Apparatus

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sensors Mode-S transponder

A20F1A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N23139 · EMBRAER ERJ-145XR · operated by UNITED AIRLINES INC

Hex
A20F1A
Octal
50407432
Decimal
10,620,698
Country
US
Tail
N23139
Type
E45X
Broadcasting now · callsign UCA4989 · 28,000 ft
Flights observed
681
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:45 UTC

Current position

A20F1A is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A20F1A 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
UCA4250 - 10 2026-07-09
UCA4965 - 9 2026-07-12
UCA4372 - 9 2026-07-02
UCA4348 - 9 2026-06-27
UCA4882 - 8 2026-07-10
UCA4831 CommutAir 8 2026-07-18
UCA4321 - 8 2026-07-14
UCA4227 - 8 2026-07-12
UCA4814 CommutAir 7 2026-06-14
UCA4268 - 7 2026-07-02
UCA4226 CommutAir 7 2026-07-23
UCA4977 - 6 2026-07-06
UCA4958 - 6 2026-07-20
UCA4922 - 6 2026-07-17
UCA4901 CommutAir 6 2026-05-18
UCA4897 - 6 2026-07-17
UCA4842 CommutAir 6 2026-06-07
UCA4833 CommutAir 6 2026-06-03
UCA4810 - 6 2026-07-07
UCA4308 - 6 2026-07-06

