Apparatus

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sensors Mode-S transponder

AC0B61

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N87507 · BOEING 737-800 · operated by UNITED AIRLINES INC

Hex
AC0B61
Octal
53005541
Decimal
11,275,105
Country
US
Tail
N87507
Type
B738
No current signal · last broadcast 18d ago
Flights observed
376
Distinct callsigns
20
Country
US
Last broadcast
18d ago

Last known position

Most recent position reported by Mode-S AC0B61.

Country allocation

The ICAO 24-bit address AC0B61 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
UAL1405 - 7 2026-06-23
UAL1408 - 5 2026-06-23
UAL452 United Airlines 4 2026-05-23
UAL364 United Airlines 4 2026-05-23
UAL2853 United Airlines 4 2026-05-17
UAL2090 United Airlines 4 2026-05-13
UAL1439 United Airlines 4 2026-04-29
UAL1113 United Airlines 4 2026-06-11
UAL2493 United Airlines 3 2026-06-16
UAL2236 United Airlines 3 2026-05-07
UAL2185 - 3 2026-06-14
UAL2086 United Airlines 3 2026-06-19
UAL204 United Airlines 3 2026-04-27
UAL1811 - 3 2026-06-25
UAL1776 United Airlines 3 2026-04-19
UAL1734 United Airlines 3 2026-06-09
UAL1651 United Airlines 3 2026-04-28
UAL1646 United Airlines 3 2026-06-16
UAL1325 United Airlines 3 2026-06-03
UAL1278 United Airlines 3 2026-04-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-06-26 UAL3883 - Jun 26, 04:24 UTCJun 26, 05:35 UTC1h 10m
2026-06-26 UAL2675 MCO → ORD Jun 26, 00:05 UTCJun 26, 02:40 UTC2h 35m
2026-06-25 UAL1811 - Jun 25, 20:34 UTCJun 25, 21:15 UTC40m
2026-06-25 UAL1811 ORD → MCO Jun 25, 18:14 UTCJun 25, 20:17 UTC2h 3m
2026-06-25 UAL1811 ORD → MCO Jun 25, 18:15 UTCJun 25, 21:15 UTC3h 0m
2026-06-25 UAL1310 LGA → ORD Jun 25, 14:38 UTCJun 25, 16:05 UTC1h 27m
2026-06-25 UAL1310 - Jun 25, 14:24 UTCJun 25, 16:14 UTC1h 50m
2026-06-25 UAL2617 ORD → LGA Jun 25, 11:10 UTCJun 25, 12:44 UTC1h 35m
2026-06-25 UAL2183 LGA → ORD Jun 25, 03:44 UTCJun 25, 05:44 UTC2h 0m
2026-06-24 UAL371 - Jun 24, 23:40 UTCJun 25, 01:14 UTC1h 35m
2026-06-24 UAL2199 LGA → DEN Jun 24, 18:41 UTCJun 24, 20:11 UTC1h 30m
2026-06-24 UAL2199 LGA → DEN Jun 24, 18:34 UTCJun 24, 20:30 UTC1h 55m
2026-06-24 UAL669 ORD → LGA Jun 24, 15:29 UTCJun 24, 17:05 UTC1h 35m
2026-06-24 UAL1887 LGA → ORD Jun 24, 11:05 UTCJun 24, 13:05 UTC2h 0m
2026-06-24 UAL1747 - Jun 24, 00:25 UTCJun 24, 03:24 UTC3h 0m
2026-06-23 UAL1405 - Jun 23, 18:45 UTCJun 23, 20:40 UTC1h 55m
2026-06-23 UAL1408 - Jun 23, 14:59 UTCJun 23, 16:59 UTC2h 0m
2026-06-23 UAL1409 - Jun 23, 10:29 UTCJun 23, 12:15 UTC1h 45m
2026-06-23 UAL1409 ORF → IAH Jun 23, 10:33 UTCJun 23, 13:18 UTC2h 45m
2026-06-23 UAL2439 RDU → ORF Jun 23, 05:00 UTCJun 23, 05:39 UTC40m
