Apparatus

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sensors Mode-S transponder

AB540D

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N829UA · AIRBUS A-319 · operated by UNITED AIRLINES INC

Hex
AB540D
Octal
52652015
Decimal
11,228,173
Country
US
Tail
N829UA
Type
A319
No current signal · last broadcast Jul 26, 21:15 UTC
Flights observed
493
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:15 UTC

Last known position

Most recent position reported by Mode-S AB540D.

Country allocation

The ICAO 24-bit address AB540D 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
UAL2218 - 7 2026-07-01
UAL2467 United Airlines 6 2026-06-16
UAL1778 - 6 2026-07-03
UAL600 - 5 2026-07-03
UAL1305 - 5 2026-06-29
UAL738 - 4 2026-07-17
UAL652 United Airlines 4 2026-06-08
UAL482 - 4 2026-07-09
UAL451 - 4 2026-06-21
UAL412 United Airlines 4 2026-07-25
UAL2255 United Airlines 4 2026-07-23
UAL2190 - 4 2026-07-09
UAL2173 United Airlines 4 2026-05-26
UAL2130 United Airlines 4 2026-07-23
UAL2082 United Airlines 4 2026-05-20
UAL1813 United Airlines 4 2026-06-18
UAL1604 United Airlines 4 2026-05-24
UAL1469 - 4 2026-07-15
UAL1380 United Airlines 4 2026-06-08
UAL697 - 3 2026-07-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL2808 ORF → IAH Jul 26, 19:10 UTCJul 26, 21:15 UTC2h 5m
2026-07-26 UAL502 IAH → DCA Jul 26, 15:40 UTCJul 26, 18:05 UTC2h 25m
2026-07-26 UAL1366 IAD → DEN Jul 26, 12:45 UTCJul 26, 14:00 UTC1h 15m
2026-07-26 UAL1524 IAH → EWR Jul 26, 10:25 UTCJul 26, 11:10 UTC45m
2026-07-26 UAL2677 CLE → DEN Jul 26, 03:10 UTCJul 26, 03:45 UTC35m
2026-07-25 UAL1240 SAT → EWR Jul 25, 23:25 UTCJul 26, 01:50 UTC2h 25m
2026-07-25 UAL2842 SFO → DFW Jul 25, 19:10 UTCJul 25, 22:15 UTC3h 5m
2026-07-25 UAL822 DEN → GRR Jul 25, 12:15 UTCJul 25, 16:15 UTC4h 0m
2026-07-25 UAL412 SFO → MEX Jul 25, 10:35 UTCJul 25, 10:40 UTC5m
2026-07-25 UAL412 SFO → MEX Jul 25, 06:40 UTCJul 25, 08:35 UTC1h 55m
2026-07-25 UAL2097 SFO → EWR Jul 25, 03:25 UTCJul 25, 05:10 UTC1h 45m
2026-07-25 UAL543 IAH → MCO Jul 25, 00:50 UTCJul 25, 02:10 UTC1h 20m
2026-07-24 UAL1846 ORD → CMH Jul 24, 22:50 UTCJul 24, 23:25 UTC35m
2026-07-24 UAL1846 ORD → CMH Jul 24, 17:40 UTCJul 24, 19:50 UTC2h 10m
2026-07-24 UAL472 SFO → RDU Jul 24, 14:10 UTCJul 24, 16:10 UTC2h 0m
2026-07-23 UAL2130 DEN → PHL Jul 23, 23:55 UTCJul 24, 01:40 UTC1h 45m
2026-07-23 UAL696 RIC → DEN Jul 23, 19:45 UTCJul 23, 21:55 UTC2h 10m
2026-07-23 UAL1836 SEA → SFO Jul 23, 16:20 UTCJul 23, 18:15 UTC1h 55m
2026-07-23 UAL2255 MSO → DEN Jul 23, 14:45 UTCJul 23, 15:10 UTC25m
2026-07-23 UAL8173 SJU → EWR Jul 23, 13:15 UTCJul 23, 13:30 UTC15m
