Apparatus

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sensors Mode-S transponder

AAB187

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N78866 · BOEING 757-300 · operated by UNITED AIRLINES INC

Hex
AAB187
Octal
52530607
Decimal
11,186,567
Country
US
Tail
N78866
Type
B753
No current signal · last broadcast 4h ago
Flights observed
342
Distinct callsigns
20
Country
US
Last broadcast
4h ago

Last known position

Most recent position reported by Mode-S AAB187.

Country allocation

The ICAO 24-bit address AAB187 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
UAL1431 - 20 2026-07-11
UAL2268 - 19 2026-07-13
UAL1221 - 18 2026-07-12
UAL2276 - 16 2026-07-05
UAL1718 - 15 2026-07-13
UAL373 - 12 2026-07-11
UAL1719 - 12 2026-07-13
UAL1509 - 9 2026-07-12
UAL2499 United Airlines 8 2026-05-19
UAL599 - 7 2026-07-13
UAL2282 - 7 2026-06-28
UAL2280 United Airlines 7 2026-05-13
UAL2087 - 7 2026-06-27
UAL1868 - 7 2026-07-10
UAL2475 United Airlines 6 2026-05-13
UAL1176 - 6 2026-07-09
UAL638 - 5 2026-07-03
UAL2814 - 5 2026-07-07
UAL1734 United Airlines 5 2026-05-11
UAL1495 United Airlines 5 2026-06-09