2026-06-23 UAL2439 - Jun 23, 00:24 UTCJun 23, 03:29 UTC3h 5m
2026-06-22 UAL2674 - Jun 22, 18:19 UTCJun 22, 21:54 UTC3h 35m
2026-06-22 UAL2674 LGA → IAH Jun 22, 18:16 UTCJun 22, 21:59 UTC3h 43m
2026-06-22 UAL2249 PHX → SFO Jun 22, 13:49 UTCJun 22, 16:45 UTC2h 55m
2026-06-22 UAL2249 PHX → SFO Jun 22, 13:22 UTCJun 22, 16:43 UTC3h 21m
2026-06-22 UAL631 - Jun 22, 07:40 UTCJun 22, 11:19 UTC3h 40m
2026-06-22 UAL1359 - Jun 22, 01:29 UTCJun 22, 06:00 UTC4h 30m
2026-06-21 UAL1867 - Jun 21, 23:10 UTCJun 21, 23:34 UTC25m
2026-06-21 UAL1867 - Jun 21, 21:39 UTCJun 21, 22:15 UTC35m
2026-06-21 UAL1919 - Jun 21, 18:25 UTCJun 21, 20:09 UTC1h 45m
2026-06-21 UAL1524 - Jun 21, 13:15 UTCJun 21, 16:19 UTC3h 5m
2026-06-21 UAL641 ATL → IAD Jun 21, 09:44 UTCJun 21, 11:05 UTC1h 20m
2026-06-21 UAL2110 - Jun 21, 00:10 UTCJun 21, 01:39 UTC1h 30m
2026-06-20 UAL1405 - Jun 20, 20:25 UTCJun 20, 22:14 UTC1h 50m
2026-06-20 UAL1405 BZE → IAH Jun 20, 20:11 UTCJun 20, 22:21 UTC2h 10m
2026-06-20 UAL1408 - Jun 20, 15:34 UTCJun 20, 16:00 UTC25m
2026-06-20 UAL1408 IAH → BZE Jun 20, 15:35 UTCJun 20, 17:33 UTC1h 58m
2026-06-20 UAL532 - Jun 20, 11:34 UTCJun 20, 13:14 UTC1h 40m
2026-06-20 UAL532 ATL → IAH Jun 20, 11:19 UTCJun 20, 13:16 UTC1h 57m
2026-06-20 UAL2110 - Jun 20, 01:24 UTCJun 20, 03:09 UTC1h 45m
2026-06-19 UAL2103 - Jun 19, 14:59 UTCJun 19, 20:40 UTC5h 40m
2026-06-19 UAL2205 - Jun 19, 10:39 UTCJun 19, 12:54 UTC2h 15m
2026-06-19 UAL2086 EWR → ATL Jun 19, 02:04 UTCJun 19, 04:04 UTC2h 0m
2026-06-19 UAL2086 EWR → ATL Jun 19, 02:05 UTCJun 19, 04:08 UTC2h 3m
2026-06-18 UAL1326 - Jun 18, 23:15 UTCJun 18, 23:50 UTC35m
2026-06-18 UAL2270 - Jun 18, 20:05 UTCJun 18, 21:45 UTC1h 40m
2026-06-18 UAL2375 - Jun 18, 16:05 UTCJun 18, 18:05 UTC2h 0m
2026-06-17 UAL1525 - Jun 17, 21:35 UTCJun 18, 01:45 UTC4h 10m
2026-06-17 UAL1129 EWR → SEA Jun 17, 19:40 UTCJun 17, 20:20 UTC40m
2026-06-17 UAL466 - Jun 17, 14:30 UTCJun 17, 15:30 UTC1h 0m

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 N87507 page for operator, model, and routing details .

Mode-S AC0B61 frequently asked

What is Mode-S code AC0B61?
AC0B61 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N87507.
Where is Mode-S AC0B61 registered?
Mode-S code AC0B61 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 AC0B61 broadcasting right now?
No active broadcast right now. Last signal was 18d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AC0B61, octal 53005541, decimal 11,275,105.
What flights does AC0B61 operate?
Mode-S AC0B61 has broadcast 20 distinct callsigns, including UAL1405, UAL1408, UAL452, UAL364, UAL2853.