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UCA4273 IAH → GPT Jul 26, 19:50 UTCJul 26, 20:45 UTC55m
2026-07-26 UCA4245 JAN → IAH Jul 26, 17:20 UTCJul 26, 18:10 UTC50m
2026-07-26 UCA4347 IAH → JAN Jul 26, 15:20 UTCJul 26, 16:00 UTC40m
2026-07-26 UCA4232 MOB → IAH Jul 26, 12:25 UTCJul 26, 13:20 UTC55m
2026-07-26 UCA4919 IAH → TUL Jul 26, 01:50 UTCJul 26, 02:35 UTC45m
2026-07-26 UCA4919 IAH → TUL Jul 26, 01:53 UTCJul 26, 02:34 UTC41m
2026-07-25 UCA4339 IAD → ROA Jul 25, 22:30 UTCJul 25, 23:55 UTC1h 25m
2026-07-25 UCA4275 CRP → IAH Jul 25, 19:35 UTCJul 25, 20:55 UTC1h 20m
2026-07-25 UCA4245 JAN → IAH Jul 25, 17:30 UTCJul 25, 18:20 UTC50m
2026-07-25 UCA4347 IAH → JAN Jul 25, 15:15 UTCJul 25, 16:00 UTC45m
2026-07-25 UCA4264 MLM → IAH Jul 25, 12:35 UTCJul 25, 13:20 UTC45m
2026-07-25 UCA4254 DEN → SHV Jul 25, 01:25 UTCJul 25, 02:10 UTC45m
2026-07-25 UCA4254 DEN → SHV Jul 25, 01:38 UTCJul 25, 02:08 UTC30m
2026-07-24 UCA4353 IAD → PVD Jul 24, 23:20 UTCJul 25, 00:05 UTC45m
2026-07-24 UCA4278 IAD → CHS Jul 24, 21:30 UTCJul 24, 22:15 UTC45m
2026-07-24 UCA4980 BTR → IAH Jul 24, 19:20 UTCJul 24, 20:10 UTC50m
2026-07-24 UCA4980 BTR → IAH Jul 24, 19:13 UTCJul 24, 20:05 UTC52m
2026-07-24 UCA4287 IAH → HRL Jul 24, 17:25 UTCJul 24, 18:10 UTC45m
2026-07-24 UCA4947 BTR → IAH Jul 24, 14:50 UTCJul 24, 15:35 UTC45m
2026-07-24 UCA4260 IAH → LIT Jul 24, 12:40 UTCJul 24, 13:25 UTC45m
2026-07-24 UCA4941 BTR → IAH Jul 24, 10:15 UTCJul 24, 10:30 UTC15m
2026-07-24 UCA4941 BTR → IAH Jul 24, 10:12 UTCJul 24, 11:06 UTC54m
2026-07-24 UCA4254 DEN → SHV Jul 24, 02:15 UTCJul 24, 03:00 UTC45m
2026-07-24 UCA4978 LBB → IAH Jul 24, 00:45 UTCJul 24, 01:15 UTC30m
2026-07-23 UCA4978 LBB → IAH Jul 23, 22:05 UTCJul 23, 23:40 UTC1h 35m
2026-07-23 UCA4280 CMH → IAD Jul 23, 19:40 UTCJul 23, 20:50 UTC1h 10m
2026-07-23 UCA4928 CRP → IAH Jul 23, 17:15 UTCJul 23, 17:55 UTC40m
2026-07-23 UCA4894 IAH → CRP Jul 23, 15:40 UTCJul 23, 16:15 UTC35m
2026-07-23 UCA4894 IAH → CRP Jul 23, 15:27 UTCJul 23, 16:13 UTC46m
2026-07-23 UCA4226 LRD → IAH Jul 23, 13:20 UTCJul 23, 14:15 UTC55m
2026-07-23 UCA4892 IAH → LRD Jul 23, 03:00 UTCJul 23, 03:50 UTC50m
2026-07-22 UCA4339 IAD → ROA Jul 22, 20:35 UTCJul 23, 00:35 UTC4h 0m
2026-07-22 UCA4237 IAH → MFE Jul 22, 19:05 UTCJul 22, 19:45 UTC40m
2026-07-22 UCA4237 IAH → MFE Jul 22, 18:57 UTCJul 22, 19:46 UTC49m
2026-07-22 UCA4336 IAD → PVD Jul 22, 17:25 UTCJul 22, 18:10 UTC45m
2026-07-22 UCA4336 IAD → PVD Jul 22, 17:32 UTCJul 22, 18:07 UTC35m
2026-07-22 UCA4989 MOB → IAH Jul 22, 14:20 UTCJul 22, 15:20 UTC1h 0m
2026-07-21 UCA4295 - Jul 21, 23:30 UTCJul 22, 01:25 UTC1h 55m
2026-07-21 UCA4323 DEN → DRO Jul 21, 02:40 UTCJul 21, 04:10 UTC1h 30m
2026-07-20 UCA4310 IAD → BTV Jul 20, 23:30 UTCJul 21, 00:55 UTC1h 24m
2026-07-20 UCA4327 IAD → SYR Jul 20, 19:25 UTCJul 20, 20:10 UTC45m
2026-07-20 UCA4327 IAD → SYR Jul 20, 19:28 UTCJul 20, 20:22 UTC54m
2026-07-20 UCA4349 IAD → BTV Jul 20, 17:18 UTCJul 20, 18:11 UTC53m
2026-07-20 UCA4958 - Jul 20, 14:35 UTCJul 20, 15:45 UTC1h 10m
2026-07-20 UCA4958 GSP → IAD Jul 20, 14:42 UTCJul 20, 15:44 UTC1h 2m
2026-07-20 UCA4961 - Jul 20, 12:40 UTCJul 20, 13:30 UTC50m
2026-07-20 UCA4954 - Jul 20, 00:35 UTCJul 20, 01:30 UTC55m
2026-07-19 UCA4945 - Jul 19, 22:40 UTCJul 19, 23:20 UTC40m
2026-07-18 UCA4831 IAD → ROA Jul 18, 23:40 UTCJul 19, 00:40 UTC1h 0m
2026-07-18 UCA4240 HSV → IAD Jul 18, 17:45 UTCJul 18, 18:25 UTC40m

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 N23139 page for operator, model, and routing details .

Mode-S A20F1A frequently asked

What is Mode-S code A20F1A?
A20F1A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N23139.
Where is Mode-S A20F1A registered?
Mode-S code A20F1A 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 A20F1A broadcasting right now?
Yes. Mode-S A20F1A is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A20F1A, octal 50407432, decimal 10,620,698.
What flights does A20F1A operate?
Mode-S A20F1A has broadcast 20 distinct callsigns, including UCA4250, UCA4965, UCA4372, UCA4348, UCA4882.