The Alaska Pilots Podcast

TA 3: PBS and Trip Construction

September 23, 2022

This tentative agreement includes a preferential bidding system (PBS) as the delivery process for monthly schedules. Hear about ALPA’s enhanced control over trip construction and how PBS will work.

Many terms may be unfamiliar. Some may find the glossary below helpful while listening to this episode.

Find more information at

PBS Hotline: (833) ALA-PBS1 or (833) 250-7271

Preferential Bidding System (PBS) Glossary


Average Line Value (ALV)

The average Credit value of all lines in a Base Position.  ALV will include all known Credit in that Base Position.


Correct Line:

The initial line the Pilot should have been awarded had a PBS Misaward not occurred.


Credit Window

Credit range within which a line may be awarded.


Denial Mode

A process in PBS that:

  • is performed after PBS is unable to award a Pilot a line consistent with his or her bid preferences, seniority, known absences, the FARs, and the CBA, and within the Minimum Credit Window,
  • is utilized after shuffle and prior to Secondary Line Generation (SLG), and ignores, one at a time, a Pilot's preference(s) to avoid flying a specified trip or a trip with specified criteria (e.g., number of duty periods in a trip, departure time of trip, number of flight segments per duty period) or the Pilot’s preference to avoid flying on a specified Calendar Day, in an effort to award a line within his or her Minimum Credit Window.


Fill to Threshold

A tool in PBS that is utilized prior to Denial Mode, and continues to award trips to each Pilot's line, if possible, until such line is at or above the threshold.


Force Priority Stack Date on SLG

A tool in PBS that ensures a Pilot who is awarded a line during the SLG process is awarded a trip that is scheduled to operate on the specified priority stack date.


Max Followed By Time

The maximum time between trips that are awarded via the "Followed By" bid statement.


Max Iteration

A parameter in PBS that limits the number of trips PBS considers when attempting to construct a line.


Max Passes

A parameter in PBS that limits the number of attempts by PBS to award lines to all Pilots in a Base Position.


Max Reserves

A parameter in PBS that limits the number of Pilots permitted to be awarded a Reserve Schedule in a Base Position.


Maximum Stack Height

A parameter in PBS that limits a stack after all Pilots in the Base Position are awarded a line.


Priority Stack Date

A designated date that is unstacked before PBS unstacks any other date. Priority stack date is limited to days which receive Holiday Pay.


Reduced Lower Limit (RLL)

A line that is awarded below the minimum Credit value for the Month when the Pilot could not legally be awarded a line within the Credit Window.


Secondary Line Generation (SLG)

The final PBS process, used after Shuffle and Denial Mode, that ignores a Pilot's bid preferences in an attempt to construct a line for the Pilot.



A tool in PBS that:

  • is utilized after PBS is unable to award a Pilot a line within his or her line credit window which complies with his higher priority bid preference(s)
  • removes a trip(s) which had been awarded in accordance with such bid preference(s) and searches for combinations of trip(s) which comply with his or her lower priority bid preference(s), and
  • is utilized prior to Denial Mode.



The number of duty periods that remain in Open Flying Time on a given Calendar Day at the end of a bid run.



The target Credit value for each line in each Base Position in a Bid Period.


Trailing Line Value (TLV)

The twelve (12) Bid Period rolling average of the ALV for a Base Position.



A tool in PBS that assigns trips to Pilots in such a way as to prevent a stack that is greater than the Maximum Stack Height.


Vacation Any

A function applied during the PBS award process in which vacation days may be moved as needed so as to avoid conflicts with preferred trips. Vacation Any does not change the number of vacation days or the Credit of the awarded schedule.


Virtual Credit

A credit value applied to an activity or absence only during schedule construction in PBS.  Virtual Credit has no value once the schedule is awarded.

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