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
No current signal · last broadcast Jul 26, 21:15 UTC
Flights observed
221
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:15 UTC

Last known position

Most recent position reported by Mode-S A2CA5D.

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 United Airlines 14 2026-07-21
UAL996 - 13 2026-07-15
UAL997 - 11 2026-07-17
UAL992 - 10 2026-07-19
UAL980 - 10 2026-06-13
UAL953 - 10 2026-06-25
UAL1147 United Airlines 10 2026-06-09
UAL991 United Airlines 9 2026-07-20
UAL982 - 9 2026-07-13
UAL108 - 9 2026-07-20
UAL2274 United Airlines 8 2026-06-09
UAL983 - 7 2026-07-14
UAL422 United Airlines 7 2026-04-18
UAL908 United Airlines 6 2026-07-23
UAL423 United Airlines 5 2026-04-19
UAL345 - 5 2026-07-17
UAL344 - 5 2026-07-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL770 IAH → EWR Jul 26, 13:35 UTCJul 26, 21:15 UTC7h 40m
2026-07-26 UAL769 BDL → ORD Jul 26, 03:20 UTCJul 26, 11:15 UTC7h 56m
2026-07-25 UAL770 IAH → EWR Jul 25, 13:30 UTCJul 25, 22:10 UTC8h 40m
2026-07-25 UAL769 BDL → ORD Jul 25, 03:13 UTCJul 25, 11:13 UTC8h 0m
2026-07-25 UAL769 BDL → ORD Jul 25, 03:20 UTCJul 25, 11:25 UTC8h 5m
2026-07-23 UAL908 AMS → ORD Jul 23, 10:30 UTCJul 23, 18:35 UTC8h 5m
2026-07-23 UAL909 ORD → AMS Jul 23, 00:10 UTCJul 23, 07:35 UTC7h 25m
2026-07-22 UAL908 AMS → ORD Jul 22, 10:30 UTCJul 22, 18:27 UTC7h 57m
2026-07-22 UAL908 AMS → ORD Jul 22, 00:00 UTCJul 22, 18:40 UTC18h 40m
2026-07-21 UAL952 MUC → ORD Jul 21, 09:50 UTCJul 21, 18:55 UTC9h 5m
2026-07-20 UAL108 IAD → MUC Jul 20, 21:45 UTCJul 21, 05:35 UTC7h 49m
2026-07-20 UAL991 BCN → IAD Jul 20, 09:35 UTCJul 20, 17:55 UTC8h 20m
2026-07-19 UAL992 IAD → BCN Jul 19, 23:20 UTCJul 20, 06:35 UTC7h 15m
2026-07-19 UAL991 BCN → IAD Jul 19, 10:45 UTCJul 19, 18:40 UTC7h 55m
2026-07-19 UAL992 IAD → BCN Jul 19, 00:56 UTCJul 19, 08:47 UTC7h 51m
2026-07-19 UAL992 IAD → BCN Jul 19, 01:10 UTCJul 19, 08:50 UTC7h 40m
2026-07-18 UAL344 - Jul 18, 01:39 UTCJul 18, 10:00 UTC8h 21m
2026-07-17 UAL345 - Jul 17, 12:55 UTCJul 17, 22:10 UTC9h 15m
2026-07-17 UAL345 IAD → HNL Jul 17, 12:50 UTCJul 17, 22:08 UTC9h 18m
2026-07-17 UAL997 - Jul 17, 01:05 UTCJul 17, 08:59 UTC7h 55m
2026-07-16 UAL997 ACC → IAD Jul 16, 22:38 UTCJul 17, 08:55 UTC10h 17m
2026-07-15 UAL996 - Jul 15, 23:40 UTCJul 16, 07:15 UTC7h 35m
2026-07-15 UAL991 BCN → IAD Jul 15, 09:35 UTCJul 15, 17:55 UTC8h 20m
2026-07-14 UAL992 IAD → BCN Jul 14, 23:05 UTCJul 15, 06:25 UTC7h 20m
2026-07-14 UAL992 IAD → BCN Jul 14, 23:05 UTCJul 15, 06:20 UTC7h 15m
2026-07-14 UAL983 ATH → IAD Jul 14, 09:05 UTCJul 14, 19:10 UTC10h 5m
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

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?
No active broadcast right now. Last signal was Jul 26, 21:15 UTC.
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.