Flight number record
YX 5604
Republic Airways · Memphis to Boston
- Route
- MEM → BOS
- Departs
- 06:05
- Flights
- 295
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s YX 5604, 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 5604 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 14 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 295 flights, with a median arrival 15 minutes early.
Set against the rest of the country, YX 5604's record is 14 points better than the US average of 77.3%. That gap is worth roughly 141 fewer late arrivals for every thousand flights.
Key figures
On time
91.4%
Arrivals under 15 minutes late, of 292 completed flights
Avg delay
115 min
Across delayed arrivals only, not all flights
Cancelled
0.68%
National rate is 1.89%
1 hour+ late
4.1%
National rate is 8.3%
These figures cover 295 flights between September 2025 and August 2026. The median arrival is 15 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 YX 5604 flies
YX 5604 flies MEM to BOS without a single fixed slot. Its most common scheduled departure was 06:05, used on 122 of 295 flights, with 06:00 (92 flights) next.
- Departs 06:05122 flights41.4%
- Departs 06:0092 flights31.2%
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 06:05 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and YX 5604 runs 2 points better at 91.4%. 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
YX 5604 next to MEM to BOS
Across its whole network Republic Airways managed 78.1%, which this flight beats by 13 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| YX 5604thin sample | 295 | 91.4% | 115 min | 0.68% | A+ |
| All Republic Airways on MEM–BOSthin sample | 295 | 91.4% | 115 min | 0.68% | A+ |
| All carriers on MEM–BOSthin sample | 295 | 91.4% | 115 min | 0.68% | A+ |
| Republic Airways, whole network | 364,452 | 78.1% | 74 min | 4.55% | B− |
Across the year
YX 5604 quarter by quarter
Quarter by quarter YX 5604 held fairly steady: 93.3% in Jul–Sep 2025, 88.4% in Oct–Dec 2025, 94.5% in Apr–Jun 2026 and 91.7% in Jul–Sep 2026. A spread of 6 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights93.3%
- Oct–Dec 202586 flights88.4%
- Jan–Mar 202626 flights—
- Apr–Jun 202691 flights94.5%
- Jul–Sep 202662 flights91.7%
Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, YX 5604 did best on Friday at 100.0% on time and worst on Wednesday at 85.4%. Each day rests on about 42 flights, so a gap of 15 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late YX 5604 runs when it is late
YX 5604 often beats the schedule: 152 of 292 completed flights, 52%, arrived 15 minutes or more early. The 25 late arrivals split 9 under half an hour, 4 between 30 and 60 minutes, and 12 an hour or more.
- 15+ min early152 flights52.1%
- Within 15 min115 flights39.4%
- 15–29 min late9 flights3.1%
- 30–59 min late4 flights1.4%
- 1–2 hours late5 flights1.7%
- 2+ hours late7 flights2.4%
Scale runs 0% to 100%.
Share of 292 completed flights by arrival against schedule.
4 of 21 late departures made up the time and arrived on time, 19% of them. 8 flights left on time and still arrived late.
The worst days
Worst days for YX 5604
The latest arrival of the period was on 5 July 2026, 8 hours 31 minutes 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.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 5 July 2026 | 8 hours 31 minutes | Carrier |
| 30 November 2025 | 8 hours 2 minutes | Carrier |
| 14 March 2026 | 5 hours 7 minutes | Carrier |
| 7 September 2025 | 3 hours 54 minutes | Carrier |
| 21 June 2026 | 3 hours 43 minutes | Carrier |
Delay causes
Why YX 5604 runs late
Carrier accounts for 86% of the 2,868 delay minutes carriers reported here, and the remaining four split what is left.
- 86%Carrier
- 7%National Airspace System
- 7%Late-arriving aircraft
The largest share of delay minutes, 86%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,466 of the 2,868 delay minutes reported here. The split is drawn from 2,868 delay minutes reported on YX 5604.
Cancellations are rare at 0.68%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 4.1% 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.
The 1,139 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The same number turns up on three other city pairs in the data, including RDU to BOS (7), LGA to MEM (4) and LGA to ORD (3), but none flew often enough under YX 5604 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to MEM to BOS only.
One caution: this is a thin sample. 295 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 5604
For a booking, YX 5604 has one of the better records a US domestic flight can show: 91.4% on time and 0.68% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- Memphis International (MEM) delay statistics
- Boston Logan International (BOS) delay statistics
- Republic Airways on-time record
- Every Republic Airways flight number with a record
- The most and least reliable flight numbers in the US
- Worst months to fly in the US, ranked by the data
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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.