Apparatus

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sensors Mode-S transponder

A2CA5D

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N27901 · BOEING 787-8 Dreamliner · operated by UNITED AIRLINES INC

Hex
A2CA5D
Octal
50545135
Decimal
10,668,637
Country
US
Tail
N27901
Type
B788
Broadcasting now · callsign UAL983 · 38,000 ft
Flights observed
196
Distinct callsigns
20
Country
US
Last broadcast
1h ago

Current position

A2CA5D is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A2CA5D 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
UAL613 - 19 2026-06-30
UAL612 - 18 2026-07-01
UAL981 United Airlines 15 2026-06-13
UAL952 - 13 2026-06-25
UAL996 - 12 2026-07-09
UAL980 - 10 2026-06-13
UAL953 - 10 2026-06-25
UAL1147 United Airlines 10 2026-06-09
UAL997 - 9 2026-07-10
UAL982 - 9 2026-07-13
UAL2274 United Airlines 8 2026-06-09
UAL108 United Airlines 8 2026-07-02
UAL983 - 7 2026-07-14
UAL422 United Airlines 7 2026-04-18
UAL991 - 6 2026-07-13
UAL992 - 5 2026-07-12
UAL423 United Airlines 5 2026-04-19
UAL109 United Airlines 5 2026-07-03
UAL344 - 4 2026-07-12
UAL909 United Airlines 3 2026-06-14

