at 11:50 AM (denoted as  1150  in column  206  of the data table  200 ), wherein a first column  202  indicates the thirty days in the particular month. A second column  204  indicates the day of the week associated with each of the thirty days of the month. The third column  206  indicates the actual arrival time of the flight segment on each of the thirty days of the month. For example, on the first day of the month, the flight segment arrived at 11:49 AM; one minute early. On the second day of the month, the flight segment arrived at 11:41 AM; nine minutes early. On the third day of the month, the flight segment arrived at 11:50 AM; on time. On the fourth day of the month, the flight segment arrived at 11:58 AM; eight minutes late. The fifth column  210  of the data table  200  provides a ranking of the nine most-delayed operations of the flight segment over the course of the month. For example, the flight segment on the twelfth day (in row  218 ) arrived at 12:25 PM, which is 35 minutes late. This flight segment was the most delayed over the course of the month and is therefore ranked number one in the rank column  210 . The flight segment on the eleventh day (in row  220 ) arrived at 12:20 PM, which is 30 minutes late. This flight segment was the second most-delayed flight segment over the course of the month and is therefore ranked number two in the rank column  210 . Similarly, the flight segment on the ninth day of the month (row  222 ) was the third-most delayed flight segment of the month, the flight segment on the nineteenth day of the month (row  224 ) was the fourth-most delayed flight segment of the month, the flight segment on the fourth day of the month (row  226 ) was the fifth-most delayed flight segment of the month, the flight segment on the twenty-fifth day of the month (row  228 ) was the sixth-most delayed flight segment of the month, the flight segment on the twenty-third day of the month (row  230 ) was the seventh-most delayed flight segment of the month, the flight segment on the eighth day of the month (row  232 ) was the eighth-most delayed flight segment of the month, and the flight segment on the twenty-second day of the month (row  234 ) was the ninth-most delayed flight segment of the month. These flight segments are ranked three, four, five, six, seven, eight, and nine, respectively, in column  210 . 
     With rankings determined, likelihoods of the flight segment arriving late (e.g., a predicted arrival time or predicted arrival time variance) can be determined. Using the exemplary thirty flight segments shown in  FIG. 2A , a flight segment on a particular day represents approximately 3% of the total flight segments. As discussed above, in this example, the worst flight segment of the month on the twelfth day (row  218 ) arrived 35 minutes late. Thus, 97% of the flight segments during the month arrived no more than 34 minutes late. If an airline wants to establish a buffer for the arrival time for this particular flight segment that has a 97% reliability factor, then the airline could establish a buffer of 34 minutes. Alternatively, if the airline wants to establish a buffer for the arrival time for this particular flight segment that has a 97% reliability factor, then the airline could establish a buffer of 30 minutes (equal to the next longest flight) or any time between 30 minutes and 34 minutes. Continuing the example, the second worst flight segment of the month on the eleventh day (row  220 ) arrived 30 minutes late and the third worst flight segment of the month on the ninth day (row  222 ) arrived 20 minutes late. The first, second, and third worst flight segments together represent approximately 10% of the total flight segments for the month. Thus, 90% of the flight segments during the month arrived no more than 19 minutes late. If an airline wants to establish a buffer for the arrival time for this particular flight segment that has a 90% reliability factor, the airline could establish a buffer of 19 minutes. Continuing the example again, the fourth worst flight segment of the month on the nineteenth day (row  224 ) arrived 18 minutes late, the fifth worst flight segment of the month on the fourth day of the month (row  226 ) arrived eight minutes late, and the sixth worst flight segment of the month on the twenty-fifth day (row  228 ) arrived six minutes late. The first through sixth worst flight segments together represent approximately 20% of the total flight segments for the month. Thus, 80% of the flight segments during the month arrived no more than five minutes late. If an airline wants to establish a buffer for the arrival time for this particular flight segment that has an 80% reliability factor, the airline could establish a buffer time of five minutes. 
