Apparatus

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sensors Mode-S transponder

A721A4

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N559JB · AIRBUS A-320 · operated by UMB BANK NA TRUSTEE

Hex
A721A4
Octal
51620644
Decimal
10,953,124
Country
US
Tail
N559JB
Type
A320
No current signal · last broadcast 5h ago
Flights observed
151
Distinct callsigns
20
Country
US
Last broadcast
5h ago

Last known position

Most recent position reported by Mode-S A721A4.

Country allocation

The ICAO 24-bit address A721A4 falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States receives a permanent address from this block at the time of registration; the address stays with the airframe even if the aircraft is re-registered to a different operator within the country.

Callsign history 20 distinct

Callsign Airline Flights Last seen
JBU929 JetBlue Airways 5 2026-05-29
JBU154 JetBlue Airways 4 2026-05-24
JBU768 JetBlue Airways 3 2026-04-14
JBU2404 JetBlue Airways 3 2026-04-15
JBU1153 JetBlue Airways 3 2026-04-25
JBU1072 JetBlue Airways 3 2026-05-07
JBU98 JetBlue Airways 2 2026-05-19
JBU959 JetBlue Airways 2 2026-04-18
JBU928 JetBlue Airways 2 2026-05-29
JBU884 JetBlue Airways 2 2026-04-16
JBU879 - 2 2026-04-17
JBU8679 - 2 2026-04-25
JBU83 - 2 2026-04-15
JBU677 JetBlue Airways 2 2026-05-11
JBU613 JetBlue Airways 2 2026-05-05
JBU536 JetBlue Airways 2 2026-05-08
JBU438 JetBlue Airways 2 2026-04-17
JBU404 JetBlue Airways 2 2026-05-23
JBU391 JetBlue Airways 2 2026-05-17
JBU389 JetBlue Airways 2 2026-05-13

