FAQ - FREQUENTLY ASKED QUESTIONS
SCHEDULE CHANGES REPORT
2) DO THE SCHEDULES SHOWN HERE CHANGE AFTER YOU POST?
4) WHAT ABOUT CARRIERS THAT DON'T PUBLISH A SCHEDULE 9 MONTHS IN ADVANCE?
5) HOW ARE THE DAILY DEPARTURES CALCULATED?
6) WHAT ARE THE FRACTIONAL FLIGHTS??
2) DO THE SCHEDULES SHOWN HERE CHANGE AFTER YOU POST?
To improve is to change; to be perfect is to change often---Winston Churchill. This is data the carriers filed at the point in time it was captured. It's probably changed since then.
3) HOW DO I READ IT?
ABE-ZIH DEC 4>5[4] JAN 4>5[4]
ABE= Departure IATA code (Allentown in this case)
ZIH= Arrival IATA code (Ixtapa in this case)
DEC = Month (December in this case)
4 = Average Departures/Day over the month for sale as of last week
5 = Average Departures/Day over the month for sale as of this week
[4] = In brackets is the number of Average Departures/Day over the month that were scheduled one year earlier. So, it means that the listed airline changed the frequency between the two airports to add from 4 to 5 roundtrips in December and January. It also means that there were 4 roundtrips the prior year in each month. No other months were changed.
Process repeats for subsequent months with changes. I average two directions ([inbound + outbound] / 2).
4) WHAT ABOUT CARRIERS THAT DON'T PUBLISH A SCHEDULE 9 MONTHS IN ADVANCE?
Sometimes airlines do not load their schedules for the entire 330 day standard sales window. Southwest and many LCCs load their schedules for as little as 5 months into the future. When these flight are extended into a new sales month, it becomes a "schedule change". When a flight is loaded from 0 departures to X departures, where X was the same the prior year, the record will not be shown. For example, if Delta loaded ATL-EGE MAR 0>1(1), it would not be shown because this additional flight does not represent a real year-over-year addition. Similarly, if B6 extended their schedule a record like this ATL-BOS JUL 0>4(4) would not be shown. It will be shown if the flight frequency changed from the prior year. So B6 ATL-BOS JUL 0>3(4) would be shown. If a partial month was loaded in a core schedule that became a full schedule month, those changes may be shown under this logic. For example, WN BNA-SEA 0.3>2(2). Because only a fraction of the month was previously loaded for sale, these changes will not be filtered out.
5) HOW ARE THE DAILY DEPARTURES CALCULATED?
This report uses total operations for the month listed, divided over the days in the month. The following criteria are used to show a change: 1) The change must be at least 6 roundtrips per month with no exceptions, 2) changes of at least 6/week are always shown, 3) routes that are added or dropped are shown subject to the change minimum, and 4) in all other cases routes must change by 20% to be shown. For example, if a route changed from 21/week to 18/week it would not be shown because the change is -14.3%. This is done to filter minor changes that occur in large numbers.
6) WHAT ARE THE FRACTIONAL FLIGHTS?
Flights that do not operate every day of the month create fractional service. If the route has more than 2 daily flights, departures are rounded, but in cases of less than 2 departures per day a fraction is shown. For example, if a flight operates 4 times in April it will show 4/30=0.133=0.1. Also , a flight that only operates once per week may vary between 0.1 and 0.2 because a weekday may repeat either 4 or 5 times depending on the month.
7) THOSE FLIGHTS AREN'T DELTA, THEY ARE SKYWEST?
This report only shows the marketing code. It is too complicated to show all the operators.
8) THE FREQUENCIES MAY HAVE CHANGED AS YOU SHOW, BUT THE SEATS DIDNT CHANGE BECAUSE OF EQUIPMENT SWAPS?
Seats are not shown. That is a natural weakness of a frequency based report, but it provides something to discuss.
9) THIS LOOKS LIKE AN ERROR?
The carriers file the schedules. They do make mistakes. Most of the mistakes I have seen are either related to code shares not being marked as "duplicates" or carriers filing flights with invalid data such as equipment codes that are not standard or overlapping schedule periods that see the same flight number in two places at once. These cause flights to not appear. We also see situations where the data is capctured in the middle of an airline updating its schedule. For example, at 1013pm AA deletes its schedule to/from ORD for April to June and begins adding flights back in at a rate of a dozen every second, requiring several minutes to complete the update. If the data is captures at 1016pm some flights may not have been reloaded for sale yet.
10) ONGOING ERRORS?
When these types of recurring errors occur it is 99% of the time prior to my receiving the data. If you can identify a pattern (It’s only when its a Skywest operation as AA with flights on CR7), I can report it.
11) CURRENT MONTH CHANGES?
I don’t report any data for the current month and never have because the number of departures decreases based upon the number of days left in the current month which creates many problems. So when an airline cancels flights less than 31 days from the start of the flight it may never been shown and when the prior year numbers are displayed, they will also reflect what was for sale the prior year the month before the flights were supposed to operate.
12) CHARTERS?
Charters and non-scheduled flights may show up if the airline puts them in their filed schedule. Just because a flight is listed here doesn't mean you can buy tickets on it. In order for a flight to be "sellable" there must be a schedule filed, there must be prices filed, and there must be inventory marked open in the airline's revenue management system. Charter that are published in their public schedule typically do not have open inventory making them invisible to the public.