       FIG. 2B  illustrates a data table  250  for a particular flight segment that is scheduled to have a block time of two hours and thirty minutes (denoted as 2:30 in column  256  of the table  250 ), wherein a first column  252  indicates the thirty days in a particular month. A second column  254  indicates the day of the week associated with each of the thirty days of the month. The third column  256  indicates the actual block time of the flight segment on each of the thirty days of the month. For example, on the first day of the month, the block time was two hours and twenty nine minutes; one minute short. On the second day of the month, the block time was two hours and twenty one minutes; nine minutes short. On the third day of the month, the block time was two hours and thirty minutes; on time. On the fourth day of the month, the block time was two hours and thirty eight minutes; eight minutes long. The fifth column  260  of the table  250  provides a ranking of the nine longest block times for the flight segment over the course of the month. For example, the block time for the flight segment on the twelfth day (in row  268 ) was three hours and five minutes, which is 35 minutes long (relative to the scheduled two hours and thirty minutes). This flight segment was the longest over the course of the month and is therefore ranked number one in the rank column  260 . The block time for the flight segment on the eleventh day (in row  270 ) was three hours, which is thirty minutes long. This flight segment was the second longest over the course of the month and is therefore ranked number two in the rank column  260 . Similarly, the block time for the flight segment on the ninth day of the month (row  272 ) was the third longest of the month, the block time for the flight segment on the nineteenth day of the month (row  274 ) was the fourth longest of the month, the block time for the flight segment on the fourth day of the month (row  276 ) was the fifth longest of the month, the block time for the flight segment on the twenty-fifth day of the month (row  278 ) was the sixth longest of the month, the block time for the flight segment on the twenty-third day of the month (row  280 ) was the seventh longest of the month, the block time for the flight segment on the eighth day of the month (row  282 ) was the eighth longest of the month, and the block time for the flight segment on the twenty-second day of the month (row  284 ) was the ninth longest of the month. These flight segments are ranked three, four, five, six, seven, eight, and nine, respectively, in column  260 . 
     With rankings determined, likelihoods of the block time for the flight segment being longer than scheduled (i.e., a predicted block time variance) can be determined. Using the exemplary thirty flight segments shown in  FIG. 2B , a flight segment on a particular day represents approximately 3% of the total flight segments. As discussed above, in this example, the block time for the worst flight segment of the month on the twelfth day (row  268 ) was 35 minutes longer than scheduled. Thus, the block time for 97% of the flight segments during the month was no more than 34 minutes long. If an airline wants to establish a buffer for the block time for this particular flight segment that has a 97% reliability factor, then the airline could set a buffer of 34 minutes. Alternatively, if the airline wants to establish a buffer for the block time for this particular flight segment that has a 97% reliability factor, then the airline could establish a buffer of 30 minutes (equal to the next longest flight) or any time between 30 minutes and 34 minutes. Continuing the example, the block time for the second worst flight segment of the month on the eleventh day (row  220 ) was 30 minutes longer than scheduled and the block time for the third worst flight segment of the month on the ninth day (row  222 ) was 20 minutes longer than scheduled. The first, second, and third worst flight segments together represent approximately 10% of the total flight segments for the month. Thus, the block time for 90% of the flight segments during the month was no more than 19 minutes longer than scheduled. If an airline wants to establish a buffer for the block time for this particular flight segment that has a 90% reliability factor, the airline could set a buffer of 19 minutes. Continuing the example again, the block time for the fourth worst flight segment of the month on the nineteenth day (row  224 ) was 18 minutes longer than scheduled, the block time for the fifth worst flight segment of the month on the fourth day of the month (row  226 ) was eight minutes longer than scheduled, and the block time for the sixth worst flight segment of the month on the twenty-fifth day (row  228 ) was six minutes longer than scheduled. The first through sixth worst flight segments together represent approximately 20% of the total flight segments for the month. Thus, the block time for 80% of the flight segments during the month was no more than five minutes longer than scheduled. If an airline wants to establish a buffer for the block time for this particular flight segment that has an 80% reliability factor, the airline could set a buffer time of five minutes. 
     The tables in  FIGS. 2A and 2B  are provided for illustration purposes. In various instances, larger data sets could be used to provide more robust analyses. For example, if the data set includes 100 flight segments, then a flight segment on a particular day represents 1% of the total flight segments, and the airline may be able to select buffers with 99% reliability factors. As another example, if the data set includes 1000 flight segments, then 10 flight segments represents 1% of the total flight segments. Here, the airline could select buffers with 99.9% reliability factors. Additionally, larger data sets may reveal outlier instances more readily. For example, referring again to  FIG. 2A , the flight segments on the twelfth the day of the month (row  218 ) arrived 35 minutes late. Based on the data shown in  FIG. 2A , 3% of the flight segments would be expected to arrive 35 minutes late. As described above, a buffer of thirty four minutes can be set with a 97% reliability factor. However that data point on the twelfth day may be an outlier such that if 1000 flight segments are looked at, only two or three flight segments are 35 minutes late in such an instance, the 34 minutes buffer would not represent a 97% reliability factor. Rather, the 34 minute buffer would represent a greater than 99% reliability factor. 
