Apparatus

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sensors Mode-S transponder

A53B2B

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N436UA · AIRBUS A-320 · operated by UNITED AIRLINES INC

Hex
A53B2B
Octal
51235453
Decimal
10,828,587
Country
US
Tail
N436UA
Type
A320
Broadcasting now · callsign UAL561 · 28,075 ft
Flights observed
410
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:45 UTC

Current position

A53B2B is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A53B2B 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
UAL215 United Airlines 6 2026-06-01
UAL2447 - 5 2026-07-11
UAL2329 United Airlines 5 2026-06-13
UAL2218 United Airlines 5 2026-06-02
UAL1003 - 5 2026-06-17
UAL2832 United Airlines 4 2026-06-01
UAL247 United Airlines 4 2026-07-23
UAL2315 United Airlines 4 2026-05-28
UAL1778 - 4 2026-07-10
UAL1633 - 4 2026-06-16
UAL1337 United Airlines 4 2026-07-18
UAL1061 United Airlines 4 2026-07-24
UAL626 - 3 2026-06-30
UAL600 - 3 2026-07-10
UAL576 United Airlines 3 2026-06-04
UAL357 - 3 2026-06-30
UAL2334 - 3 2026-07-13
UAL2193 - 3 2026-07-17
UAL1936 United Airlines 3 2026-04-18
UAL1878 United Airlines 3 2026-05-28

