Flight profile · Delta Air Lines
DL423
Atlanta (ATL) to Salt Lake City (SLC) · scheduled 1:59 PM – 4:15 PM
How DL423 performs
1,101 operations, July 2023 – July 2026.
DL423 arrived on time 86.2% of the time, against 83.5% for all ATL → SLC flights, so this departure is 2.7 percentage points better than the route as a whole. Against Delta Air Lines’ own flights on this route it is 2.6 points better.
Source: US DOT Bureau of Transportation Statistics · 1,101 operations, July 2023 – July 2026 · If DL423 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where DL423 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| DL423 | 86.2% | 0.45% | -8 min | 2.7% | 1,101 |
| Delta Air Lines on ATL → SLC | 83.6% | 0.53% | -8 min | 5.0% | 9,161 |
| All ATL → SLC flights | 83.5% | 0.54% | -8 min | 5.0% | 9,222 |
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026
Why DL423 runs late
Where US DOT attributed the delay minutes on this flight.
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for DL423 on ATL → SLC. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies DL423 comes in late, and what that does to the departure.
The aircraft flying DL423 came in 15 or more minutes late on 8% of the departures where its previous flight is known. There are not enough departures in both groups to say how the flight left after a late one and after an on-time one.
Each departure is matched to the flight the same aircraft flew into ATL just before it, using the tail number in the DOT file, 1,056 of 1,098 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late |
|---|---|
| DL423 | 8% |
| Network, same turn | 17% |
The schedule leaves a normal turn: enough time to clean and board if the aircraft is on time, little to spare if it is not.
The network row is every flight with a scheduled turn of 60 to 89 minutes. How often DL423’s aircraft landed 15 or more minutes late is lower than the network’s. There are not enough departures in both groups to compare how it left.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
From pushback to gate
When it leaves ATL late, does that still matter by the time it reaches SLC?
DL423 pushes back an average of 5.7 minutes late and reaches the gate at SLC an average of 1.6 minutes early. The 7.4 minutes between those two figures are slack the published schedule already carries, which is why a late pushback on this flight does not reliably become a late arrival. It spends 15.8 minutes on the taxiways at ATL, 1.0 minutes longer than a typical ATL departure in the same hour.
On arrival at SLC, DL423 spends 8.4 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 1.4 minutes longer than a typical SLC arrival (7.1 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached SLC. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 50,600 departures from ATL scheduled in the clock hour DL423 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at SLC (355,118 flights), not just DL423’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026
The hour it leaves ATL
Part of any flight’s record belongs to the clock rather than to the flight. DL423 has one departure time, so this is what that time is worth.
On-time arrival rate. 50,600 departures from ATL are scheduled in the 1 PM–2 PM hour over the period, against 1,012,247 across the whole day.
DL423 is scheduled out of ATL at 1:59 PM, in the 1 PM–2 PM bank. Departures from ATL in that hour arrive on time 81.5% of the time against 78.7% across the airport’s whole day, so the hour DL423 leaves in is an ordinary one for ATL and explains nothing about its record either way.
The two airport figures cover every departure from ATL to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Hours below 120 departures are not scored.
By day of week
Does DL423 run worse on particular days?
Wednesday is historically the most reliable day and Sunday the least, a gap of 9.0 percentage points.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Days with fewer than 120 operations are not scored.
Other routes DL423 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| ATL→XNA Atlanta to Fayetteville/Springdale/Rogers | November 4, 2023 | 1 | — |
| DFW→LGA Dallas–Fort Worth to New York | October 29, 2023 – November 3, 2023 | 6 | — |
| ATL→SAN Atlanta to San Diego | October 9–27, 2023 | 19 | — |
| SAN→ATL San Diego to Atlanta | October 9–27, 2023 | 19 | — |
Because the same number has served different journeys, the statistics above describe only the route DL423 currently operates. Blending them would produce an average of two different flights.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
23 min late
against a median of 8 min early
Percentiles over 1,101 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| DL830 | Delta Air Lines | 90.6% | 8 min early | 1,115 |
| DL387 | Delta Air Lines | 90.5% | 10 min early | 1,060 |
| DL663 | Delta Air Lines | 88.8% | 11 min early | 1,021 |
| DL423 this flight | Delta Air Lines | 86.2% | 8 min early | 1,101 |
| DL526 | Delta Air Lines | 81.4% | 9 min early | 1,126 |
| DL653 | Delta Air Lines | 80.9% | 5 min early | 1,124 |
| DL660 | Delta Air Lines | 76.7% | 5 min early | 1,104 |
| DL453 | Delta Air Lines | 74.0% | 3 min early | 950 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. DL423 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 1,101 records of DL423 operating ATL → SLC, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
Analysis last recomputed