The Anatomy of a Score
A proprietary algorithm that scores every flight across the factors that actually shape your trip.
DL301 (ATL-LAX)
Tue, Sep 22, 2026 · Delta Air Lines
Modern aircraft
A350-900, a recent build
Solid on-time record
Above the route average
Comfort seating costs more
Extra-legroom rows are upsold
Above average. Not bad at all.
Every number is sourced.
Every score pulls from live flight status feeds, years of Bureau of Transportation Statistics records on every US domestic route, FAA registry data covering over half a million aircraft, real-time airport weather, live local business data for what's actually near your gate, and our own airline fleet profiles covering seat specs and policies for the largest US carriers. All of it runs through a proprietary scoring engine that weighs each factor by how much it actually affects your trip.
The Five Components
Five categories, weighted differently based on what actually affects your flight.
Seat Quality
Seat pitch, width, and recline, plus how close you are to the galley and lavatory where the airline discloses it. This is the category we weight most heavily, it's the difference you actually feel in your body for the length of the flight.
Airlines rarely publish their own exact pitch and width numbers, that data mostly comes from third-party seat-map research. It's part of why we label our own seat data confirmed or estimated rather than presenting every number as equally precise. And exit-row seats can't fully recline on any airline, ever, that's an FAA safety rule so the person behind an emergency exit has a clear path out, not a cost-cutting choice by any particular carrier.
Flight Reliability
Twelve months of on-time performance, delays, and cancellations for your specific route and airline, pulled from federal aviation records. Weighted heavily, just behind seat comfort.
Aircraft Quality
The generation of aircraft you're flying, plus a few cabin extras like WiFi and power. Newer aircraft score higher. Age, seat count, and engine configuration come from the FAA's own aircraft registry, the same data source air traffic controllers use.
Airline Policy
Baggage fees, change and cancellation rules, and basic economy restrictions. Lighter weight than seat and reliability, but enough to catch you off guard if you skip it. Airline Policy also weighs a carrier's public track record with federal aviation regulators, including any documented enforcement actions.
Airport Experience
What's around your gate matters. We score every major US airport on nearby dining, shops, and services, pulled from live local business data, so you know what to expect before you land. It carries the lightest weight in the overall score today, but it's a real, current picture of the terminal, not a static guess.
These five categories are weighted the same for every traveler, so the same flight always scores the same no matter who is asking. That consistency is the point: it makes scores directly comparable across flights, airlines, and dates.
Which Airlines We Track
We track the top US airlines: those carrying at least 0.5% of U.S. domestic air travelers, the federal government's own threshold for individualized on-time-performance tracking. The current roster: Alaska, Allegiant, American, Delta, Frontier, JetBlue, Southwest, and United.
A carrier stays on that list only while you can book it and get a flight number under its own code. Hawaiian came off in September 2026 for exactly that reason: its HA code was retired in April 2026 and its flying now sells as Alaska. You can still fly Hawaiian aircraft and crews, and that flying is still counted here - it just arrives inside Alaska's numbers now.
Deeper Dives
Want a closer look at the data behind each score? These guides break down specific factors airline by airline.
Basic Economy Carry-On Rules
Which airlines let you bring a carry-on and which charge you: United's outright ban, Frontier and Allegiant's paid add-on, and the carriers that never restrict it.
Boarding Zones by Airline
How each carrier boards, from pre-boarding to Group 9. Know your zone before you get to the gate.
DOT Refund Rule
The government's new rules on when airlines owe you cash back for cancellations and significant changes.
Dynamic Bag Fees
Why checked bag prices vary by route, airline, and when you pay. The pricing logic behind the fees.
Southwest Bag Fees
What Southwest charges for checked bags now, and the two ways to still fly them free.
Which Airlines We Track
Why these carriers, the DOT reporting threshold, and why Hawaiian is no longer one of them.
Scoring Terminology
Plain-language definitions of the data points behind each score.
Enplanement+
A passenger who boards a flight - it's just DOT's word for "a passenger who got on a plane."
Used as the denominator to turn a raw complaint or bumping count into a fair rate (e.g. complaints per million passengers), so a huge airline like American isn't unfairly compared to a small one like Allegiant just because it flies more people.
DOT Enforcement Action+
When the U.S. Department of Transportation formally investigates an airline, finds it broke a rule, and issues a real penalty (a fine or a mandated refund). This is a matter of public record, not a customer opinion.
This is the strongest, most concrete signal we have that an airline actually violated a rule - much stronger evidence than a high complaint count, which could just mean the airline is bigger or more visible.
Denied Boarding / Bumping+
When more people show up for a flight than there are seats, and the airline has to hold someone back. "Voluntary" means someone agreed to give up their seat (usually for compensation); "involuntary" means the airline forced someone off without them agreeing.
A high involuntary rate signals an airline that overbooks aggressively and doesn't get enough volunteers - a real inconvenience risk for passengers.
Oversales / ATCR+
"Oversales" is DOT's technical name for the bumping problem above. The "ATCR" (Air Travel Consumer Report) is the DOT's own monthly/quarterly public report where this data - along with delays, complaints, and mishandled baggage - gets published per airline.
This is the primary authoritative source ScoreFlights uses for reliability and policy-track-record data - it's free, official, and updated regularly.
DOT Automatic Refund Rule+
A federal rule (effective October 2024) that requires airlines to automatically refund passengers when they're owed money - without the passenger having to ask for it first - for things like a canceled flight or a significant schedule change.
This is the baseline every airline in the U.S. is legally required to meet now, so "compliance" alone isn't very differentiating - the meaningful signal is whether an airline has actually been caught and penalized for NOT following it.
Refund Policy Quality Score+
ScoreFlights' own two-tier scoring of each airline's refund track record: +25 points if the airline has no documented DOT enforcement action; -15 points if DOT has formally penalized the airline for a refund-related violation.
Simplified from an original 3-tier design (which included a "proactive communication" middle tier) because there's no public dataset that reliably measures how "proactive" an airline's refund communication is - the score only claims what the data can actually support.
On-Time Performance+
The share of flights that arrive within 14 minutes of their scheduled gate time. The U.S. government (DOT) counts a flight as on time if it arrives 14 minutes or less after the schedule, and this is the standard used across ScoreFlights reliability data.
This is the single best predictor of whether your flight actually gets you where you are going when you expect to. It comes straight from official DOT reports, not from user reviews or anecdote.
Mishandled Baggage+
Bags that are delayed, damaged, or lost by the airline, reported as a rate per 1,000 passengers by DOT.
A low mishandled rate means the airline reliably gets your bag to the same airport you land at. It is one of the few official, apples-to-apples quality signals that is published for every U.S. airline.
DOT Complaints+
Formal complaints passengers file with the U.S. Department of Transportation about an airline, reported per 100,000 passengers.
Complaint volume is a rough but official signal of how much friction passengers actually experienced. Combined with enforcement actions, it helps separate airlines that mostly talk a good game from airlines that deliver.
Overweight Bag Fee+
The extra charge an airline applies when a checked bag weighs more than its standard limit (usually 50 pounds). These fees are typically flat per segment, not per mile, so they hit short hops and long hauls equally.
An overweight fee is a direct cost to you if you pack heavy. Airlines set these very differently, and the difference can be tens of dollars per bag per direction.
Oversize Bag Fee+
The extra charge an airline applies when a checked bag exceeds its standard size limits (usually 62 linear inches). Oversize items often must be checked at a special counter and may delay your bag or require a special tag.
An oversize fee is a direct cost to you if you fly with a large bag, skis, or similar gear. It is a separate charge from the overweight fee and both can apply to the same bag.
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