How the Touchdown Quality Index works, and what it cannot tell you

The Touchdown Quality Index (TQI) is this site's measure of how landings were rated. This page explains how it is built and what it leaves out; the full method is on the methodology page.^[1]

One rating

A rating is 0.5 to 5 stars in half-star steps, where 5 is the smoothest. The TQI for one rating is the star rating divided by 5 and multiplied by 100, so a 4-star landing is a TQI of 80. Nothing else is added.^[1]

• Smooth: 4 stars and above.^[1]
• Firm: 2.5 to 3.5 stars.^[1]
• Rough: below 2.5 stars.^[1]

When a score appears

A carrier, airport, route or aircraft gets a score once it has 5 ratings. Below that, its page shows the count and the score reads n/a. A score from fewer than 30 ratings is marked provisional.^[1]

Published scores are pulled toward the average across all ratings, so a short run of ratings cannot outrank a large sample: score = (n x mean + 5 x global mean) / (n + 5). Five ratings averaging 90, against a global mean of 70, give a score of 80.^[1]

What it cannot tell you

The index records what people felt. It does not measure touchdown speed or g-load, and public ADS-B tracking is too coarse to show how firm a touchdown was. Seat position, aircraft type, wind and expectations all affect what people report, and the index does not correct for them.^[1]

Nothing confirms that the person rating was on the flight. 'Signed in' means a Google account was used. Imported ratings are scores for past flights from the last 12 months, given from memory.^[1]