     Additional likelihoods can be determined in a similar manner to arrival time and block time as explained above with reference to  FIGS. 2A and 2B . 
     The data in the data tables  200  and  250  in  FIGS. 2A and 2B , respectively, can also be parsed and analyzed based on additional factors. For example, as discussed above, commercial flight segments generally do not experience the same delays on weekends that may be experienced during weekdays because there are generally fewer flight segments on weekends. Thus, the type of data shown in the data tables  200  and  250  can be split into weekday flight segments and weekend flight segments, and separate analyses can be performed on the different sets of data, for example. The type of data shown in the data tables  200  and  250  could also be split by day of the week, and separate analyses can be performed on the different sets of data. 
     In various aspects, the data or reliability factors can be represented by tags. For example, a tag may include a combination of a letter and a number. The letter can represent a magnitude of a variance and the number can represent a likelihood of the variance for a particular flight segment. For example, for an arrival delay (a variance from the scheduled arrival time), the letter “A” may represent a delay of five minutes or less. The letter “B” may represent a delay of fifteen minutes or less. The letter “C” may represent a delay of thirty minutes or less. The letter “D” may represent a delay of an hour or less. The letter “E” may represent a delay of two hours or less. The letter “F” may represent a delay of greater than two hours. Furthermore, the number “1” may represent a 99% likelihood that the associated delay is not exceeded. The number “2” may represent a 97% likelihood that the associated delay is not exceeded. The number “3” may represent a 95% likelihood that the associated delay is not exceeded. The number “4” may represent a 90% likelihood that the associated delay is not exceeded. The number “5” may represent an 85% likelihood that the associated delay is not exceeded. The number “6” may represent an 80% likelihood that the associated delay is not exceeded. Thus, for example, a particular flight segment may include the tag “B3,” which would mean that the flight segment is delayed by fifteen minutes or less 95% of the time. Another flight segment may include the tag “B4,” which would mean that the flight segment is delayed by fifteen minutes or less 90% of the time. A flight segment may include more than one tag. For example, a flight segment may include a first tag “A6” and a second tag “B4,” meaning that the flight segment is delayed five minutes or less 80% of the time and is delayed by fifteen minutes or less 90% of the time. The flight segment may have other tags related to different operating variances, such as block time variances. 
     Referring again to  FIGS. 1A and 1B , when determining combinations of flight segments that can form an itinerary, aspects described herein can add the determined buffers to the various flight segments in the combination, based on an acceptable reliability factor. In various instances, the acceptable reliability factor may be the same for every flight segment operated by a particular airline. As discussed in greater detail below, in various instances, different reliability factors may be applied to different flight segments operated by an airline. For example, an airline may use a 99% reliability factor for high priority flight segments (e.g., flight segments that are important to customers, flight segments that generate high revenues, flight segments that are strategically important, and/or flight segments that return an aircraft to a maintenance facility), and buffers for the high priority flight segment can be automatically set based on the analysis, described above, and the 99% reliability factor. As another example an airline may use a 97% reliability factor for medium priority flight segments, and buffers for the medium priority flight segment can be automatically set based on the analysis, described above, and the 97% reliability factor. As another example, an airline may use a 95% reliability factor for low priority flight segments, and buffers for the low priority flight segment can be automatically set based on the analysis, described above, and the 95% reliability factor. In the event that a combination of flight segments (with the determined buffers applied) would exceed a personal duty time limit for a pilot, then the combination of flight segments would be rejected (i.e., an itinerary would not be formed from that combination). For example, referring to  FIG. 1B , if a possible combination of flight segments has a pilot flying four flight segments  108   a ,  108   b ,  108   c , and  108   d , and the predicted block time for the combination of flight segments (when the buffers for the flight segments are included) would exceed a pilot&#39;s total block time, then the combination is not workable. As a result, the combination would not be assigned to an itinerary. Instead, the combination could be changed to include a different flight segment that has a shorter block time than flight segment  108   d . Alternatively, the combination could be changed to include different earlier flight segments so that the combination can include flight segment  108   d.    