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-05-29 JBU929 BOS → JAX May 29, 20:20 UTCMay 29, 20:40 UTC20m
2026-05-29 JBU929 BOS → JAX May 29, 17:45 UTCMay 29, 18:10 UTC25m
2026-05-29 JBU929 BOS → JAX May 29, 17:45 UTCMay 29, 20:40 UTC2h 55m
2026-05-29 JBU928 SAN → BOS May 29, 13:05 UTCMay 29, 16:15 UTC3h 10m
2026-05-28 JBU1727 EWR → MCO May 28, 17:19 UTCMay 29, 16:15 UTC22h 57m
2026-05-28 JBU1727 EWR → MCO May 28, 17:20 UTCMay 28, 19:50 UTC2h 30m
2026-05-28 JBU2028 MCO → EWR May 28, 12:30 UTCMay 28, 14:35 UTC2h 5m
2026-05-27 JBU1695 MCO → SJO May 27, 14:35 UTCMay 27, 21:30 UTC6h 55m
2026-05-27 JBU2920 MIA → BOS May 27, 10:05 UTCMay 27, 12:40 UTC2h 35m
2026-05-27 JBU2919 BOS → SAN May 27, 01:05 UTCMay 27, 03:29 UTC2h 25m
2026-05-26 JBU1948 FLL → MCO May 26, 00:49 UTCMay 26, 22:59 UTC22h 11m
2026-05-25 JBU2096 CUN → FLL May 25, 15:17 UTCMay 26, 15:00 UTC23h 43m
2026-05-25 JBU2095 FLL → CUN May 25, 12:10 UTCMay 25, 13:25 UTC1h 15m
2026-05-24 JBU2276 FLL → PHL May 24, 19:00 UTCMay 24, 21:15 UTC2h 15m
2026-05-24 JBU2276 FLL → PHL May 24, 19:00 UTCMay 25, 16:40 UTC21h 40m
2026-05-24 JBU1739 SYR → FLL May 24, 14:10 UTCMay 24, 16:55 UTC2h 45m
2026-05-24 JBU1738 MCO → BDL May 24, 10:05 UTCMay 24, 12:30 UTC2h 25m
2026-05-24 JBU154 PBI → JFK May 24, 01:25 UTCMay 24, 02:00 UTC35m
2026-05-23 JBU154 PBI → JFK May 23, 23:40 UTCMay 23, 23:55 UTC15m
2026-05-23 JBU1608 STI → SJU May 23, 21:40 UTCMay 23, 21:50 UTC10m
2026-05-23 JBU1607 SJU → STI May 23, 18:50 UTCMay 23, 19:05 UTC15m
2026-05-23 JBU1903 JFK → SJU May 23, 13:45 UTCMay 23, 14:05 UTC20m
2026-05-23 JBU1903 JFK → SJU May 23, 11:10 UTCMay 23, 11:45 UTC35m
2026-05-23 JBU404 SJU → JFK May 23, 01:25 UTCMay 23, 02:15 UTC50m
2026-05-22 JBU404 SJU → JFK May 22, 23:05 UTCMay 22, 23:15 UTC10m
2026-05-22 JBU1453 FLL → SJU May 22, 21:40 UTCMay 22, 21:50 UTC10m
2026-05-22 JBU1453 FLL → SJU May 22, 19:45 UTCMay 22, 20:15 UTC30m
2026-05-22 JBU1799 LGA → MCO May 22, 16:20 UTCMay 22, 18:20 UTC2h 0m
2026-05-22 JBU1800 FLL → ORF May 22, 13:10 UTCMay 22, 15:00 UTC1h 50m
2026-05-21 JBU1800 FLL → ORF May 21, 14:36 UTCMay 22, 01:20 UTC10h 45m
2026-05-21 JBU1905 FLL → TPA May 21, 01:10 UTCMay 21, 01:55 UTC45m
2026-05-21 JBU1905 FLL → TPA May 21, 01:07 UTCMay 22, 01:00 UTC23h 54m
2026-05-20 JBU1454 PBI → JFK May 20, 22:10 UTCMay 20, 22:45 UTC35m
2026-05-20 JBU1454 PBI → JFK May 20, 20:25 UTCMay 20, 20:40 UTC15m
2026-05-20 JBU635 BOS → SFO May 20, 14:55 UTCMay 20, 19:05 UTC4h 10m
2026-05-19 JBU98 DEN → JFK May 19, 08:55 UTCMay 19, 13:00 UTC4h 5m
2026-05-19 JBU98 DEN → JFK May 19, 08:51 UTCMay 20, 00:15 UTC15h 24m
2026-05-19 JBU97 JFK → DEN May 19, 02:00 UTCMay 19, 06:45 UTC4h 45m
2026-05-18 JBU2884 MCO → JFK May 18, 21:25 UTCMay 18, 23:50 UTC2h 25m
2026-05-18 JBU934 SJU → MCO May 18, 19:00 UTCMay 18, 19:55 UTC55m
2026-05-17 JBU392 TPA → BOS May 17, 23:26 UTCMay 18, 23:00 UTC23h 34m
2026-05-17 JBU391 BOS → TPA May 17, 19:05 UTCMay 17, 22:10 UTC3h 5m
2026-05-17 JBU391 BOS → TPA May 17, 19:04 UTCMay 18, 19:00 UTC23h 56m
2026-05-17 JBU722 PBI → BOS May 17, 14:30 UTCMay 17, 17:10 UTC2h 40m
2026-05-17 JBU667 HPN → PBI May 17, 10:35 UTCMay 17, 12:55 UTC2h 20m
2026-05-16 JBU1695 MCO → SJO May 16, 14:09 UTCMay 17, 12:55 UTC22h 47m
2026-05-16 JBU634 SFO → BOS May 16, 02:30 UTCMay 17, 01:00 UTC22h 31m
2026-05-15 JBU929 BOS → JAX May 15, 17:40 UTCMay 15, 20:40 UTC3h 0m
2026-05-15 JBU929 BOS → JAX May 15, 17:35 UTCMay 16, 15:01 UTC21h 26m
2026-05-15 JBU928 SAN → BOS May 15, 15:45 UTCMay 15, 16:15 UTC30m

About Mode-S

A Mode-S transponder code (also called an "ICAO 24-bit address" or "hex code") is a 6-character hexadecimal identifier permanently assigned to an aircraft when it's first registered. Unlike callsigns (which change with each flight) or registrations (which can change if an aircraft is sold internationally), the Mode-S address stays with the airframe for the life of the aircraft in that country.

Every ADS-B transmission from an aircraft includes its Mode-S address, making it the most reliable way to identify a specific airframe. Flight-tracking services like Apparatus use the Mode-S address as the primary key for tying position broadcasts, callsigns, and ownership records together.

Prefer a tail-number view? See the N559JB page for operator, model, and routing details .

Mode-S A721A4 frequently asked

What is Mode-S code A721A4?
A721A4 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N559JB.
Where is Mode-S A721A4 registered?
Mode-S code A721A4 is allocated to United States (US). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is A721A4 broadcasting right now?
No active broadcast right now. Last signal was 5h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A721A4, octal 51620644, decimal 10,953,124.
What flights does A721A4 operate?
Mode-S A721A4 has broadcast 20 distinct callsigns, including JBU929, JBU154, JBU768, JBU2404, JBU1153.