Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A1B5E7

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N20904 · BOEING 787-8 Dreamliner · operated by UNITED AIRLINES INC

Hex
A1B5E7
Octal
50332747
Decimal
10,597,863
Country
US
Tail
N20904
Type
B788
No current signal · last broadcast Jul 26, 17:40 UTC
Flights observed
251
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 17:40 UTC

Last known position

Most recent position reported by Mode-S A1B5E7.

Country allocation

The ICAO 24-bit address A1B5E7 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
UAL109 United Airlines 22 2026-07-25
UAL108 - 20 2026-07-12
UAL953 United Airlines 18 2026-07-24
UAL770 United Airlines 17 2026-07-23
UAL981 United Airlines 16 2026-07-24
UAL952 - 15 2026-07-15
UAL769 United Airlines 13 2026-07-23
UAL908 United Airlines 12 2026-07-20
UAL909 - 11 2026-07-19
UAL997 - 9 2026-06-26
UAL996 - 9 2026-06-25
UAL992 United Airlines 8 2026-07-26
UAL991 United Airlines 8 2026-07-26
UAL980 United Airlines 8 2026-07-24
UAL982 - 7 2026-07-06
UAL345 - 6 2026-06-29
UAL983 - 5 2026-07-06
UAL543 United Airlines 5 2026-05-20
UAL1777 United Airlines 5 2026-05-21
UAL3900 United Airlines 4 2026-05-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL991 BCN → IAD Jul 26, 09:50 UTCJul 26, 17:40 UTC7h 50m
2026-07-26 UAL992 IAD → BCN Jul 26, 00:10 UTCJul 26, 07:20 UTC7h 11m
2026-07-25 UAL109 EDI → EWR Jul 25, 10:50 UTCJul 25, 11:45 UTC55m
2026-07-25 UAL109 EDI → EWR Jul 25, 10:21 UTCJul 25, 18:59 UTC8h 38m
2026-07-25 UAL109 EDI → EWR Jul 25, 10:21 UTCJul 25, 19:12 UTC8h 51m
2026-07-24 UAL953 ORD → MUC Jul 24, 23:40 UTCJul 25, 02:15 UTC2h 35m
2026-07-24 UAL953 ORD → MUC Jul 24, 23:42 UTCJul 25, 07:29 UTC7h 47m
2026-07-24 UAL981 DUB → ORD Jul 24, 10:55 UTCJul 24, 18:15 UTC7h 20m
2026-07-24 UAL980 ORD → DUB Jul 24, 02:25 UTCJul 24, 08:45 UTC6h 20m
2026-07-23 UAL770 IAH → EWR Jul 23, 13:40 UTCJul 23, 22:15 UTC8h 35m
2026-07-23 UAL769 BDL → ORD Jul 23, 03:35 UTCJul 23, 11:25 UTC7h 50m
2026-07-22 UAL770 IAH → EWR Jul 22, 23:10 UTCJul 22, 23:15 UTC5m
2026-07-22 UAL770 IAH → EWR Jul 22, 14:43 UTCJul 22, 22:55 UTC8h 12m
2026-07-22 UAL770 IAH → EWR Jul 22, 14:40 UTCJul 22, 23:15 UTC8h 35m
2026-07-22 UAL769 BDL → ORD Jul 22, 04:10 UTCJul 22, 05:25 UTC1h 15m
2026-07-22 UAL769 BDL → ORD Jul 22, 04:08 UTCJul 22, 12:17 UTC8h 9m
2026-07-21 UAL770 IAH → EWR Jul 21, 15:56 UTCJul 22, 00:02 UTC8h 6m
2026-07-21 UAL770 IAH → EWR Jul 21, 15:40 UTCJul 21, 17:10 UTC1h 30m
2026-07-21 UAL769 BDL → ORD Jul 21, 03:35 UTCJul 21, 11:40 UTC8h 5m
2026-07-20 UAL908 AMS → ORD Jul 20, 18:15 UTCJul 20, 18:20 UTC5m
