Flight number record

YX 4721

Republic Airways · Boston to New York

Route: BOS → JFK
Departs: 11:55
Flights: 283
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s YX 4721, check with Republic Airways. Republic Airways flies under contract for larger airlines, so a ticket for this flight may show a different airline code and number.

YX 4721 lands a B−, level with the national rate of 77.6%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 283 flights, with a median arrival 9 minutes early.

On time

77.4%

Arrivals under 15 minutes late, of 274 completed flights

Avg delay

66 min

Across delayed arrivals only, not all flights

Cancelled

3.18%

National rate is 1.81%

1 hour+ late

8.8%

National rate is 8.1%

These figures cover 283 flights between July 2025 and June 2026. Beyond the headline rate, 8.8% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Schedule

When YX 4721 flies

YX 4721 flies BOS to JFK without a single fixed slot. Its most common scheduled departure was 11:55, used on 47 of 283 flights, with 11:34 (45 flights) and 13:00 (33 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 11:5547 flights16.6%
Departs 11:3445 flights15.9%
Departs 13:0033 flights11.7%

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 11:55 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and YX 4721 runs level with that at 77.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

YX 4721 next to BOS to JFK

Every carrier on BOS to JFK combined arrived on time 75.5% of the time across 5,738 flights, so YX 4721 is 2 points ahead of it. Republic flew 2,915 flights on the same city pair under all its flight numbers, including this one, and those ran 75.1% on time. Across its whole network Republic Airways managed 78.5%, close to this flight's figure.

YX 4721 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
YX 4721thin sample	283	77.4%	66 min	3.18%	B−
All Republic Airways on BOS–JFK	2,915	75.1%	66 min	5.01%	B−
All carriers on BOS–JFK	5,738	75.5%	73 min	4.55%	B−
Republic Airways, whole network	361,482	78.5%	72 min	4.08%	B−

Across the year

YX 4721 quarter by quarter

Quarter by quarter YX 4721 held fairly steady: 82.8% in Jul–Sep 2025, 76.2% in Oct–Dec 2025, 76.2% in Jan–Mar 2026 and 74.0% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202564 flights82.8%
Oct–Dec 202584 flights76.2%
Jan–Mar 202685 flights76.2%
Apr–Jun 202650 flights74.0%

Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, YX 4721 did best on Friday at 87.2% on time and worst on Thursday at 71.8%. Each day rests on about 40 flights, so a gap of 15 points is worth noticing but could still narrow in another year.

Delay causes

Why YX 4721 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 58% of the 4,117 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.

Late-arriving aircraft
58%
National Airspace System
24%
Carrier
17%
Extreme weather
2%

58% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 4,117 reported delay minutes here, that single category outweighs weather by 34 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 4,117 delay minutes reported on YX 4721.

Cancellations run at 3.18%, against 1.81% nationally. That is about one flight in 30 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and routes

What a delay on this flight costs

8.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.

The same number turns up on four other city pairs in the data, including DCA to ORF (24), ORF to DCA (24) and BOS to DCA (6), but none flew often enough under YX 4721 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to BOS to JFK only.

One caution: this is a thin sample. 283 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 YX 4721

For a booking, the cancellation rate is the figure to plan around on YX 4721: 3.18% of its 283 scheduled flights did not operate. A late arrival costs about an hour, but a cancellation costs the day, so leave a later option open.

Where to go next

A flight number here means Republic Airways’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