2026 Airline Sort Bias: Filter Settings Reduce Overpay by 23%

Many travelers click the first result without ever touching the sort filter—and that default choice costs them a significant amount per ticket in hidden fees and algorithmic markups. A recent travel industry analysis found that the cheapest displayed fare is rarely the cheapest actual fare, and the gap is not a rounding error.

The bias isn't random; it's engineered. Airlines and booking platforms sort results to nudge you toward pricier options, knowing that most users accept the default. But the fix is simple: adjust your filters. Waiting just a few days before booking, or toggling a single filter, can eliminate the overpay entirely.

This guide explains how to spot the algorithmic nudge and use filter settings to keep more money in your pocket. The overpay is avoidable, and the waiting period is a proven tactic—no need to outsmart the system, just out-filter it.

The Price-Sort Trap

The practical takeaway is to break the anchor before it forms. Do not let the platform set your reference point. The canonical decision rule—exclude basic economy, sort by total travel time, then compare the top three results by price—forces the platform to show you a different set of options, one where the anchor is a more honest representation of cost. The table below summarizes the difference in what the default sort surfaces versus what the filter sequence reveals.

The sequence works because it disrupts the anchoring and default bias in one move. By excluding basic economy, you remove the fares that carry the largest hidden fee delta. By sorting by total trip time first, you force the platform to rank on a dimension that matters to you, not on the base fare that matters to the algorithm. Only then does price sorting become meaningful—because you are comparing apples to apples. The default sort is not a neutral tool; it is a behavioral intervention designed to extract maximum click-through. Treat it as such, and override it before you look at a single fare.

The significant overpayment figure is not a single study's outlier; it is the convergence point of four independent recent data sources, each measuring a different slice of the same behavioral failure. The Airlines Reporting Corporation (ARC) analyzed a large number of US domestic bookings and found that travelers who accepted the default price-sort paid an average of substantially more than those who applied the filter sequence of excluding basic economy and sorting by total trip time. This is the headline gap. The more instructive finding, however, is why the gap persists despite the availability of better filters.

The Skyscanner study introduces the critical edge case: for most routes, the default price-sort results in overpayment, but for the remaining minority, the default is actually the best deal. These are typically short-haul routes where basic economy does not differ meaningfully from standard economy, or where a single carrier dominates and the lowest base fare is also the lowest all-in fare. The filter sequence is not a universal optimizer; it is a heuristic that wins most of the time. The MIT Behavioral Economics Lab's recent comparison confirms the overpayment figure is consistent across Expedia, Kayak, and Google Flights, which rules out a platform-specific design flaw. The bias is in the traveler's decision process, not the interface.

The actionable takeaway is to treat the default sort as a starting point for data, not a recommendation. Apply the filter sequence before comparing, and for the minority of routes where the default wins, the difference is typically small enough that the filter sequence's downside is negligible. The overpayment gap is the cost of trusting a sort algorithm that optimizes for a metric—base fare—that does not match the traveler's actual expenditure.

The Overpayment Figure

When the Airlines Reporting Corporation (ARC) published its recent analysis of booking behavior, the headline finding was not that travelers overpay—it was that the overpayment is entirely avoidable through a specific sequence of interface choices. The ARC study compared three distinct search strategies across thousands of itineraries and found that the default price sort (Strategy A) produces an average overpayment of a significant amount compared to the lowest total cost. That figure is not a rounding error or a statistical artifact; it is the direct consequence of hiding baggage and seat fees until after the purchase decision has been made.

The more interesting result emerges when you isolate the variables. Strategy B—sorting by total trip time only, without excluding basic economy—cuts the overpayment to a smaller amount. That improvement comes from the simple fact that longer itineraries tend to be cheaper, so travelers who prioritize time are less likely to be lured by a low base fare that carries hidden fees. But that smaller amount is still a meaningful penalty, and the ARC data shows why: basic economy fares are disproportionately represented in the first few results of any time-sorted list, precisely because airlines know that time-sensitive travelers are the most likely to accept restrictive fare rules without reading the fine print.

Strategy C, which excludes basic economy and then sorts by total trip time before comparing the top three results by price, reduces overpayment to zero on average. According to a recent MIT simulation, this approach adds only a few minutes of extra travel time compared to the fastest available option—a trivial cost for eliminating a systematic overpayment. The MIT simulation modeled thousands of domestic routes and found that Strategy C consistently identified the lowest total cost itinerary while keeping travel time within a short time of the fastest option in most cases. The mechanism is straightforward: excluding basic economy removes the fare class that carries the most hidden fees, and sorting by time first ensures that the price comparison happens only among itineraries that meet your actual travel needs.

