Last night in the 8:00pm EDT U.S. domestic airfare distribution, United Airlines raised airline ticket prices between $4 and $50 roundtrip for the bulk of its route system. United spokesperson Robin Urbanski told FareCompare that the hikes can be blamed squarely on the airline’s highest expense: fuel. Said Urbanski, “Fuel costs continue to be record-breaking.” This is not only the 4th attempted weekly increase in a row — it’s also the 8th attempted increase in this year alone (and 5 of the previous 7 increases have been successful). And this increase broke the pattern; in other words, it wasn’t just another “let’s-raise-the-fares-by-a-measly-10-bucks”. Not this time! Keep reading for more…

No, instead of a somewhat easy to swallow $10 increase, some of these price hikes are $50 round trip and they affect 2,500 leisure city-pairs and 3,800 business city-pairs!

This United increase is mostly based on mileage distance of the route (with several exceptions) and is laddered as follows (leisure, 14 days advance purchase or more, business, less than 14 days advance purchase):

• $4 roundtrip increase - 300 leisure city pairs, 700 business city pairs
• $8 roundtrip increase - 1,500 leisure city pairs, 3,800 business city pairs
• $10, $11, $12 roundtrip increase - 3,900 leisure city pairs, 5,800 business city pairs
• $20 roundtrip increase - 200 leisure city pairs, 180 business city pairs
• $30 roundtrip increase - 5,000 leisure city pairs, 6,200 business city pairs
• $50, $52 roundtrip increase - 2,500 leisure city pairs, 3,800 business city pairs

The total city pairs with an increase are approximately 20,000.

And here’s something really interesting: a quick check Denver (a United Airlines hub) shows this laddered increase on dozens of city pairs, even on overlapping Southwest Airline markets.

Legacy airline matching may take some time as they try to absorb the intricacies of this complex airfare hike.

We will be following this and updating as soon as we learn more.