       FIG. 3  illustrates a process  300  that aspects described herein can use to assign combinations of flight segments to itineraries. In block  302  of the process  300 , historical operational data for the various flight segments can be retrieved. For example, historical operational data, such as the type of data shown in  FIGS. 2A and 2B , for flight segment  108   d  (in  FIG. 1B ) may be retrieved. In block  304  of the process  300 , an analysis on the retrieved data can be performed to determine the likelihood&#39;s of various flight operation variances. For example, the analysis may determine the likelihood that the flight segment  108   d  arrives five minutes late, the likelihood that the flight segment  108   d  arrives 10 minutes late, etc. As discussed, one or more tags can be applied to the analysis for flight segment  108   d  as a result of the analysis. As another example, the analysis may determine the likelihood that the block time for the flight segment  108   d  is five minutes longer than scheduled, the likelihood that the block time for the flight segment  108   d  is 10 minutes longer than scheduled, etc. Again, one or more tags can be applied to the analysis for flight segment  108   d . In block  306  of the process  300 , an acceptable likelihood (i.e., reliability factor) can be determined. As described above, in various aspects, a single reliability factor can be applied to all operation variances for all flight segments. In various other aspects, different reliability factors can be applied to different flight segments and/or to different operation variances. For example, a first reliability factors could be applied to an operation variances related to block time and a second reliability factors could be applied to an operation variances related to arrival time. In block  308 , a combination of flight segments (with buffers having reliability factors applied) that do not exceed personal limits of pilots (e.g., block time limits and total duty time limits) is identified. In block  310 , the identified combination of flight segments is assigned to an itinerary. 
     Other flight segments can be formed into other combinations of flight segments and assigned to itineraries in a similar manner until all of the flight segments for an airline for a particular period (e.g., a day, a week, or a month) are assigned to itineraries. Pilots can then be assigned to the various itineraries. In various instances, itineraries may not be optimized at an individual level, but the schedule of itineraries may be optimized. Put differently, an individual pilot&#39;s itinerary may not be optimized (e.g., it may not utilize as much of his block time as possible), but the itineraries may provide an overall optimized schedule for the airline&#39;s operations. 
     Aspects of systems and/or computer program products that perform the process  300  of  FIG. 3  may provide a user interface that enables a user (e.g., a crew scheduler) to select the reliability factors for different flight segments or groups of flight segments (e.g., high priority flight segments, medium priority flight segments, and low priority flight segments). The setting of buffers for the flight segments based on the analysis and selected reliability factors may be invisible to the user. Put differently, the user may select a reliability factor for a flight segment (or group of flight segments), and the system and/or computer program would update and output relevant times for the flight segment (e.g., block time and arrival time) based on the analysis of past instances of the flight segment and the selected reliability factor. 
     In various instances, any combination of flight segments can be assigned to any itinerary. Continuing the example above, a first possible combination of flight segments could be predicted to leave a pilot with two hours and fifty-five minutes of available block time by the time he would fly flight segment  108   d . A second possible combination of flight segments could be predicted to leave a pilot with three hours of available block time by the time he would fly flight segment  108   d . Flight segment  108   d  could be included in either the first possible combination or the second possible combination. However, the additional available block time in the second combination of flight segments provides an extra buffer compared to the first combination of flight segments. For example, if an earlier flight segment in the first and second combinations has a block time of ten minutes longer than expected (even with a buffer applied), then the first combination only leaves the pilot with two hours and forty five minutes of block time available for flight segment  108   d —less than the two hours and forty-nine minutes with the reliability factor described above. By contrast, the second combination of flight segments would have still leave the pilot with two hours and fifty minutes of available block time—still more than the two hours and forty-nine minutes. In such an exemplary instance, assigning flight segment  108   d  to the second combination of flight segments can be a less-risky option than assigning flight segment  108   d  to the first combination. For an airline that may operate hundreds or thousands of flight segments every day at different times and from different airports, it is likely that some flight segments will have a riskier crew scheduling than others. As described in greater detail below, if an airline can identify a certain subset of flight segments that are considered to be high priority, then the least risky crew assignments can be assigned to those flight segments. Similarly, the most risky crew assignments (e.g., crew assignments that are more at risk of causing a flight delay or cancellation due to the flight segment exceeding personal limits of the pilot(s)) can be assigned to low priority flight segments. 
