The Cheap Flight That's Actually Worth Booking

Most price alerts are built to find one thing: a low number. So that's what they send you - a fare that's genuinely cheaper than usual, sitting on a routing with a 10-hour layover somewhere you've never heard of, or a departure so early it costs you a night's sleep to catch it. Technically a good price. Not actually a good deal, because you were never going to book it.

Why "cheap" alone is a bad filter

A price-only alert is optimising for exactly one variable, and treating everything else as invisible. A fare that's £80 cheaper but adds a connection you'd never actually sit through isn't a better deal once you account for the day you lose or the risk of missing it - it's just a smaller number on a flight that was never really on the table. "Cheap" and "worth booking" get treated as the same claim by most tools. They aren't.

Define "acceptable" once, not every time you check

The tiring part of watching a route isn't finding fares - it's re-filtering the same junk out of the results every single time you look. Skipping past the ones with layovers you'd never accept. The ones landing well past midnight. The ones on an airline you've sworn off after a bad experience. Doing that by eye, over and over, is the actual manual labour of "finding a cheap flight" - the price-checking part is the easy bit.

The fix isn't accepting worse flights. It's deciding what "acceptable" means to you once, up front, and having every future result already filtered against that bar before you ever see it - instead of re-deciding the same thing on repeat.

What that actually looks like

In practice, that's a short list of real settings, not a vague preference: a maximum layover duration, so a "1 stop" search stops meaning "any stop, however long." Direct-only if that's simply non-negotiable. Departure-time windows for both legs, so a flight that's cheap because it leaves at 4am never counts as a match. Airlines you'd rather include or rule out entirely. Set once, each of those keeps applying to every future scan - not just the search you happened to run today.

A genuinely good deal is the intersection of affordable and acceptable, not just the lowest number that technically exists on the route. Catching that intersection reliably - on the next search and the one after that, not only this one - is what an alert built around your own criteria is actually for, rather than one built around price alone.

For more on picking the number worth waiting for in the first place, see What's a Good Price for a Flight?