2026-07-23 UAL1602 MCO → DEN Jul 23, 02:55 UTCJul 23, 04:50 UTC1h 55m
2026-07-22 UAL1439 EWR → SFO Jul 22, 21:30 UTCJul 22, 22:10 UTC40m
2026-07-22 UAL1072 BJX → IAH Jul 22, 18:04 UTCJul 22, 19:45 UTC1h 41m
2026-07-22 UAL2118 IAH → BJX Jul 22, 15:20 UTCJul 22, 19:45 UTC4h 25m
2026-07-21 UAL425 MCO → EWR Jul 21, 15:50 UTCJul 21, 17:25 UTC1h 35m
2026-07-21 UAL425 MCO → EWR Jul 21, 15:55 UTCJul 21, 17:21 UTC1h 26m
2026-07-21 UAL1030 SAT → EWR Jul 21, 12:35 UTCJul 21, 14:10 UTC1h 35m
2026-07-21 UAL1030 SAT → EWR Jul 21, 12:39 UTCJul 21, 14:07 UTC1h 28m
2026-07-21 UAL2260 PHL → ORD Jul 21, 10:20 UTCJul 21, 11:10 UTC50m
2026-07-21 UAL1949 ORD → DCA Jul 21, 01:20 UTCJul 21, 02:05 UTC45m
2026-07-21 UAL1949 ORD → DCA Jul 21, 01:24 UTCJul 21, 02:02 UTC38m
2026-07-20 UAL1420 MCO → EWR Jul 20, 21:50 UTCJul 20, 23:40 UTC1h 50m
2026-07-20 UAL587 EWR → MSP Jul 20, 20:10 UTCJul 20, 20:45 UTC35m
2026-07-20 UAL2437 LGA → DEN Jul 20, 16:40 UTCJul 20, 17:45 UTC1h 5m
2026-07-20 UAL2266 - Jul 20, 13:20 UTCJul 20, 14:50 UTC1h 30m
2026-07-17 UAL2472 - Jul 17, 14:20 UTCJul 17, 18:05 UTC3h 45m
2026-07-17 UAL738 IAH → YYC Jul 17, 01:45 UTCJul 17, 05:25 UTC3h 40m
2026-07-16 UAL738 - Jul 16, 21:19 UTCJul 16, 23:25 UTC2h 5m
2026-07-16 UAL738 CVG → IAH Jul 16, 21:14 UTCJul 16, 23:23 UTC2h 9m
2026-07-16 UAL2364 - Jul 16, 17:45 UTCJul 16, 19:40 UTC1h 55m
2026-07-16 UAL697 - Jul 16, 12:30 UTCJul 16, 15:05 UTC2h 35m
2026-07-16 UAL697 DCA → IAH Jul 16, 12:38 UTCJul 16, 15:05 UTC2h 27m
2026-07-15 UAL2296 - Jul 15, 22:20 UTCJul 16, 01:05 UTC2h 45m
2026-07-15 UAL1469 - Jul 15, 18:40 UTCJul 15, 20:40 UTC2h 0m
2026-07-15 UAL2281 - Jul 15, 15:05 UTCJul 15, 16:50 UTC1h 45m
2026-07-15 UAL1085 - Jul 15, 10:50 UTCJul 15, 12:35 UTC1h 45m
2026-07-15 UAL1085 MEX → IAH Jul 15, 11:04 UTCJul 15, 12:32 UTC1h 28m
2026-07-14 UAL1090 - Jul 14, 19:35 UTCJul 14, 21:20 UTC1h 45m
2026-07-14 UAL1090 IAH → MEX Jul 14, 19:37 UTCJul 14, 21:20 UTC1h 43m
2026-07-14 UAL697 - Jul 14, 12:25 UTCJul 14, 15:25 UTC3h 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 N829UA page for operator, model, and routing details .

Mode-S AB540D frequently asked

What is Mode-S code AB540D?
AB540D is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N829UA.
Where is Mode-S AB540D registered?
Mode-S code AB540D 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 AB540D broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:15 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AB540D, octal 52652015, decimal 11,228,173.
What flights does AB540D operate?
Mode-S AB540D has broadcast 20 distinct callsigns, including UAL2218, UAL2467, UAL1778, UAL600, UAL1305.