Airlines don't sell you travel, they sell time. Their entire business is built around schedules. Everything is about time. And since time is money, let's take a look at ground time. As a backdrop, please keep this table in mind, as it's crucial. This table summarizes operating costs from DOT's Form 41. The data is filed by airlines as part of their data sharing with the DOT—our metric looks at operating expenses divided by airborne time. [caption id="attachment_92235" align="aligncenter" width="562"] US DOT; AirInsight[/caption] Airlines must pay for their infrastructure, whether it is in the air or on the ground. Because flying generates revenue, aircraft on the ground means costs with no revenue. Airlines and their suppliers will tell you that AOG (aircraft on ground) is the worst. But don't take our word for it. Several years ago, Robert Isom was a senior leader at US Airways. He gave a presentation on the importance of an airline being on time. It is probably one of the better briefings on this subject. Meet TGT So, how much ground time does an airline experience? Using ADS-B data for a random period in 2024, we were able to develop this series of charts. We are focusing on the big four US airlines only. The abbreviation we use for total ground time is TGT, measured in minutes. We are comfortable that the TGT shown is a reasonable average metric. ADS-B data provides a convenient new way to visualize differences in TGT across airlines and airports. We started our exploration with a few simple questions: How do total ground times differ across the four US majors? Where does each airline have its highest TGT? What impact might differences have on cost structures? In this initial piece, we'll share what we see and why we think it should spark a conversation across the industry. [caption id="attachment_92238" align="aligncenter" width="357"] ADS-B; AirInsight[/caption] ADS-B is an excellent, objective source for tracking flight operations. Airline managers and pilots invariably argue with the DOT data. ADS-B is something much more challenging to dispute, as no one in or near an airplane has control over it. Would it be too much to argue that this source is the future of flight ops tracking? Distilling Ground Times This wide variance is surprising. Examining the cost table, you can immediately gauge the potential impact. According to the DOT's on-time dataset, the taxi times are shown below. These times apply only to domestic flights. But the data provides the guidance. [caption id="attachment_92241" align="aligncenter" width="640"] DOT; AirInsight[/caption] Now, let's look at the 2024 US airline domestic flight profiles by time, focusing on the last column. Taxi times are on the ground. We need to factor this into the TGT to get a ground time profile. Taxi time is a significant proportion of the total elapsed time. [caption id="attachment_92242" align="aligncenter" width="716"] DOT; AirInsight[/caption] Comparing the Big Four Now, as we combine the data points, we can estimate the time at the gate. Gate time is the difference between TGT and taxi times. The differences between the big four airlines are fascinating. This table alone is worth a lengthy discussion among industry followers. [caption id="attachment_92244" align="aligncenter" width="330"] AirInsight[/caption] Preliminary Implications Here are four charts showing the big four by number of flights over the four weeks and the average TGT. The analysis is preliminary as we become more familiar with the data and refine it further. Here are some preliminary implications. TGT is high at hubs. That may not be a bad thing, considering the connection to banks—notice also that Hawaiian airports feature prominently in terms of TGT. The dashed horizontal line is the average. [caption id="attachment_92249" align="aligncenter" width="640"] American Airlines TGT[/caption] Hubs and high-flight volume airports feature prominently. Examining the differences in average TGT compared to the hubs reveals a likely cost implication. [caption id="attachment_92250" align="aligncenter" width="640"] Delta Air Lines TGT[/caption] Atlanta is in a world of its own. This must be costing Delta some money, as ATL has a 23.8-minute longer than average TGT. If $84/minute is a guide, then the costs are enormous. [caption id="attachment_92251" align="aligncenter" width="640"] Southwest Airlines TGT[/caption] An airline with no hubs, but many connecting airports, presents an unusual picture. And it's not pretty because most of these connecting airports generate high TGT. [caption id="attachment_92252" align="aligncenter" width="640"] United Airlines TGT[/caption] Consistent with what we see from its peers. Hubs are a problem, and the potential cost is significant. One might consider that hub control offsets these costs. That idea requires more analysis. Summary ADS-B appears to offer a convenient new way of viewing airline flight operations. As we access more data, we will publish more analyses.