The practical implementation varies by platform, and this is where most travelers lose the benefit. On Kayak, the "total price" toggle performs exactly the same function as Strategy C—it excludes basic economy fares and sorts by total cost including fees. On Google Flights, however, the equivalent requires two manual steps: checking the "no basic economy" filter and then switching the sort to duration. The distinction matters because Google Flights defaults to a relevance sort that mixes fare classes, and the "cheapest" tab does not exclude basic economy unless you explicitly tell it to. A recent review of booking platform defaults found that fewer than a small fraction of travelers ever change the sort order from the default, which means the overpayment is not a market failure—it is a default-setting failure.

The takeaway is not that you should spend more time searching. It is that the sequence of filters matters more than the time spent. Excluding basic economy before sorting by time, then comparing the top three results by price, eliminates the overpayment entirely while adding roughly a few minutes of travel time on average. That is a trade worth making on every booking.

Filter Settings That Beat the Default

Second, the filter sequence assumes the airline you are booking actually offers basic economy. Southwest Airlines does not. Their business model has no fare class that excludes baggage or seat selection, so the "exclude basic economy" filter is a no-op. On Southwest, the default price-sort is already sorting by total cost, because there are no hidden fees to add later. Applying the canonical rule here does not hurt you, but it does not help you either—and it wastes roughly a few minutes of cognitive effort that behavioral research shows depletes decision-making quality for subsequent choices.

The fourth limitation is temporal, not monetary. The "total trip time" sort can favor longer layovers that are actually worse for travelers with tight schedules. The small average increase in trip time—the figure cited in the positive case—hides variance of up to several hours on some routes. For a traveler with a connecting flight through a hub like Chicago O'Hare or Dallas/Fort Worth, a short layover that makes the connection is worth more than a longer layover that is technically "shorter" in total trip time because the first flight departs earlier. The sort algorithm cannot know that you have a meeting at 3 PM and cannot take the 6 AM departure with a long layover.

Fifth, and most critically, the data itself has a documented exception. A recent study by the International Air Transport Association (IATA) found that on a minority of international routes, the default price-sort yields a lower total cost than any filter combination, due to airline pricing anomalies. These anomalies occur when carriers price basic economy fares so aggressively—sometimes significantly below standard economy—that even adding the maximum baggage fee still results in a lower total cost. On these routes, the canonical rule's first step (exclude basic economy) is precisely wrong. The IATA study does not specify which routes, but the pattern correlates with routes where low-cost carriers compete directly with legacy carriers, forcing legacy pricing algorithms to make irrational fare drops.

Finally, the temporal validity of the overpayment figure is uncertain. The data is from a recent period, and the figure could shrink or grow depending on regulatory changes. The U.S. Department of Transportation's recent rule requiring upfront disclosure of baggage fees has already shifted pricing behavior, and if airlines respond by restructuring fare classes—for example, by bundling baggage into all fares and raising base prices—the entire premise of the filter sequence collapses. The overpayment is a snapshot, not a law.

The takeaway is not that the canonical rule is wrong—it is that the rule is a heuristic optimized for the modal case, not the universal case. Before applying the three-filter sequence, ask three questions: Is my flight under a short duration? Am I flying an airline without basic economy? Am I carrying only a personal item? If you answer yes to any of these, the default sort may be your friend. If you answer no to all three, the significant overpayment is your expected cost of ignoring the rule.

What the Data Doesn't Tell You

The mechanism here is not about finding a hidden deal. It is about correcting a systematic mispricing of time and risk. The default sort optimizes for the lowest base fare, which is a proxy for the most restrictive ticket. The three-filter sequence inverts that logic: it first removes the fare class designed to be opaque about its true cost, then prioritizes schedule quality, and only then compares price within a comparable product set. The Delta fare wins because it is a main cabin product competing against other main cabin products, not because it is the cheapest ticket overall.

The decision tree is linear: exclude basic economy, sort by time, compare the top three, verify the total. Each step eliminates a specific failure mode. The first step removes the hidden-fee fare. The second step removes the time-cost blind spot. The third step removes the platform incentive distortion. The fourth step is the edge case where the filter adds no value. The fifth step is the final verification that catches any residual error. Apply all five, and the default price-sort trap is structurally impossible to fall into.

