Write the comparison question first
“Which airport has more delay?” is incomplete until you choose a period and measure. A count of disrupted flights, a share of eligible flights and a sum of delay minutes describe different things. The BTS on-time performance overview is a starting point for finding the appropriate collection. Record the dataset's coverage and reporting period before comparing two charts. A large airport can have more delayed flights without having a larger delayed share.
Keep event definitions visible
The BTS technical directive separates scheduled and actual times, gate events and wheels-off or wheels-on events. Choose the field that answers your question, and read the dataset's treatment of cancellations and diversions. An unavailable arrival value is not a zero-minute delay. If you exclude records, explain that decision beside the result so another reader knows whether your comparison describes completed flights or a wider set of scheduled services.
Do not add unlike percentages
A share of delay minutes and a share of flights have different denominators. Even if both charts use percent signs, adding their values does not create a meaningful total. For every number in your notes, write the numerator, denominator, period and filters. If you compare airports, apply the same arrival or departure definition to both. If you compare airlines, verify whether the table groups a marketing network or an operating carrier rather than assuming a brand name always represents the same reporting unit.
Read cause categories as categories
The BTS explanation of reported causes describes broad groups, not a detailed incident narrative for each passenger. Use that reference to interpret the labels instead of treating every category as a single physical cause. A monthly chart is also not a prediction that your next service will be delayed by the same amount. Avoid ranking small samples with precise-looking percentages unless you show the underlying number of eligible flights and the limits of the comparison.
Separate research from today's map
Save the source link, download date, table or query, filters and any transformations alongside a historical result. This makes the comparison repeatable when a dataset is revised. PocketWorld's aircraft explorer shows available observations, not the BTS reporting population or a historical performance dashboard. Counting its visible markers cannot reproduce an airline's on-time rate. Use the map to understand geography and aircraft reports, and the official dataset to answer a statistical question. This guide intentionally publishes no current airline ranking or invented punctuality score.
Data sources
Official references are linked beside the explanations above. This educational guide does not provide current flight status, navigation, dispatch or safety advice.