Apparatus

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sensors Mode-S transponder

A2CA5F

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N27903 · BOEING 787-8 Dreamliner · operated by UNITED AIRLINES INC

Hex
A2CA5F
Octal
50545137
Decimal
10,668,639
Country
US
Tail
N27903
Type
B788
No current signal · last broadcast Jul 26, 09:20 UTC
Flights observed
243
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 09:20 UTC

Last known position

Most recent position reported by Mode-S A2CA5F.

Country allocation

The ICAO 24-bit address A2CA5F 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
UAL983 United Airlines 21 2026-07-21
UAL980 - 21 2026-06-30
UAL981 - 20 2026-06-30
UAL952 United Airlines 18 2026-07-23
UAL108 United Airlines 16 2026-07-22
UAL953 - 15 2026-07-14
UAL982 United Airlines 12 2026-07-20
UAL909 United Airlines 11 2026-07-24
UAL109 - 11 2026-07-14
UAL908 United Airlines 9 2026-07-24
UAL423 United Airlines 9 2026-04-23
UAL422 United Airlines 8 2026-04-22
UAL997 United Airlines 6 2026-07-19
UAL996 - 6 2026-07-17
UAL992 - 6 2026-07-21
UAL991 United Airlines 6 2026-07-22
UAL770 - 6 2026-06-23
UAL202 United Airlines 6 2026-07-25
UAL543 United Airlines 5 2026-05-17
UAL344 - 5 2026-07-20

