TSA screening counts arrive about three months ahead of the official passenger figures and move with them at a steady ratio. The nowcast applies that ratio to the quarter still being counted and is not a demand model.
What this shows: The chart covers 2019 Q1 to 2025 Q4. It plots BTS T-100 passengers, TSA checkpoint throughput, TSA nowcast and BTS partial (incomplete T-100) on a vertical axis of Passengers (millions, quarterly). Latest values: BTS T-100 passengers 288.9 (2025 Q3); TSA checkpoint throughput 228.3 (2025 Q4). Projected to 2025 Q4: TSA nowcast 279.3. Data run through 2025 Q3; the chart extends to 2025 Q4.
Conditions and method
Status: descriptive (the compared series are near-identical tallies by construction, so a tight fit is expected rather than evidence of skill).
This is a ratio bridge for nowcasting partial or missing T-100 quarters. BTS T-100 passengers are nearly the same count as TSA checkpoint throughput (BTS is about 1.21 times TSA), so the small error (1.17% mean absolute percentage error) is near-mechanical. The regression’s marginal value over a naive per-quarter BTS-to-TSA ratio, whose error is 2.40%, is 1.23 percentage points. The close fit is not evidence of forecast skill.