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL720 PHL → DEN Jul 26, 21:45 UTCJul 26, 22:45 UTC1h 0m
2026-07-26 UAL2787 GUM → SFO Jul 26, 17:15 UTCJul 26, 19:30 UTC2h 15m
2026-07-26 UAL2838 HKG → SFO Jul 26, 14:10 UTCJul 26, 15:25 UTC1h 15m
2026-07-26 UAL1436 BOS → ORD Jul 26, 00:30 UTCJul 26, 01:30 UTC1h 0m
2026-07-25 UAL1762 SDF → DEN Jul 25, 19:35 UTCJul 25, 22:45 UTC3h 10m
2026-07-25 UAL1762 SDF → DEN Jul 25, 19:35 UTCJul 25, 22:39 UTC3h 4m
2026-07-25 UAL2427 ORD → SXM Jul 25, 16:00 UTCJul 25, 17:50 UTC1h 50m
2026-07-25 UAL1338 LGA → ORD Jul 25, 13:05 UTCJul 25, 13:50 UTC45m
2026-07-25 UAL2426 IAH → BOS Jul 25, 01:10 UTCJul 25, 01:55 UTC45m
2026-07-24 UAL1625 EWR → DEN Jul 24, 20:50 UTCJul 24, 23:15 UTC2h 25m
2026-07-24 UAL1061 SEA → SFO Jul 24, 17:25 UTCJul 24, 19:30 UTC2h 5m
2026-07-24 UAL1061 SEA → SFO Jul 24, 17:16 UTCJul 24, 19:26 UTC2h 10m
2026-07-24 UAL2774 NRT → SFO Jul 24, 13:40 UTCJul 24, 15:10 UTC1h 30m
2026-07-24 UAL2774 NRT → SFO Jul 24, 13:42 UTCJul 24, 14:55 UTC1h 13m
2026-07-23 UAL1369 IAH → EWR Jul 23, 23:35 UTCJul 24, 00:55 UTC1h 20m
2026-07-23 UAL739 SFO → AUS Jul 23, 20:30 UTCJul 23, 21:35 UTC1h 5m
2026-07-23 UAL247 DTW → ORD Jul 23, 17:55 UTCJul 23, 18:55 UTC1h 0m
2026-07-23 UAL247 DTW → ORD Jul 23, 18:09 UTCJul 23, 18:53 UTC44m
2026-07-23 UAL1660 ANC → EWR Jul 23, 16:00 UTCJul 23, 16:25 UTC25m
2026-07-23 UAL2093 - Jul 23, 14:05 UTCJul 23, 14:30 UTC25m
2026-07-23 UAL2093 ORD → MSN Jul 23, 14:10 UTCJul 23, 14:28 UTC18m
2026-07-23 UAL1744 IAD → ORD Jul 23, 00:35 UTCJul 23, 02:20 UTC1h 45m
2026-07-22 UAL623 LGA → ORD Jul 22, 18:15 UTCJul 22, 20:45 UTC2h 30m
2026-07-22 UAL704 IAH → EWR Jul 22, 14:50 UTCJul 22, 16:40 UTC1h 50m
2026-07-22 UAL1269 LGA → IAH Jul 22, 11:50 UTCJul 22, 13:10 UTC1h 20m
2026-07-22 UAL1084 - Jul 22, 01:20 UTCJul 22, 01:25 UTC5m
2026-07-21 UAL1084 CLE → ORD Jul 21, 23:55 UTCJul 22, 01:25 UTC1h 30m
2026-07-21 UAL1084 LAX → CLE Jul 21, 23:51 UTCJul 22, 01:05 UTC1h 14m
2026-07-21 UAL1934 LAS → DEN Jul 21, 19:55 UTCJul 21, 22:20 UTC2h 25m
2026-07-21 UAL1747 TPA → EWR Jul 21, 17:32 UTCJul 21, 18:15 UTC43m
2026-07-21 UAL1747 TPA → EWR Jul 21, 17:30 UTCJul 21, 18:05 UTC35m
2026-07-21 UAL1823 SFO → DEN Jul 21, 15:30 UTCJul 21, 15:55 UTC25m
2026-07-21 UAL1345 MIA → EWR Jul 21, 11:05 UTCJul 21, 13:55 UTC2h 50m
2026-07-20 UAL313 BOI → SFO Jul 20, 23:45 UTCJul 21, 02:30 UTC2h 45m
2026-07-20 UAL2682 EWR → RDU Jul 20, 21:35 UTCJul 20, 22:15 UTC40m
2026-07-20 UAL2682 EWR → RDU Jul 20, 21:24 UTCJul 20, 22:13 UTC49m
2026-07-20 UAL1564 IAD → DFW Jul 20, 17:30 UTCJul 20, 20:10 UTC2h 40m
2026-07-20 UAL1535 - Jul 20, 15:15 UTCJul 20, 15:55 UTC40m
2026-07-20 UAL529 IAD → RDU Jul 20, 12:50 UTCJul 20, 13:30 UTC40m
2026-07-20 UAL1524 IAH → EWR Jul 20, 10:20 UTCJul 20, 10:55 UTC35m
2026-07-20 UAL8132 IAD → ORF Jul 20, 03:50 UTCJul 20, 04:25 UTC35m
2026-07-20 UAL8132 IAD → ORF Jul 20, 03:55 UTCJul 20, 04:19 UTC24m
2026-07-20 UAL2634 ATL → IAD Jul 20, 01:05 UTCJul 20, 02:25 UTC1h 20m
2026-07-19 UAL1671 DEN → ATL Jul 19, 19:55 UTCJul 19, 22:45 UTC2h 50m
2026-07-19 UAL2375 PDX → DEN Jul 19, 16:00 UTCJul 19, 18:05 UTC2h 5m
2026-07-18 UAL1337 EWR → PDX Jul 18, 23:21 UTCJul 19, 01:24 UTC2h 3m
2026-07-18 UAL1337 EWR → PDX Jul 18, 23:10 UTCJul 19, 00:45 UTC1h 35m
2026-07-18 UAL1380 STL → DEN Jul 18, 19:55 UTCJul 18, 21:35 UTC1h 40m
2026-07-18 UAL652 DEN → STL Jul 18, 17:05 UTCJul 18, 18:45 UTC1h 40m
2026-07-17 UAL2200 DEN → DEN Jul 17, 22:40 UTCJul 18, 15:35 UTC16h 56m

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 N436UA page for operator, model, and routing details .

Mode-S A53B2B frequently asked

What is Mode-S code A53B2B?
A53B2B is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N436UA.
Where is Mode-S A53B2B registered?
Mode-S code A53B2B 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 A53B2B broadcasting right now?
Yes. Mode-S A53B2B is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A53B2B, octal 51235453, decimal 10,828,587.
What flights does A53B2B operate?
Mode-S A53B2B has broadcast 20 distinct callsigns, including UAL215, UAL2447, UAL2329, UAL2218, UAL1003.