       FIG. 4  illustrates a timeline for an exemplary scenario  400  in which four flight segments  408 ,  410 ,  412 , and  414  are arriving at Hartsfield International Airport in Atlanta  402  shortly before noon (represented by dashed line  404 ) and four flight segments  416 ,  418 ,  420 , and  422  are leaving Atlanta  402  little after 1:00 PM (represented by dashed line  406 ). For the purposes of illustration, in this scenario  400 , the possible combinations of flight segments for the flight crews for the four incoming flight segments  408 ,  410 ,  412 , and  414  include assignments to one of the four outgoing flight segments  416 ,  418 ,  420 , and  422 . In this scenario  400 , the priorities of the four outgoing flight segments  416 ,  418 ,  420 , and  422  are not known. As a result, the crews from the inbound flight segments could be assigned to the outbound flight segments based on a modified first in first out basis. The first pilots into Atlanta  402  are assigned to the first flight segment out of Atlanta, except a few modifications are made based on flight segments that are more likely to be substantially delayed. For example, flight segment  408  is scheduled to arrive in Atlanta first at 11:50 AM. However, the flight segment  408  is historically late by 30 minutes or more 5% of the time. The remaining flight segments  410 ,  412 , and  414  arrive later but are only 30 minutes late 1% or 2% of the time. Thus, even though flight segment  408  is scheduled to arrive first, for scheduling purposes its crew is treated as if they arrive last due to the significantly more likely possibility that flight segment  408  will arrive at least 30 minutes late. Otherwise, the combination of flight segments for the crew of flight segment  410 , which is scheduled to arrive in Atlanta  402  at 11:53 AM, next includes flight segment  416  (as denoted by dashed arrow  426 ), which departs Atlanta  402  at 1:00 PM. Similarly, the combination of flight segments for the crew of flight segment  412 , which is scheduled to arrive in Atlanta  402  at 11:55 AM, next includes flight segment  418  (as denoted by dashed arrow  428 ), which departs Atlanta  402  at 1:01 PM. Also, the combination of flight segments for the crew of flight segment  414 , which is scheduled to arrive in Atlanta  402  at 11:55 AM, next includes flight segment  420  (as denoted by dashed arrow  430 ), which departs Atlanta  402  at 1:06 PM. Finally, the combination of flight segments for the crew of flight segment  408 , which is scheduled to arrive in Atlanta  402  at 11:50 AM (but which has a significantly higher likelihood of being late by 30 minutes or more), next includes flight segment  422  (as denoted by dashed arrow  424 ), which departs Atlanta  402  at 1:10 PM. 
     The above-described assignment of flight crews to various aircraft in Atlanta  402  may result in a relatively even distribution of schedule risk for the four departing flight segments  416 ,  418 ,  420 , and  422 . However, if one of the departing flight segments is of a higher priority than the others it may be advantageous to rearrange the crew assignments so that the highest priority flight segment has less scheduling risk. 
       FIG. 5A  illustrates a table  500  with exemplary data that is used to assign priorities to different flight segments. A first column  502  of the table  500  identifies ten flight segment numbers. Although these flight segment numbers are illustrated herein as the numbers  1  through  10 , the numbers could correspond to flight segment numbers used by an airline. Columns  504  and  506  of the table  500  identify the departure airport and arrival airport, respectively, for the flight segments. Columns  508  through  514  of the table  500  identify various different exemplary priority rankings for the flight segments that can be used to determine an overall priority ranking (in column  516 ). Column  508  identifies a market value (e.g., revenue) for the flight segments. Column  510  identifies a financial ranking for the flight segments (on a scale of 1 to 5 where 1 is a high ranking and 5 is a low ranking). In various instances, the financial ranking may be correlated to or otherwise associated with the market value in column  510 . For example, flight segment number two and flight segment number eight have a market value (in column  508 ) of $110,000 and a corresponding financial ranking of 1. By contrast flight segment number four has a market value of $20,000 and a corresponding financial ranking of 5. In various instances, the financial rankings may not correlate or otherwise correspond to the market values. In such instances, the financial rankings may be entered or modified (e.g., by a system administrator) to reflect a “subjective” financial ranking to the airline. Column  512  identifies a maintenance ranking for the flight segments (on a scale of 1 to 5 where 1 is high ranking and 5 is low ranking). Airlines often maintain maintenance facilities at certain airports that they fly to or from. The flight segments flying to those airports may be high priority for maintenance reasons (e.g., if an aircraft is due for maintenance, service, or an inspection). For