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL203 SFO → ABQ Jul 26, 05:20 UTCJul 26, 09:20 UTC4h 1m
2026-07-25 UAL202 PWM → ORD Jul 25, 22:55 UTCJul 25, 23:05 UTC10m
2026-07-25 UAL202 PWM → ORD Jul 25, 15:00 UTCJul 25, 18:40 UTC3h 40m
2026-07-24 UAL908 AMS → ORD Jul 24, 11:45 UTCJul 24, 19:50 UTC8h 5m
2026-07-24 UAL909 ORD → AMS Jul 24, 00:20 UTCJul 24, 07:15 UTC6h 55m
2026-07-23 UAL952 MUC → ORD Jul 23, 09:45 UTCJul 23, 18:45 UTC9h 0m
2026-07-22 UAL108 EWR → EDI Jul 22, 22:25 UTCJul 23, 05:55 UTC7h 30m
2026-07-22 UAL991 BCN → IAD Jul 22, 10:20 UTCJul 22, 17:30 UTC7h 10m
2026-07-21 UAL992 IAD → BCN Jul 21, 23:36 UTCJul 22, 07:23 UTC7h 47m
2026-07-21 UAL992 - Jul 21, 23:50 UTCJul 22, 00:45 UTC55m
2026-07-21 UAL983 ATH → IAD Jul 21, 19:45 UTCJul 21, 20:00 UTC15m
2026-07-21 UAL983 ATH → IAD Jul 21, 09:25 UTCJul 21, 19:29 UTC10h 4m
2026-07-21 UAL983 ATH → IAD Jul 21, 09:20 UTCJul 21, 13:05 UTC3h 45m
2026-07-20 UAL982 IAD → ATH Jul 20, 22:20 UTCJul 21, 07:20 UTC8h 59m
2026-07-20 UAL344 - Jul 20, 05:30 UTCJul 20, 09:45 UTC4h 15m
2026-07-20 UAL344 - Jul 20, 01:35 UTCJul 20, 01:50 UTC15m
2026-07-20 UAL344 HNL → IAD Jul 20, 01:44 UTCJul 20, 09:48 UTC8h 4m
2026-07-19 UAL345 - Jul 19, 12:55 UTCJul 19, 22:15 UTC9h 20m
2026-07-19 UAL997 ACC → IAD Jul 19, 08:00 UTCJul 19, 08:50 UTC50m
2026-07-17 UAL996 - Jul 17, 23:00 UTCJul 17, 23:45 UTC45m
2026-07-17 UAL996 IAD → ACC Jul 17, 23:06 UTCJul 18, 08:50 UTC9h 44m
2026-07-17 UAL983 - Jul 17, 10:25 UTCJul 17, 13:45 UTC3h 20m
2026-07-17 UAL983 ATH → IAD Jul 17, 09:55 UTCJul 17, 20:21 UTC10h 26m
2026-07-16 UAL982 IAD → ATH Jul 16, 23:15 UTCJul 17, 08:04 UTC8h 50m
2026-07-15 UAL983 ATH → IAD Jul 15, 13:15 UTCJul 15, 23:25 UTC10h 10m
2026-07-15 UAL982 IAD → ATH Jul 15, 01:50 UTCJul 15, 10:50 UTC9h 0m
2026-07-14 UAL109 - Jul 14, 11:20 UTCJul 14, 19:20 UTC8h 0m
2026-07-14 UAL953 ORD → MUC Jul 14, 01:27 UTCJul 14, 09:19 UTC7h 52m
2026-07-14 UAL953 - Jul 14, 00:55 UTCJul 14, 01:10 UTC15m
2026-07-13 UAL908 - Jul 13, 10:20 UTCJul 13, 18:10 UTC7h 50m
2026-07-13 UAL909 ORD → AMS Jul 13, 00:12 UTCJul 13, 07:19 UTC7h 7m
2026-07-13 UAL909 ORD → AMS Jul 13, 00:01 UTCJul 13, 07:30 UTC7h 30m
2026-07-12 UAL203 OGG → ORD Jul 12, 02:16 UTCJul 12, 09:51 UTC7h 35m
2026-07-11 UAL202 - Jul 11, 14:45 UTCJul 11, 18:45 UTC4h 0m
2026-07-11 UAL3932 IAD → ORD Jul 11, 03:30 UTCJul 11, 04:55 UTC1h 25m
2026-07-10 UAL983 ATH → IAD Jul 10, 13:05 UTCJul 10, 23:45 UTC10h 40m
2026-07-10 UAL982 IAD → ATH Jul 10, 01:10 UTCJul 10, 10:20 UTC9h 10m
2026-07-09 UAL991 BCN → IAD Jul 9, 09:35 UTCJul 9, 17:45 UTC8h 10m
2026-07-08 UAL992 IAD → BCN Jul 8, 23:20 UTCJul 9, 06:45 UTC7h 25m
2026-07-08 UAL983 ATH → IAD Jul 8, 09:55 UTCJul 8, 19:55 UTC10h 0m
2026-07-07 UAL982 IAD → ATH Jul 7, 22:10 UTCJul 8, 07:10 UTC9h 0m
2026-07-07 UAL344 - Jul 7, 05:50 UTCJul 7, 10:30 UTC4h 40m
2026-07-07 UAL344 - Jul 7, 02:15 UTCJul 7, 02:30 UTC15m
2026-07-06 UAL345 - Jul 6, 23:50 UTCJul 7, 00:10 UTC20m
2026-07-06 UAL345 - Jul 6, 15:35 UTCJul 6, 20:10 UTC4h 35m
2026-07-04 UAL613 - Jul 4, 02:20 UTCJul 4, 09:55 UTC7h 35m
2026-07-03 UAL613 - Jul 3, 10:20 UTCJul 4, 09:45 UTC23h 25m
2026-07-03 UAL612 - Jul 3, 03:50 UTCJul 4, 02:45 UTC22h 55m
2026-07-03 UAL612 - Jul 3, 03:35 UTCJul 3, 04:25 UTC50m
2026-07-03 UAL612 IAD → LOS Jul 3, 02:59 UTCJul 3, 13:42 UTC10h 43m

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 N27903 page for operator, model, and routing details .

Mode-S A2CA5F frequently asked

What is Mode-S code A2CA5F?
A2CA5F is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N27903.
Where is Mode-S A2CA5F registered?
Mode-S code A2CA5F 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 A2CA5F broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 09:20 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A2CA5F, octal 50545137, decimal 10,668,639.
What flights does A2CA5F operate?
Mode-S A2CA5F has broadcast 20 distinct callsigns, including UAL983, UAL980, UAL981, UAL952, UAL108.