Tier5 (observed) vs Spire (scheduled)

Both claim to be "flight cycles." Tier5 is assembled purely from observed ADS-B positions; Spire is a commercial schedule registry. 7-day overlap, 2026-06-03 … 06-09.

1,198,285Tier5 cycles

730,967Spire flights

Tier5 sees 64% more — it captures GA, military & non-commercial traffic absent from Spire's airline registry.

452,403exact route matches

61.9%of Spire confirmed

Legs agreeing on (aircraft, departure, arrival). Tier5 independently confirms 61.9% of Spire's schedule from raw observation.

+18.0mmedian takeoff − schedule

25.2mmean

On 399,231 matched legs, the gap between Tier5's observed takeoff and Spire's scheduled departure — i.e. the real departure-delay curve. The two datasets cross-validate.

Daily volume — Tier5 cycles vs Spire flights

Aircraft overlap & route confirmation (per day)

Date	Tier5 cycles	closed	Spire flights	AC Tier5	AC Spire	AC both	route match
06-03	181,455	173,860	102,768	55,170	25,931	22,461	62,141
06-04	185,258	177,828	106,511	55,702	26,220	22,779	65,212
06-05	181,730	173,924	109,057	55,201	26,311	22,807	65,626
06-06	156,278	149,289	99,977	48,194	25,343	22,057	60,953
06-07	158,302	151,039	103,569	49,462	25,499	22,123	63,439
06-08	168,349	161,421	104,927	50,586	25,614	22,130	65,891
06-09	166,913	159,902	104,158	51,100	25,958	22,359	69,141

Departure-delay distribution (matched legs)

Percentiles of (Tier5 observed takeoff − Spire scheduled), minutes.

Sample confirmed legs

Aircraft	Route	delay
0d0ec2	MMMY → MMMX	+39m
4d2265	LEBL → EGNT	+13m
48c225	EGNT → LHBP	-1m
8851e5	VTBS → VAAH	+28m
4ca647	EBCI → LIMF	+32m
aad780	EDDM → KIAH	+22m

Each: same airframe + same departure/arrival airport in both datasets, with the observed-vs-scheduled gap.

Verdict — who wins?

Completeness of volume → Tier5. It records 64% more flights and ~2× the distinct aircraft, because it observes everything that transmits ADS-B, not just scheduled airline service.
Schedule completeness & named routes → Spire. Near-100% of legs carry a clean departure/arrival ICAO + airline + scheduled time; Tier5 must infer endpoints from nearest-airport and leaves 60.6% of its closed cycles unmatched (regional/oceanic gaps, nearest-airport ambiguity).
Actual timing & truth-on-the-ground → Tier5. Spire's actual takeoff time is present only ~10% of the time; Tier5 observes it directly. Their +18.0 min median offset is the real delay signal.
Conclusion: they're complementary, not rivals — Spire answers "what was planned," Tier5 answers "what actually flew, and when." Fused on hex, each covers the other's blind spot.