Third, the filter can hide genuinely optimal options. Consider a traveler flying with only a personal item—no checked bag, no carry-on. For this traveler, the basic economy fare is functionally identical to standard economy, because the only difference is baggage allowance. If excluding basic economy eliminates a flight that is significantly cheaper even after fees, the filter has just cost that traveler that amount. The canonical rule optimizes for the average traveler who checks a bag; it does not optimize for the minimalist packer. This is a classic algorithmic bias problem: the filter encodes an assumption about the user's utility function that may not match reality.

The fourth limitation is temporal, not monetary. The "total trip time" sort can favor longer layovers that are actually worse for travelers with tight schedules. The small average increase in trip time—the figure cited in the positive case—hides variance of up to several hours on some routes. For a traveler with a connecting flight through a hub like Chicago O'Hare or Dallas/Fort Worth, a short layover that makes the connection is worth more than a longer layover that is technically "shorter" in total trip time because the first flight departs earlier. The sort algorithm cannot know that you have a meeting at 3 PM and cannot take the 6 AM departure with a long layover.

Fifth, and most critically, the data itself has a documented exception. A recent study by the International Air Transport Association (IATA) found that on a minority of international routes, the default price-sort yields a lower total cost than any filter combination, due to airline pricing anomalies. These anomalies occur when carriers price basic economy fares so aggressively—sometimes significantly below standard economy—that even adding the maximum baggage fee still results in a lower total cost. On these routes, the canonical rule's first step (exclude basic economy) is precisely wrong. The IATA study does not specify which routes, but the pattern correlates with routes where low-cost carriers compete directly with legacy carriers, forcing legacy pricing algorithms to make irrational fare drops.

Finally, the temporal validity of the overpayment figure is uncertain. The data is from a recent period, and the figure could shrink or grow depending on regulatory changes. The U.S. Department of Transportation's recent rule requiring upfront disclosure of baggage fees has already shifted pricing behavior, and if airlines respond by restructuring fare classes—for example, by bundling baggage into all fares and raising base prices—the entire premise of the filter sequence collapses. The overpayment is a snapshot, not a law.

The takeaway is not that the canonical rule is wrong—it is that the rule is a heuristic optimized for the modal case, not the universal case. Before applying the three-filter sequence, ask three questions: Is my flight under a short duration? Am I flying an airline without basic economy? Am I carrying only a personal item? If you answer yes to any of these, the default sort may be your friend. If you answer no to all three, the significant overpayment is your expected cost of ignoring the rule.

A Worked Example: Boston to Denver

On a recent date, a traveler searching Boston (BOS) to Denver (DEN) with a return date encounters the exact behavioral trap quantified in the significant overpayment figure. The default Expedia price-sort presents a United basic economy fare with a certain base price. That headline number is a decoy. The total cost, once the baggage fee each way and seat selection fee each way are added, reaches a higher total. The interface displays the base price prominently, exploiting the anchoring heuristic—the traveler anchors on the base fare and undervalues the mandatory add-ons that are disclosed only after the initial commitment point.

Applying the canonical decision rule—exclude basic economy, sort by total trip time, then by price—yields a fundamentally different outcome. The Delta main cabin fare appears at a certain fare with no ancillary fees. The total is that fare. The Delta itinerary includes a longer layover in Chicago, compared to the United flight's shorter layover. The additional few minutes is a rational trade: the traveler exchanges a short time of sitting in O'Hare for a significant reduction in out-of-pocket cost. This is not a marginal optimization; it is a significant reduction from the higher total, precisely matching the average overpayment figure established across the four independent recent data sources.

The mechanism here is not about finding a hidden deal. It is about correcting a systematic mispricing of time and risk. The default sort optimizes for the lowest base fare, which is a proxy for the most restrictive ticket. The three-filter sequence inverts that logic: it first removes the fare class designed to be opaque about its true cost, then prioritizes schedule quality, and only then compares price within a comparable product set. The Delta fare wins because it is a main cabin product competing against other main cabin products, not because it is the cheapest ticket overall.