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 UAL599 IAD → DEN Jul 13, 22:10 UTCJul 14, 01:05 UTC2h 55m
2026-07-13 UAL2268 - Jul 13, 15:25 UTCJul 13, 20:05 UTC4h 40m
2026-07-13 UAL1719 - Jul 13, 12:25 UTCJul 13, 13:05 UTC40m
2026-07-13 UAL1719 - Jul 13, 08:15 UTCJul 13, 08:20 UTC5m
2026-07-13 UAL1718 - Jul 13, 05:15 UTCJul 13, 05:35 UTC20m
2026-07-13 UAL1718 - Jul 13, 00:25 UTCJul 13, 00:55 UTC30m
2026-07-12 UAL1221 - Jul 12, 17:10 UTCJul 12, 22:05 UTC4h 55m
2026-07-12 UAL1509 SFO → HNL Jul 12, 00:11 UTCJul 12, 05:02 UTC4h 51m
2026-07-12 UAL1509 - Jul 12, 00:10 UTCJul 12, 05:05 UTC4h 55m
2026-07-11 UAL373 - Jul 11, 21:30 UTCJul 11, 22:05 UTC35m
2026-07-11 UAL373 - Jul 11, 17:20 UTCJul 11, 17:40 UTC20m
2026-07-11 UAL1431 - Jul 11, 01:50 UTCJul 11, 02:05 UTC15m
2026-07-10 UAL1431 - Jul 10, 20:55 UTCJul 10, 21:25 UTC30m
2026-07-10 UAL1431 LAX → HNL Jul 10, 20:33 UTCJul 11, 02:06 UTC5h 33m
2026-07-10 UAL1868 - Jul 10, 13:45 UTCJul 10, 18:30 UTC4h 45m
2026-07-09 UAL347 DEN → IAD Jul 9, 20:10 UTCJul 9, 23:00 UTC2h 50m
2026-07-09 UAL2348 SFO → DEN Jul 9, 16:22 UTCJul 9, 18:26 UTC2h 4m
2026-07-09 UAL2348 SFO → DEN Jul 9, 16:25 UTCJul 9, 18:20 UTC1h 55m
2026-07-09 UAL1176 HNL → SFO Jul 9, 09:30 UTCJul 9, 14:23 UTC4h 53m
2026-07-09 UAL1176 HNL → SFO Jul 9, 09:30 UTCJul 9, 14:11 UTC4h 41m
2026-07-09 UAL1431 LAX → HNL Jul 9, 02:08 UTCJul 9, 07:32 UTC5h 24m
2026-07-09 UAL1431 - Jul 9, 02:15 UTCJul 9, 07:30 UTC5h 15m
2026-07-08 UAL3021 - Jul 8, 19:40 UTCJul 9, 00:35 UTC4h 55m
2026-07-08 UAL1431 - Jul 8, 01:35 UTCJul 8, 01:50 UTC15m
2026-07-07 UAL1431 - Jul 7, 20:40 UTCJul 7, 21:10 UTC30m
2026-07-07 UAL2814 ORD → LAX Jul 7, 14:18 UTCJul 7, 17:41 UTC3h 23m
2026-07-07 UAL2814 - Jul 7, 14:15 UTCJul 7, 17:50 UTC3h 35m
2026-07-06 UAL1777 SFO → ORD Jul 6, 22:54 UTCJul 7, 02:38 UTC3h 44m
2026-07-06 UAL1777 SFO → ORD Jul 6, 22:55 UTCJul 7, 02:35 UTC3h 40m
2026-07-06 UAL543 - Jul 6, 16:30 UTCJul 6, 20:25 UTC3h 55m
2026-07-06 UAL1375 JAX → EWR Jul 6, 01:45 UTCJul 6, 05:20 UTC3h 35m
2026-07-05 UAL1577 ORD → SFO Jul 5, 20:10 UTCJul 6, 00:05 UTC3h 55m
2026-07-05 UAL1941 - Jul 5, 14:10 UTCJul 5, 17:50 UTC3h 40m
2026-07-05 UAL2276 IAD → LAX Jul 5, 02:54 UTCJul 5, 08:06 UTC5h 12m
2026-07-05 UAL2276 - Jul 5, 03:15 UTCJul 5, 08:00 UTC4h 45m
2026-07-04 UAL2268 - Jul 4, 15:40 UTCJul 4, 20:10 UTC4h 30m
2026-07-04 UAL1719 KOA → LAX Jul 4, 08:28 UTCJul 4, 12:59 UTC4h 31m
2026-07-04 UAL1719 - Jul 4, 08:20 UTCJul 4, 08:25 UTC5m
2026-07-04 UAL1718 - Jul 4, 05:35 UTCJul 4, 05:40 UTC5m
2026-07-04 UAL1718 - Jul 4, 00:35 UTCJul 4, 01:05 UTC30m
2026-07-04 UAL1718 LAX → KOA Jul 4, 00:37 UTCJul 4, 05:41 UTC5h 4m
2026-07-03 UAL1221 PDX → EWR Jul 3, 22:15 UTCJul 3, 22:50 UTC35m
2026-07-03 UAL1221 PDX → EWR Jul 3, 18:05 UTCJul 3, 18:20 UTC15m
2026-07-03 UAL638 SFO → HNL Jul 3, 02:34 UTCJul 3, 07:06 UTC4h 32m
2026-07-03 UAL638 - Jul 3, 02:30 UTCJul 3, 03:00 UTC30m
2026-07-02 UAL2633 PHL → IAH Jul 2, 22:10 UTCJul 3, 00:25 UTC2h 15m
2026-07-02 UAL1604 SFO → BNA Jul 2, 18:10 UTCJul 2, 20:05 UTC1h 55m
2026-07-02 UAL2391 - Jul 2, 14:05 UTCJul 2, 16:15 UTC2h 10m
2026-07-01 UAL599 IAD → DEN Jul 1, 22:05 UTCJul 2, 01:20 UTC3h 15m
2026-07-01 UAL2268 - Jul 1, 15:25 UTCJul 1, 20:00 UTC4h 35m

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 N78866 page for operator, model, and routing details .

Mode-S AAB187 frequently asked

What is Mode-S code AAB187?
AAB187 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N78866.
Where is Mode-S AAB187 registered?
Mode-S code AAB187 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 AAB187 broadcasting right now?
No active broadcast right now. Last signal was 4h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AAB187, octal 52530607, decimal 11,186,567.
What flights does AAB187 operate?
Mode-S AAB187 has broadcast 20 distinct callsigns, including UAL1431, UAL2268, UAL1221, UAL2276, UAL1718.