example, flight segment  7  in the table  500  is scheduled to arrive at Denver international Airport. In this exemplary scenario, Denver may be a maintenance facility for this particular airline. Consequently, this flight segment may have a maintenance ranking of 1 (e.g., if the aircraft is due for scheduled maintenance). The remaining nine flight segments do not arrive at Denver and therefore have a maintenance ranking of 5. Column  514  identifies a strategic ranking for the flight segments (on a scale of 1 to 5 where 1 is high ranking and 5 is low ranking). A flight segment may be high priority for reasons other than revenue or maintenance. For example, a particular airline may be pursuing a marketing initiative in which they advertise hourly flight segments from LaGuardia Airport in New York City to Reagan National Airport in Washington, D.C. to attract business travelers. Some of the hourly flight segments may not be particularly profitable or may even lose money. However, those flight segments would be important for the marketing efforts of the company. As another example, a particular flight segment may fly between two hub airports for an airline. Such a flight segment may be strategically high priority because the cancellation or delay of the flight segment could result in a cascade of subsequent missed connections or flight segments for passengers. By contrast, a low revenue flight segment into a small market may have low strategic priority. Additional rankings may be provided on any number of factors that an airline finds to be important. In column  516  of the table  500 , an overall ranking can be calculated based on the individual rankings. For example, in the table  500 , the financial ranking (in column  510 ), the maintenance ranking (column  512 ), and the strategic ranking (column  514 ) are averaged together to determine the overall ranking for the flight segments. Alternatively, the various rankings could be added together, averaged using a weighted average, or the like. 
     Referring now to  FIG. 5B , different buffer reliability factors can be assigned to flight segments having different overall rankings (e.g., from the table shown  500  shown in  FIG. 5A ). For example,  FIG. 5B  illustrates a table  530  of different reliability factors for buffers for different overall rankings. The first column  532  of the table  530  includes different ranges of overall rankings. For example, overall rankings between 1 and 2.5 can be considered high priority flight segments, overall rankings between 2.6 and 3.5 can be considered medium priority flight segments, and overall rankings between 3.6 and 5 can be considered low priority flight segments. The ranges of overall ranking may be associated with different reliability factors for buffers associated with different operation variances. For example, column  534  of the table  530  identifies allowable reliability factors for block time buffers. For example, for high-priority flight segments, a block time buffer must provide at least a 99% reliability factor. For medium priority flight segments a block time buffer must provide at least a 98% reliability factor. For low priority flight segments, a block time buffer must provide at least a 97% reliability factor. As another example, column  536  of the table  530  identifies allowable reliability factors for duty time buffers (e.g., buffers designed to prevent a crew member from exceeding total duty time limits). For example, for high-priority flight segments, a duty time buffer must provide at least a 98% reliability factor. For medium priority flight segments, a duty time buffer must provide at least a 97% reliability factor. For low priority flight segments, a duty time buffer must provide at least a 96% reliability factor. As another example, column  538  of the table  530  identifies allowable reliability factors for rest time (e.g., the amount of time a pilot must be off-duty between on duty periods). For example, for high-priority flight segments, the rest time buffer must provide at least a 99% reliability factor. For medium priority flight segments, a rest time buffer must provide at least a 98% reliability factor. For low priority flight segments, the rest time buffer must provide at least a 97% reliability factor. As another example, column  540  of the table  530  identifies allowable reliability factors for connection risk (e.g., the amount of time it takes a pilot to transfer from one aircraft at an airport to a second aircraft at the airport). For example, for high-priority flight segments, the connection buffer must provide at least a 97% reliability factor. For medium priority flight segments, a connection buffer must provide at least a 96% reliability factor. For low priority flight segments, a connection buffer must provide at least a 95% reliability factor. The exemplary reliability factors shown in table  530  are merely examples provided for illustration purposes. An airline may determine reliability factors that suit its strategy. 
     Personnel may have personal limits related to operation priority. For example, continuing the examples above, pilots may be limited to performing one high priority flight segment in a duty period. 