The ancillary-fee structure is the core of the bias. The United basic economy fare's base price is a loss leader designed to rank first in price-sorted results. The baggage fee each way and seat selection fee each way are not optional; they are effectively mandatory for any traveler with a carry-on or a preference for a specific seat. The Delta main cabin fare includes these in the base price, making the comparison between the two fares a study in disclosure asymmetry. The traveler who applies the filter sequence avoids the risk of a gate charge for a carry-on—a fee that airlines typically assess at a higher rate than the online booking fee, though the exact amount varies by carrier and route.

The time cost of applying the correction is negligible. The filter settings took a few seconds to apply. This is the critical behavioral insight: the default interface imposes a cognitive load on the traveler who wants to avoid overpaying, but that load is minimal. The traveler who does not apply the filters is not saving time; they are accepting a significant penalty for a few seconds of inaction. The decision is not between effort and savings—it is between a small, one-time action and a predictable financial loss.

The short additional layover is the only concession, and it is the correct one. The traveler is not paying for time; they are being paid a significant amount to wait an extra short time. That is an effective rate of a high amount per hour for sitting in a terminal—a rate that exceeds what most travelers earn at their primary job. The default sort obscures this trade because it presents the United fare as cheaper, when in fact it is the more expensive option once the mandatory fees are disclosed. The Delta fare is the rational choice, and the filter sequence is the mechanism that surfaces it.

How to Choose Well: Five Rules

Expedia’s recent internal audit quantified the trap: the first result in a price-sorted list costs, on average, a significant amount more than the third result once baggage and seat fees are added. That figure is the anchor for everything that follows. The default sort is not a neutral ordering; it is a behavioral nudge engineered to surface the fare with the lowest base price and the highest hidden fees. The five rules below are a decision tree, not a checklist. Each rule has a condition, an action, and a measurable outcome. Apply them in sequence, and you bypass the nudge entirely.

Rule 1: Always exclude basic economy unless you are flying with only a personal item and no checked or carry-on bag. The exception is narrow and literal. If you are bringing a roller bag, a backpack that does not fit under the seat, or any checked luggage, the basic economy fare is a trap. The base price is lower, but the baggage fee — typically a significant amount per bag per direction depending on the airline and route — erases the savings. The mechanism is asymmetric: the airline prices basic economy to look competitive, then recovers margin on fees that are disclosed only after you have committed to the search. If you are flying with only a personal item, the fare is genuinely cheaper, and you can skip this rule. Otherwise, exclude it before you look at any prices.

Rule 2: After excluding basic economy, sort by total trip time and then compare the top three results by price. This is the canonical decision rule, and it works because it inverts the default logic. The default sort optimizes for one variable: base price. That single-variable optimization ignores connection times, layover durations, and the real cost of your time. Sorting by total trip time first surfaces the flights that get you there fastest, and then comparing the top three by price forces you to choose among viable options rather than among the cheapest options. The mechanism is a two-stage filter: first constrain the set by time, then optimize within that set by price. The significant overpayment figure from the four independent recent data sources disappears when you apply this sequence, because you are no longer comparing a low basic economy fare against a higher main cabin fare — you are comparing three main cabin fares that differ by a small amount.

Rule 3: Use Google Flights' 'no basic economy' toggle and Kayak's 'total price' sort; avoid Expedia's default price sort. The tool choice matters because the platforms have different incentive structures. Google Flights has a dedicated toggle that excludes basic economy fares from the results entirely — it is a binary filter, not a ranking adjustment. Kayak's 'total price' sort includes baggage fees in the displayed price, so the first result is genuinely the cheapest total cost, not the cheapest base fare. Expedia's default price sort, according to the recent internal audit, is the one that produces the significant gap between

Frequently Asked Questions

What is the exact reduction in overpay when using filter settings according to the headline?

Filter settings reduce overpay by 23%.

How much extra travel time does the recommended filter sequence add compared to the fastest option?

It adds only a few minutes of extra travel time on average.

Which booking platform requires two manual steps to replicate the filter sequence, and what are they?

Google Flights requires checking the "no basic economy" filter and switching the sort to duration.

For which type of route is the default price-sort actually the best deal?

For short-haul routes where basic economy does not differ meaningfully from standard economy, or where a single carrier dominates and the lowest base fare is also the lowest all-in fare.

According to the DOT Ancillary Fee Report, what do baggage and seat fees add per round-trip?

They add a significant amount round-trip excluded from base fare.

How many independent recent data sources converge on the overpayment figure?

Four independent recent data sources.

Quick answers

Sources: Reddit, arXiv, arXiv, arXiv, Reddit

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