Flight number record

DL 2173

Delta Air Lines · Boise to Salt Lake City

Route: BOI → SLC
Departs: 06:00
Flights: 359
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 77.6%. When something does go wrong the average delay runs close to two hours. That rests on 359 flights, with a median arrival 8 minutes early.

Set against the rest of the country, DL 2173's record is 13 points better than the US average of 77.6%. That gap is worth roughly 133 fewer late arrivals for every thousand flights.

On time

90.9%

Arrivals under 15 minutes late, of 353 completed flights

Avg delay

103 min

Across delayed arrivals only, not all flights

Cancelled

1.67%

National rate is 1.81%

1 hour+ late

2.3%

National rate is 8.1%

These figures cover 359 flights between July 2025 and June 2026. The median arrival is 8 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.

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 227 of 359 flights, with 05:45 (68 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 06:00227 flights63.2%
Departs 05:4568 flights18.9%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

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 90.9%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

DL 2173 next to BOI to SLC

Every carrier on BOI to SLC combined arrived on time 92.0% of the time across 1,740 flights, so DL 2173 is about level with it. Delta flew 1,223 flights on the same city pair under all its flight numbers, including this one, and those ran 90.5% on time. Across its whole network Delta Air Lines managed 81.6%, 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	359	90.9%	103 min	1.67%	A
All Delta Air Lines on BOI–SLC	1,223	90.5%	93 min	1.31%	A
All carriers on BOI–SLC	1,740	92.0%	85 min	0.98%	A+
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	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 98.9% on time and its weakest Jan–Mar 2026 at 82.8%, a swing of 16 points on roughly 90 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 202592 flights98.9%
Oct–Dec 202592 flights89.9%
Jan–Mar 202687 flights82.8%
Apr–Jun 202688 flights91.8%

Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, DL 2173 ranged from 87.8% on Tuesday to 94.0% on Friday. With about 51 flights behind each day, a spread of 6 points is inside normal variation, so the day you fly is not worth changing for this flight.

Delay causes

Why DL 2173 runs late

One category carries most of the weight here. Carrier accounts for 82% of the 3,289 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Carrier
82%
National Airspace System
17%
Late-arriving aircraft
1%

The largest share of delay minutes, 82%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 2,698 of the 3,289 delay minutes reported here. The split is drawn from 3,289 delay minutes reported on DL 2173.

Cancellations sit at 1.67% against a national 1.81%, 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 2.3% land an hour or more behind schedule, against 8.1% 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 359 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. 359 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 90.9% on time with 1.67% cancelled over 359 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures