BenA

I received another one of those Delta marketing e-mails today with a bunch of statistics, and one of them in particular caught my eye:

"Diamond Medallion members will fly enough miles during summer for 85,285 trips around the world!"

I wanted to try to use this to get a more up-to-date estimate of the number of Diamond Medallions; in particular, it would be a useful comparison to future years so we can get a sense of how much the qualification changes affect the overall population.

Let's start by converting this statistic into actual miles. The earth's circumference isn't consistent - it isn't a perfect sphere - but this estimation is going to be so inaccurate that doesn't matter in the slightest. Let's use 24,880 as the Earth's circumference, resulting in 2,121,890,800 miles flown by Diamonds during the summer.

Next, we need to convert this to an annual amount. Delta doesn't define "Summer" in the e-mail, but I'm going to assume it's the months of June, July and August - roughly Memorial Day to Labor Day. We can figure out exactly what proportion of passenger miles is flown during the summer - in 2017, across all scheduled passenger airlines touching the US both domestic and international, it was 28.44% according to the Bureau of Transportation Statistics. Let's assume Delta roughly follows that pattern (probably a decent assumption) and that Diamonds fly consistently during the summer (probably a less good assumption, because proportionally more travel will be by non-elites in the summer - so this probably inflates our estimates a little. But lacking better data...). That means that, annually, Diamonds fly 7,460,938,115 miles.

Now we need to estimate the average amount that a Diamond flies to qualify. This is where the estimate goes off into the weeds a little. For one, we don't know if DL's statistic is actual flown miles or MQM credited including bonuses, and if it is Delta only flights or if it includes partners. I'm going to assume it's based on credited MQM, because that would be the easiest statistic for them to pull ("how many MQM did we hand out to all DMs over the summer?"). We also don't know how many MQM on average Diamonds accrue to qualify: there are likely a bunch of 125,000 mile qualifiers relying on CC bonuses and a few 300k+ outliers, and the exact distribution is proprietary.

So let's bracket the results, using three guesstimates at how many miles is average for a DM qualification: my guesstimate is somewhere around 140k, and we'll also run the numbers with 125k and 175k.

125k: 59,687 DMs
140k: 53,292 DMs
175k: 42,633 DMs

So, if these numbers play out, it's likely there are somewhere between 50k-60k DMs, with the real figure probably in the upper level of that range once you factor in comped memberships from corporate contracts, Delta Private Jets, and the like.

In the charter year of the program back in 2010, 32,000 DMs was a widely reported statistic. In 2013, I find a few references claiming 40k. And in 2015, I found a claim of 50-60k. So this number isn't too far out of line: it's pretty reasonable to imagine stable or slightly growing numbers of Diamond members over the last few years, as the revenue based qualification requirements have kicked in and made it more difficult to qualify.

These numbers are useless for basically everything, but it was fun doing the estimation!