Airfare-Prediction Apps Can’t Handle a Summer Like This One

The casual air traveler has never had so much information at his fingertips. He sits before a battleship-worthy console of maps, prices, dates, and times; orders up grids that plot one variable against another. He is monitoring the situation. He is in conversation with his wallet, but also with his future self: Will he want to take the red-eye and leave his bags at the hotel all day? Will he want to leave the house at 4 a.m.? What’s so great about Iceland, anyway?This stupendous array of choices, once reserved for professional travel agents, is emblematic of our optimized-shopping era. Consumers don’t just price-shop; they scrutinize rates of change, guided by algorithms that purport to know where prices are headed. With airfares at historic highs, the sites that advise travelers whether to buy now or wait have never felt more necessary. Unfortunately, they have rarely felt less helpful.Sites such as Hopper, Kayak, and Google Flights are trained on price histories. “They use data from the past to inform models in the present that make predictions for the future. Their level of confidence and predictive accuracy drops—whether they disclose that or not—precipitously when there are exogenous shocks,” Oren Etzioni, a computer scientist who built and sold the pioneering airfare-prediction site Farecast to Microsoft in the 2000s, told me. The sites’ powers are limited in chaotic times, and chaotic this summer is.Fare changes are a cat-and-mouse game in which airlines try to fill empty seats and capitalize on last-minute travel needs—countervailing tendencies that can lead to lower or higher prices, respectively. In the main, as most air travelers have probably experienced, the overwhelming trend is for tickets to get more expensive as the date of a flight approaches. But algorithms have been able to deduce currents within that rising tide. Generally speaking, these sites offer decently reliable predictions. AirHint claims that its recommendations are correct 80 percent of