       FIG. 6  illustrates a scenario  600  that is similar to the scenario  400  shown in  FIG. 4 , except that the combinations of flight segments for flight crews (from inbound flight segments to outbound flight segments) are based on a prioritization of the outbound flight segments. Flight segment  608  is scheduled to arrive in Atlanta at 11:50 AM, but the flight segment  608  is historically late by thirty minutes or more 5% of the time. The remaining flight segments  610 ,  612 , and  414  arrive later but are only thirty minutes late 1% or 2% of the time. Thus, even though flight segment  608  is scheduled to arrive first, for scheduling purposes its crew is treated as if they arrive last due to the higher likelihood that flight segment  608  will arrive at least thirty minutes late. Here, outbound flight segment  618  is determined to be a high-priority flight segment. Flight segments  616  and  622  are determined to be medium priority flight segments, and flight segment  624  is determined to be a low priority flight segment. Referring again to  FIG. 4 , where priorities of the flight segments are not known or assigned, the combination of flight segments for the flight crew of inbound flight segment  610  next included the first outbound flight segment  416 . In the scenario  600  shown in  FIG. 6  however, flight segment  618  has been determined to be of higher priority than flight segment  616 . Thus, the combination of flight segments that includes inbound flight segment  610  also includes flight segment  618  (as denoted by dashed arrow  630 ) even though flight segment  618  is scheduled to depart after flight segment  616 . Consequently, the combination of flight segments that includes inbound flight segment  612  also includes outbound flight segment  616  (as denoted by dashed arrow  628 ). As before in the scenario  400  shown in  FIG. 4 , the combination of flight segments that includes inbound flight segment  614  also includes outbound flight segment  622  (as denoted by dashed arrow  632 ), and the combination of flight segments that includes inbound flight segment  608  also includes outbound flight segment  624  (as denoted by dashed arrow  626 ). With the arrangement of crew assignments shown in scenario  600 , the scheduling risk for high-priority flight segment  618  has been decreased relative to the crew assignments shown in scenario  400 . 
     Additional buffers can also be considered when assigning crews to different flight segments. For example, if the crew of flight segment  612  is likely to arrive in Atlanta with significantly more block time available than the crew of flight segment  610 , then the high-priority flight segment  618  may be included in a combination of flight segments that includes flight segment  612  (instead of flight segment  610 ). As another example, if the crew of flight segment  614  is likely to arrive in Atlanta with a longer period of time until the end of their duty period than the crew of flight segment  610 , then the high-priority flight segment  618  may be included in a combination of flight segments that includes flight segment  614  (instead of flight segment  610 ). 
       FIG. 7A  illustrates a process  700  by which flight segments can be assigned to combinations of flight segments in a manner that the highest priority flight segments are assigned to the least risky combination(s). In block  702 , economic priorities for a plurality of flight segments can be determined. As described above with reference to  FIGS. 5A and 5B , the economic priorities for the flight segments can be based on objective criteria, subjective criteria, or a combination of objective and subjective criteria. In block  704 , possible combinations of flight segments of the plurality of flight segments are identified. In block  706 , for the different possible combinations of flight segments, a likelihood that personal limits will be exceeded by the combination of flight segments can be determined. For example, a first combination of flight segments may have a 95% chance of not exceeding the personal limits of a pilot, based on past instances of the flight segments in the combination, and a second combination may have a 99% chance of not exceeding the personal limits. In block  708 , the highest priority flight segment is identified and assigned to the combination of flight segments with the lowest risk of personal limits being exceeded by the flight segments. As described above with reference to  FIG. 5B , in various instances, the highest priority flight segment may be in a group of flight segments that are identified as being highest priority. For example, in  FIG. 5B , a flight segment with an overall rank of 1 to 2.5 is considered to be highest priority. Furthermore, the highest priority flight segments may have different tolerable risk levels than medium priority or low priority flight segments. In such instances, the high-priority flight segments may be assigned to any one of a group of possible combinations of flight segments which have risk levels that satisfy the tolerable risk levels for a high-priority flight segment. In various other instances, flight segments may be ranked in a manner such that there is an identifiable highest priority flight segment amongst the plurality of flight segments. In such an instance, the highest priority flight segments may be assigned to the possible combination of flight segments which has the lowest risk level. 
     After the highest priority flight segment in block  710  has been assigned to a combination of flight segments, the process  700  can proceed to assign the remaining flight segments to combinations of flight segments in rank order based on priority of the flight segment. In block  710 , the process  700  can identify the next highest priority flight segment from among the plurality of flight segments and assign this flight segment to a combination of flight segments that has the lowest risk of personal limits being exceeded by the flight segments. It is possible that the highest priority flight segment and the next-highest priority flight segment could be assigned to the same combination of flight segments or to different combinations of flight segments. In block  712 , the process  700  determines whether all flight segments have been assigned to combinations of flight segments. If so, then in block  714 , the process  700  ends. If additional flight segments have not been assigned to combinations of flight segments in block  712 , then the process  700  returns to block  710  and continues to assign flight segments to combinations of flight segments by selecting the next highest priority flight segment and assigning flight segment to the possible combination of flight segments that is least likely to exceed personal limits. 
