Flight number record

DL 2173

Delta Air Lines · Boise to Salt Lake City

Route: BOI → SLC
Departs: 06:00
Flights: 354
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s DL 2173, check with Delta Air Lines.

DL 2173 earns an A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 13 points better than the national rate of 77.3%. When something does go wrong the average delay runs close to two hours. That rests on 354 flights, with a median arrival 9 minutes early.

Set against the rest of the country, DL 2173's record is 13 points better than the US average of 77.3%. That gap is worth roughly 129 fewer late arrivals for every thousand flights.

On time

90.2%

Arrivals under 15 minutes late, of 348 completed flights

Avg delay

105 min

Across delayed arrivals only, not all flights

Cancelled

1.69%

National rate is 1.89%

1 hour+ late

2.9%

National rate is 8.3%

These figures cover 354 flights between September 2025 and August 2026. The median arrival is 9 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

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Schedule

When DL 2173 flies

DL 2173 flies BOI to SLC without a single fixed slot. Its most common scheduled departure was 06:00, used on 261 of 354 flights, with 05:45 (38 flights) next.

Departs 06:00261 flights73.7%
Departs 05:4538 flights10.7%

Scale runs 0% to 100%.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 2173 runs level with that at 90.2%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

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Against the route

DL 2173 next to BOI to SLC

Every carrier on BOI to SLC combined arrived on time 91.1% of the time across 1,732 flights, so DL 2173 is about level with it. Delta flew 1,219 flights on the same city pair under all its flight numbers, including this one, and those ran 89.4% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 9 points.

DL 2173 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 2173thin sample	354	90.2%	105 min	1.69%	A
All Delta Air Lines on BOI–SLC	1,219	89.4%	87 min	1.31%	A
All carriers on BOI–SLC	1,732	91.1%	84 min	0.98%	A+
Delta Air Lines, whole network	1,039,517	81.1%	71 min	1.74%	B

Across the year

DL 2173 quarter by quarter

DL 2173 did not run the same all year. Its best quarter was Jul–Sep 2025 at 96.7% on time and its weakest Jan–Mar 2026 at 82.8%, a swing of 14 points on roughly 71 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Jul–Sep 202530 flights96.7%
Oct–Dec 202592 flights89.9%
Jan–Mar 202687 flights82.8%
Apr–Jun 202688 flights91.8%
Jul–Sep 202657 flights96.5%

Scale runs 75% to 100%.

By weekday, DL 2173 ranged from 86.0% on Monday to 93.9% on Friday. With about 51 flights behind each day, a spread of 8 points is inside normal variation, so the day you fly is not worth changing for this flight.

Arrival by arrival

How late DL 2173 runs when it is late

DL 2173 often beats the schedule: 100 of 348 completed flights, 29%, arrived 15 minutes or more early. The 34 late arrivals split 16 under half an hour, 8 between 30 and 60 minutes, and 10 an hour or more.

15+ min early100 flights28.7%
Within 15 min214 flights61.5%
15–29 min late16 flights4.6%
30–59 min late8 flights2.3%
1–2 hours late3 flights0.9%
2+ hours late7 flights2.0%

Scale runs 0% to 100%.

Share of 348 completed flights by arrival against schedule.

Only 18 of 348 completed flights left 15 minutes late or more, too few to say how often the time is made up.

The worst days

Worst days for DL 2173

The latest arrival of the period was on 27 October 2025, 12 hours 1 minute behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on five of the five worst days.

The latest arrivals of DL 2173 in the period
Date	Arrived late by	Largest filed cause
27 October 2025	12 hours 1 minute	Carrier
13 November 2025	8 hours 8 minutes	Carrier
6 January 2026	6 hours 10 minutes	Carrier
15 March 2026	5 hours 43 minutes	Carrier
19 May 2026	4 hours 41 minutes	Carrier

Delay causes

Why DL 2173 runs late

Carrier accounts for 83% of the 3,573 delay minutes carriers reported here, and the remaining four split what is left.

Carrier
83%
National Airspace System
16%
Late-arriving aircraft
1%

The largest share of delay minutes, 83%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,962 of the 3,573 delay minutes reported here. The split is drawn from 3,573 delay minutes reported on DL 2173.

Cancellations sit at 1.69% against a national 1.89%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

Badly late arrivals are rare here: only 2.9% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

Every one of the 354 flights under DL 2173 in the data flew BOI to SLC. The number was not reused on any other city pair, which makes this a clean record of one route.

One caution: this is a thin sample. 354 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking DL 2173

For a booking, read DL 2173 as 90.2% on time with 1.69% cancelled over 354 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures