Fewer 3-hour delays, higher cancellation rates – GAO report


The "3-hour rule" regarding flight delays was supposed to make things better for passengers by preventing them from being stuck on airplanes on the ground rather than actually flying. And the statistics year-over-year since the rule was implemented are pretty clear: the number of 3 hour delays dropped from 693 to 20 the year before and year after the rule was implemented. Great news, right?

Maybe not. According to a recent report from the GAO the reduced delays come with a side-effect of making flight cancellations much more likely:

GAO analysis suggests the rule is also correlated with a greater likelihood of flight cancellations. Such cancellations can lead to long overall passenger travel times. Airlines and other aviation stakeholders maintain that the tarmac delay rule has changed airline decision-making in ways that could make cancellations more likely.

The report is 111 pages of tables, statistics and generally dry reading. But there are some telling numbers that come out of it. The GAO performed two different regression analyses against the data covering 70 airports around the USA and Puerto Rico. Data was reviewed for both flights canceled before they left the gate and after they left the gate and began to taxi. Unsurprisingly, more flights are canceled at the gate than once they’ve pushed back. But the data from 2010 – after the new rule went into effect – suggests that cancelations are notably more common in both scenarios.

The number of flights cancelled in each year was incredibly small once the plane actually left the gate. Only 992 flights of the 1,846,288 scheduled flights that pushed back from the gate ended up not flying. But that number was 24% higher weighted for the total number of scheduled flights. And the chances of a cancelation are dramatically higher as the time on the tarmac grows. A plane that has been taxiing for more than 60 minutes was 88% more likely not to fly. Over 120 minutes that number was 216%. For flights that never left the gate the odds of a cancellation were also higher, to the tune of 13% year-over-year with 2010 having just over 1% of flights canceled at the gate.

Those are the unadjusted, raw data numbers from the DoT and FlightStats reports. The GAO also performed regression analysis to determine what other factors – weather, ATC, flight distance, time of day and others – might affect the cancelation rates to see if the rule is better or worse than other effects. The numbers do not appear all that promising for passengers. For the Tarmac-Cancellation Model (post push-back) the GAO has the following to say:

In all hour categories of tarmac time, the odds of cancellation were greater in 2010 than in 2009 because all of the odds ratios exceed 1. Moreover, the differential in the odds ratio of cancellations across the 2 years increased with the time a flight was on the tarmac. For flights that were on the tarmac for less than an hour, the odds of a cancellation were about one-third higher in 2010 than in 2009. … For flights with 61 to 120 minutes of tarmac delay, the odds ratio rose to 2.14, indicating that the odds of a cancellation more than doubled in 2010 compared with 2009, and for flights with 121 to 180 minutes of tarmac delay, the odds of cancellation more than tripled in that same time period. …[T]he inclusion of key variables to control for other factors did not have much effect on our findings related to the tarmac rule.

For the Gate-Cancellation Model the numbers are actually even more dramatic:

One significant finding is that the odds ratio for the rule change is substantially greater, when adjusted, than indicated by the simple unadjusted odds ratio shown in table 16. The model results indicate that the odds of gate cancellations rose by 24 percent after the rule went into effect, whereas the simple result indicated only a 13 percent increase in those odds.

Yes, fewer folks are sitting on the airplanes, but fewer are also actually getting where they are going. That’s not necessarily a good thing.

The report recommendations are pretty toothless, suggesting that the DoT collect more data than they do today and better analyze it for comprehensive impact against passengers. Not likely that will have much impact in the long run.

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Seth Miller

I'm Seth, also known as the Wandering Aramean. I was bit by the travel bug 30 years ago and there's no sign of a cure. I fly ~200,000 miles annually; these are my stories. You can connect with me on Twitter, Facebook, LinkedIn and .

6 Comments

  1. Not a problem. I would much much much rather go sit in the skyclub or be at a nice hotel than stuck forever on a non-flying tin can! I can wait for the next bus.

    1. I’d rather be in a lounge or a hotel, too. But that’s not really the net outcome of these cancellations. With load factors hovering north of 80% these days getting accommodated isn’t a 2-3 hour delay for most folks; it can be 2-3 days in many cases. And if there are several flights canceled finding those hotel rooms will be difficult and likely rather expensive. Not great options at all.

  2. My SW flight (TUL-DAL) was cancelled yesterday just 20 min before takeoff as well as my eventual seat mate from MCO (we both got rerouted to HOU). What a long day. Added 4 hrs. And no vouchers though I am petitioning SW.

  3. It’s pretty obvious that, if the Government says to airlines that it will fine them large sums of money unless they cancel flights, the airlines will choose to cancel flights.

    Badly thought through laws create problems – always.

  4. The airline industry complains about this but has yet to propose an alternative solution that avoids the problem: airlines allowed people to get stuck on planes and treat them with indifference. They had over 10 years to come up with any self-regulated solution and failed to take the problem seriously let alone take meaningful action to address it.

    The government acted and solved the problem. You may not like the rule or any side effects, even though the side-effect is overblown by almost all travel pundits and bloggers, but the fundamental problem was solved.

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