Apparatus

Try JFK, AAL1290, BAW, or N225AN.

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
Broadcasting now · callsign UAL953 · 39,000 ft
Flights observed
216
Distinct callsigns
20
Country
US
Last broadcast
3h ago

Current position

A2CA5F is currently broadcasting. Map zoomed to live position.

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
UAL980 - 21 2026-06-30
UAL981 - 20 2026-06-30
UAL952 - 17 2026-06-26
UAL983 - 15 2026-07-10
UAL953 - 15 2026-07-14
UAL108 United Airlines 15 2026-06-25
UAL909 - 10 2026-07-13
UAL109 United Airlines 10 2026-06-25
UAL982 - 9 2026-07-10
UAL423 United Airlines 9 2026-04-23
UAL908 - 8 2026-07-13
UAL422 United Airlines 8 2026-04-22
UAL770 - 6 2026-06-23
UAL997 - 5 2026-06-14
UAL991 - 5 2026-07-09
UAL543 United Airlines 5 2026-05-17
UAL996 - 4 2026-06-13
UAL992 - 4 2026-07-08
UAL769 - 4 2026-06-23
UAL202 - 4 2026-07-11

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
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
2026-07-02 UAL3903 - Jul 2, 19:20 UTCJul 2, 21:00 UTC1h 40m
2026-07-02 UAL3903 ORD → IAD Jul 2, 19:35 UTCJul 2, 20:46 UTC1h 11m
2026-07-01 UAL908 - Jul 1, 10:30 UTCJul 1, 11:45 UTC1h 15m
2026-07-01 UAL908 AMS → ORD Jul 1, 10:25 UTCJul 1, 18:38 UTC8h 13m
2026-07-01 UAL909 ORD → AMS Jul 1, 00:15 UTCJul 1, 07:25 UTC7h 10m
2026-06-30 UAL981 DUB → ORD Jun 30, 11:15 UTCJun 30, 18:30 UTC7h 15m
2026-06-30 UAL980 PWK → DUB Jun 30, 02:00 UTCJun 30, 08:40 UTC6h 40m
2026-06-29 UAL908 - Jun 29, 10:44 UTCJun 29, 18:34 UTC7h 50m
2026-06-29 UAL909 ORD → AMS Jun 29, 00:24 UTCJun 29, 07:40 UTC7h 15m
2026-06-28 UAL981 DUB → ORD Jun 28, 11:04 UTCJun 28, 18:14 UTC7h 10m
2026-06-28 UAL980 - Jun 28, 07:29 UTCJun 28, 08:19 UTC50m
2026-06-28 UAL980 - Jun 28, 01:44 UTCJun 28, 03:59 UTC2h 15m
2026-06-27 UAL908 - Jun 27, 10:19 UTCJun 27, 18:09 UTC7h 50m
2026-06-27 UAL909 ORD → AMS Jun 27, 00:20 UTCJun 27, 07:34 UTC7h 15m
2026-06-26 UAL952 MUC → ORD Jun 26, 09:59 UTCJun 26, 18:39 UTC8h 40m
2026-06-26 UAL952 MUC → ORD Jun 26, 09:47 UTCJun 26, 18:22 UTC8h 35m
2026-06-25 UAL108 EWR → EDI Jun 25, 22:04 UTCJun 26, 05:30 UTC7h 25m
2026-06-25 UAL109 EDI → EWR Jun 25, 10:59 UTCJun 25, 19:20 UTC8h 20m
2026-06-25 UAL953 - Jun 25, 01:04 UTCJun 25, 08:45 UTC7h 40m
2026-06-23 UAL770 BCN → ORD Jun 23, 14:44 UTCJun 23, 23:24 UTC8h 40m
2026-06-23 UAL769 - Jun 23, 04:39 UTCJun 23, 12:40 UTC8h 0m
2026-06-22 UAL770 BCN → ORD Jun 22, 15:50 UTCJun 23, 00:39 UTC8h 50m
2026-06-22 UAL770 BCN → ORD Jun 22, 13:46 UTCJun 23, 00:25 UTC10h 39m
2026-06-22 UAL769 - Jun 22, 03:14 UTCJun 22, 11:09 UTC7h 55m
2026-06-21 UAL770 BCN → ORD Jun 21, 13:41 UTCJun 21, 21:58 UTC8h 17m
2026-06-21 UAL770 - Jun 21, 13:20 UTCJun 21, 21:44 UTC8h 25m
2026-06-21 UAL769 ORD → BCN Jun 21, 03:19 UTCJun 21, 11:10 UTC7h 50m

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?
Yes. Mode-S A2CA5F is currently airborne.
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 UAL980, UAL981, UAL952, UAL983, UAL953.