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 UAL983 - Jul 14, 09:05 UTCJul 14, 11:15 UTC2h 10m
2026-07-13 UAL982 IAD → ATH Jul 13, 21:58 UTCJul 14, 07:03 UTC9h 5m
2026-07-13 UAL982 IAD → ATH Jul 13, 22:00 UTCJul 14, 07:10 UTC9h 10m
2026-07-13 UAL991 - Jul 13, 09:30 UTCJul 13, 11:05 UTC1h 35m
2026-07-13 UAL991 BCN → IAD Jul 13, 09:37 UTCJul 13, 17:32 UTC7h 55m
2026-07-12 UAL992 IAD → BCN Jul 12, 22:56 UTCJul 13, 06:19 UTC7h 23m
2026-07-12 UAL992 IAD → BCN Jul 12, 22:55 UTCJul 13, 06:20 UTC7h 25m
2026-07-12 UAL344 - Jul 12, 05:45 UTCJul 12, 10:25 UTC4h 40m
2026-07-12 UAL344 - Jul 12, 01:50 UTCJul 12, 02:05 UTC15m
2026-07-11 UAL345 - Jul 11, 12:45 UTCJul 11, 21:55 UTC9h 10m
2026-07-11 UAL344 - Jul 11, 05:20 UTCJul 11, 09:55 UTC4h 35m
2026-07-11 UAL344 - Jul 11, 01:40 UTCJul 11, 01:55 UTC15m
2026-07-10 UAL345 - Jul 10, 22:15 UTCJul 10, 22:35 UTC20m
2026-07-10 UAL345 - Jul 10, 13:00 UTCJul 10, 18:20 UTC5h 20m
2026-07-10 UAL997 - Jul 10, 00:20 UTCJul 10, 08:15 UTC7h 55m
2026-07-09 UAL996 - Jul 9, 05:45 UTCJul 10, 01:15 UTC19h 30m
2026-07-08 UAL996 IAD → ACC Jul 8, 23:21 UTCJul 9, 08:54 UTC9h 33m
2026-07-08 UAL996 - Jul 8, 23:05 UTCJul 9, 06:50 UTC7h 45m
2026-07-07 UAL983 ATH → IAD Jul 7, 10:15 UTCJul 7, 20:00 UTC9h 45m
2026-07-06 UAL982 IAD → ATH Jul 6, 23:10 UTCJul 7, 07:55 UTC8h 45m
2026-07-04 UAL983 ATH → IAD Jul 4, 09:15 UTCJul 4, 19:35 UTC10h 20m
2026-07-03 UAL982 IAD → ATH Jul 3, 22:23 UTCJul 4, 07:14 UTC8h 51m
2026-07-03 UAL982 IAD → ATH Jul 3, 22:25 UTCJul 4, 07:20 UTC8h 55m
2026-07-03 UAL109 EDI → EWR Jul 3, 10:15 UTCJul 3, 19:00 UTC8h 45m
2026-07-02 UAL108 EWR → EDI Jul 2, 22:40 UTCJul 3, 05:45 UTC7h 5m
2026-07-02 UAL108 EWR → EDI Jul 2, 22:18 UTCJul 3, 05:43 UTC7h 25m
2026-07-01 UAL3868 IAD → IAD Jul 1, 23:15 UTCJul 2, 00:00 UTC45m
2026-07-01 UAL612 IAD → IAD Jul 1, 04:45 UTCJul 1, 06:10 UTC1h 25m
2026-07-01 UAL612 IAD → IAD Jul 1, 04:38 UTCJul 1, 14:46 UTC10h 8m
2026-06-30 UAL613 - Jun 30, 08:00 UTCJun 30, 09:30 UTC1h 30m
2026-06-29 UAL613 LOS → IAD Jun 29, 23:15 UTCJun 30, 09:33 UTC10h 18m
2026-06-29 UAL613 - Jun 29, 09:50 UTCJun 30, 02:15 UTC16h 26m
2026-06-29 UAL612 IAD → LOS Jun 29, 03:03 UTCJun 29, 13:12 UTC10h 9m
2026-06-29 UAL612 - Jun 29, 03:10 UTCJun 30, 01:09 UTC22h 0m
2026-06-28 UAL3929 MUC → IAD Jun 28, 12:35 UTCJun 28, 20:54 UTC8h 20m
2026-06-25 UAL953 ORD → MUC Jun 25, 23:30 UTCJun 26, 07:14 UTC7h 45m
2026-06-25 UAL952 MUC → ORD Jun 25, 09:55 UTCJun 25, 18:34 UTC8h 40m
2026-06-24 UAL108 EWR → EDI Jun 24, 21:54 UTCJun 25, 05:29 UTC7h 35m
2026-06-24 UAL991 - Jun 24, 09:29 UTCJun 24, 11:05 UTC1h 35m
2026-06-24 UAL991 BCN → IAD Jun 24, 09:37 UTCJun 24, 17:49 UTC8h 12m
2026-06-24 UAL991 BCN → IAD Jun 24, 09:37 UTCJun 24, 17:48 UTC8h 11m
2026-06-23 UAL992 IAD → BCN Jun 23, 23:00 UTCJun 24, 06:04 UTC7h 5m
2026-06-22 UAL613 - Jun 22, 09:14 UTCJun 22, 10:05 UTC50m
2026-06-21 UAL613 - Jun 21, 11:40 UTCJun 22, 10:05 UTC22h 25m
2026-06-21 UAL612 - Jun 21, 05:15 UTCJun 21, 12:40 UTC7h 25m
2026-06-20 UAL613 - Jun 20, 01:39 UTCJun 20, 09:49 UTC8h 10m
2026-06-19 UAL612 - Jun 19, 10:04 UTCJun 20, 09:14 UTC23h 10m
2026-06-19 UAL612 - Jun 19, 03:34 UTCJun 19, 11:09 UTC7h 35m
2026-06-19 UAL612 IAD → LOS Jun 19, 03:28 UTCJun 19, 13:19 UTC9h 51m
2026-06-18 UAL991 BCN → IAD Jun 18, 09:45 UTCJun 18, 17:50 UTC8h 5m

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 N27901 page for operator, model, and routing details .

Mode-S A2CA5D frequently asked

What is Mode-S code A2CA5D?
A2CA5D is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N27901.
Where is Mode-S A2CA5D registered?
Mode-S code A2CA5D 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 A2CA5D broadcasting right now?
Yes. Mode-S A2CA5D is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A2CA5D, octal 50545135, decimal 10,668,637.
What flights does A2CA5D operate?
Mode-S A2CA5D has broadcast 20 distinct callsigns, including UAL613, UAL612, UAL981, UAL952, UAL996.