2026-07-20 UAL908 AMS → ORD Jul 20, 10:10 UTCJul 20, 18:20 UTC8h 10m
2026-07-20 UAL908 AMS → ORD Jul 20, 10:20 UTCJul 20, 17:56 UTC7h 36m
2026-07-19 UAL909 ORD → AMS Jul 19, 23:55 UTCJul 20, 07:10 UTC7h 15m
2026-07-19 UAL908 AMS → ORD Jul 19, 10:20 UTCJul 19, 18:05 UTC7h 45m
2026-07-19 UAL908 AMS → ORD Jul 19, 10:20 UTCJul 19, 17:51 UTC7h 31m
2026-07-19 UAL909 - Jul 19, 00:05 UTCJul 19, 07:20 UTC7h 15m
2026-07-19 UAL909 ORD → AMS Jul 19, 00:12 UTCJul 19, 07:06 UTC6h 54m
2026-07-18 UAL981 DUB → ORD Jul 18, 14:35 UTCJul 18, 21:40 UTC7h 5m
2026-07-18 UAL981 DUB → ORD Jul 18, 14:33 UTCJul 18, 21:27 UTC6h 54m
2026-07-18 UAL980 ORD → DUB Jul 18, 05:45 UTCJul 18, 12:15 UTC6h 30m
2026-07-16 UAL770 - Jul 16, 22:35 UTCJul 16, 22:40 UTC5m
2026-07-16 UAL770 BCN → ORD Jul 16, 14:06 UTCJul 16, 22:18 UTC8h 12m
2026-07-16 UAL770 - Jul 16, 13:49 UTCJul 16, 15:30 UTC1h 40m
2026-07-16 UAL769 - Jul 16, 03:30 UTCJul 16, 11:15 UTC7h 45m
2026-07-15 UAL952 - Jul 15, 10:00 UTCJul 15, 18:30 UTC8h 30m
2026-07-14 UAL953 - Jul 14, 23:35 UTCJul 15, 07:40 UTC8h 5m
2026-07-14 UAL953 ORD → MUC Jul 14, 23:42 UTCJul 15, 07:34 UTC7h 52m
2026-07-14 UAL908 - Jul 14, 10:20 UTCJul 14, 18:10 UTC7h 50m
2026-07-14 UAL909 ORD → AMS Jul 14, 00:27 UTCJul 14, 07:23 UTC6h 56m
2026-07-14 UAL909 - Jul 14, 00:00 UTCJul 14, 07:35 UTC7h 35m
2026-07-13 UAL952 MUC → ORD Jul 13, 09:45 UTCJul 13, 18:25 UTC8h 40m
2026-07-13 UAL952 MUC → ORD Jul 13, 09:47 UTCJul 13, 18:06 UTC8h 19m
2026-07-12 UAL108 IAD → MUC Jul 12, 22:30 UTCJul 13, 06:35 UTC8h 5m
2026-07-12 UAL109 MUC → IAD Jul 12, 10:20 UTCJul 12, 18:35 UTC8h 15m
2026-07-12 UAL953 - Jul 12, 01:15 UTCJul 12, 01:30 UTC15m
2026-07-11 UAL953 ORD → MUC Jul 11, 23:42 UTCJul 12, 07:17 UTC7h 35m
2026-07-11 UAL953 - Jul 11, 23:10 UTCJul 12, 01:10 UTC2h 0m
2026-07-11 UAL908 - Jul 11, 10:20 UTCJul 11, 18:20 UTC8h 0m
2026-07-11 UAL908 AMS → ORD Jul 11, 10:20 UTCJul 11, 18:01 UTC7h 41m
2026-07-11 UAL909 AMS → AMS Jul 11, 07:05 UTCJul 11, 07:10 UTC5m

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 N20904 page for operator, model, and routing details .

Mode-S A1B5E7 frequently asked

What is Mode-S code A1B5E7?
A1B5E7 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N20904.
Where is Mode-S A1B5E7 registered?
Mode-S code A1B5E7 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 A1B5E7 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 17:40 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1B5E7, octal 50332747, decimal 10,597,863.
What flights does A1B5E7 operate?
Mode-S A1B5E7 has broadcast 20 distinct callsigns, including UAL109, UAL108, UAL953, UAL770, UAL981.