If you’re reading this, chances are you are an instrument-rated pilot, or at least considering becoming one. Under instrument flight rules, if the weather, plus or minus an hour of your ETA, is expected to be worse than a 2,000 feet ceiling and visibility of less than 3 miles, you need to file an alternate (this is known as the 1-2-3 rule).
The airlines use the same criteria, though there are several exemptions that the FAA will grant that allow for different alternate determination rules and alternate selection rules. It depends on the airline, its equipment, safety record, et cetera. But even then, everything starts with the 1-2-3 rule. And often the alternate that is given is not always the best choice.
Nobody ever wants to divert. Diversions are inconvenient, and whether you are a general aviation guy in a Cessna 172 or an airline, diversions also cost money. When the fuel is Jet A at a relatively low altitude, the costs add up quickly. Further, carrying any extra fuel also costs money. Therefore, it stands to reason that when an alternate is listed, it should be as close to the destination as possible, right? Not necessarily.
Back in my regional days, I was based in Cincinnati (CVG), and when the weather was low enough to require an alternate, the company would frequently use the nearby Lunken airport (LUK). This was a “paper” alternate, in that it satisfied all of the regulatory requirements.
However, there was never any intention that we were going to land at LUK. The point of listing it was to minimize the cost of carrying alternate fuel for a more realistic station (in our case, typically Dayton, Indianapolis, Louisville or Lexington). We didn’t serve LUK, and the airport had no TSA presence, so deplaning passengers would have created a nightmare. We also didn’t have a fuel contract there, so getting fuel would have been expensive.
I’ve seen this issue in more than one metro area. Airlines going to New York will use another airport in the New York area—Islip, White Plains, Stewart, to say nothing of the more common JFK/LGA/EWR trio—that they don’t serve just to minimize costs. And most of the time, this works. Dispatchers don’t typically use one of these paper alternates unless they a) have to, and b) are confident that the weather won’t go much lower than the 2,000 and 3 that requires an alternate in the first place. But still…things can happen.
When you see one of these scenarios develop, you have to decide whether to go along with the eternal optimism of the dispatchers that things will work out as planned, or call them and discuss a more realistic option. Since the captain and dispatcher both have to sign off on the flight, you do have some leverage. Or, you can take your chances and land at a small podunk airport and watch the show as everything unravels—for which you will be blamed in some way, shape, or form.