     In various instances, after the process  700  ends, the combinations of flight segments can be assigned to itineraries. Then, flight segment crews can be assigned to the itineraries. 
     In various aspects, it is possible that an airline may know the priority of its flight segments but may not have the information to determine the likelihood that a pilot&#39;s personal limits will be exceeded by a particular flight segment (based on the pilot&#39;s flight segments leading up to the particular flight segment). In such instances, pilots could be assigned to the flight segments based on available personal limits. Referring to  FIG. 7B , a process  730  can begin in block  732  by determining the economic priorities for a plurality of flight segments. In block  734 , candidate pilots to perform the plurality of flight segments can be identified. In block  736 , for the candidate pilots remaining, personal limits can be determined (e.g., based on block time, duty time, rest time, or the like). In block  738 , the pilots with likely the most remaining personal limits can be assigned to the highest priority flight segments. In various aspects, pilots could be sorted into ranges of available personal time for flight scheduling purposes for example, if a first pilot has two hours of remaining block time at a second pilot has five hours of remaining block time, then it could be advantageous to reserve the second pilot for longer flight segments (e.g., flight segments of three or four hours in length) and to use the first pilot for shorter flight segments (e.g., flight segments of approximately one hour). After pilots have been assigned to the highest priority flight segment, then in block  740 , pilots (from among the remaining pilots) with the next most remaining personal limits are assigned to the next highest priority flight segment. In block  742 , the process  730  queries whether crews have been assigned to all flight segments. If so, then in block  744  the process  730  ends. Returning to block  742 , if additional flight segments have not been assigned to crews, then the process  730  returns to block  740 . 
     The above-described aspects can be applicable to other groups of operators than pilots. For example, aspects can be used to schedule train operators, flight attendants, harbor pilots, etc. As another example, aspects can be used to schedule surgeons for elective surgical procedures to ensure that surgeons do not become overly tired during a duty period. 
     The descriptions of the various aspects of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the aspects disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described aspects. The terminology used herein was chosen to best explain the principles of the aspects, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the aspects disclosed herein. 
     In the preceding paragraphs, reference is made to aspects presented in this disclosure. However, the scope of the present disclosure is not limited to specific described aspects. Instead, any combination of the preceding features and elements, whether related to different aspects or not, is contemplated to implement and practice contemplated aspects. Furthermore, although aspects disclosed herein may achieve advantages over other possible solutions or over the prior art, whether or not a particular advantage is achieved by a given aspect is not limiting of the scope of the present disclosure. Thus, the preceding aspects, features, and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s). 
     Aspects may take the form of an entirely hardware aspect, an entirely software aspect (including firmware, resident software, micro-code, etc.) or an aspect combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” 
     Aspects may be a system, a method, and/or a computer program product. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention. 
     The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
     Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device. 
     Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some aspects, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention. 
     Aspects are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to aspects of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
     These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various aspects of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     Aspects may be provided to end users through a cloud computing infrastructure. Cloud computing generally refers to the provision of scalable computing resources as a service over a network. More formally, cloud computing may be defined as a computing capability that provides an abstraction between the computing resource and its underlying technical architecture (e.g., servers, storage, networks), enabling convenient, on-demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction. Thus, cloud computing allows a user to access virtual computing resources (e.g., storage, data, applications, and even complete virtualized computing systems) in “the cloud,” without regard for the underlying physical systems (or locations of those systems) used to provide the computing resources. 
     Typically, cloud computing resources are provided to a user on a pay-per-use basis, where users are charged only for the computing resources actually used (e.g. an amount of storage space consumed by a user or a number of virtualized systems instantiated by the user). A user can access any of the resources that reside in the cloud at any time, and from anywhere across the Internet. In context of the present invention, a user may access applications (e.g., a crew scheduling application) or related data available in the cloud. For example, the crew scheduling application could execute on a computing system in the cloud and analyze historical flight segment data to identify time variances. In such a case, the analysis of historical data could operate on historical flight segment information stored at a storage location in the cloud. A resulting crew schedule could also be stored at a storage location in the cloud. Doing so allows a user to access this information from any computing system attached to a network connected to the cloud (e.g., the Internet). 
     While the foregoing is directed to aspects, other and further aspects may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.