I found the following information about northern Michigan May passenger loads interesting. As has been mentioned in another thread MBL saw 431% growth over the previous year with the introduction of F9 service. Where did the 2500 additional passengers come from?

A reasonable expectation would be that Manistee's gain would come at the expense of the next nearest airport TVC. Especially as TVC has high fares with no LCC present. But if you look at the data you see something very different. From January through April TVC traffic was essentially flat(+0.3%) as compared to the previous year. However in May TVC saw an increase of 11.9% (21523 to 24080) vs the previous year. You can also see the same thing at the other northwest Michigan airport PLN; flat Jan-April (-2.6%) then 14.7% growth in May (2837 to 3254).

Why is there suddenly growth in passenger numbers for all three of these northwest Michigan airports beginning in May? I attribute it to the "Frontier Effect" (no reason WN should have a monopoly on the term). The entrance of an LCC into a region has likely lowered fares at the nearby airports stimulating demand throughout the region.

Mike Boyd gave a presentation last month in Traverse City were he claimed that the region was suffering 60% leakage to downstate airports in GRR, FNT, LAN and DTW. Is it possible that Frontier has positively impacted all airports in the region?

There is a lot of conjecture here based on one month's worth of data, but I can't think of any other explanation for the simultaneous growth at all three airports.