Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A2BBF2

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N27539 · operated by UNITED AIRLINES INC

Hex
A2BBF2
Octal
50535762
Decimal
10,664,946
Country
US
Tail
N27539
Type
B39M
No current signal · last broadcast Jul 25, 23:55 UTC
Flights observed
455
Distinct callsigns
20
Country
US
Last broadcast
Jul 25, 23:55 UTC

Last known position

Most recent position reported by Mode-S A2BBF2.

Country allocation

The ICAO 24-bit address A2BBF2 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
UAL1511 United Airlines 7 2026-05-25
UAL1873 United Airlines 6 2026-07-03
UAL1031 - 6 2026-06-29
UAL701 United Airlines 5 2026-05-21
UAL2182 United Airlines 5 2026-07-21
UAL1938 - 5 2026-07-02
UAL2855 United Airlines 4 2026-04-15
UAL2245 United Airlines 4 2026-05-20
UAL2029 United Airlines 4 2026-05-13
UAL2025 - 4 2026-07-17
UAL1882 - 4 2026-07-13
UAL1794 - 4 2026-07-13
UAL1650 United Airlines 4 2026-07-18
UAL1250 United Airlines 4 2026-05-21
UAL1020 United Airlines 4 2026-05-22
UAL8181 United Airlines 3 2026-04-15
UAL639 - 3 2026-07-06
UAL638 United Airlines 3 2026-05-04
UAL619 United Airlines 3 2026-04-14
UAL537 - 3 2026-07-13

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-25 UAL1419 CLE → FLL Jul 25, 11:55 UTCJul 25, 23:45 UTC11h 50m
2026-07-25 UAL339 SAL → EWR Jul 25, 05:15 UTCJul 25, 09:20 UTC4h 5m
2026-07-24 UAL1425 EWR → SAL Jul 24, 22:45 UTCJul 25, 02:40 UTC3h 55m
2026-07-24 UAL1340 FLL → EWR Jul 24, 16:10 UTCJul 24, 19:10 UTC3h 0m
2026-07-24 UAL2438 SYR → IAD Jul 24, 11:25 UTCJul 24, 14:20 UTC2h 55m
2026-07-24 UAL1703 PTY → EWR Jul 24, 04:40 UTCJul 24, 08:45 UTC4h 5m
2026-07-23 UAL1034 IAH → PTY Jul 23, 19:45 UTCJul 23, 22:30 UTC2h 45m
2026-07-23 UAL1034 IAH → PTY Jul 23, 19:44 UTCJul 23, 23:15 UTC3h 31m
2026-07-23 UAL1181 MIA → EWR Jul 23, 15:15 UTCJul 23, 17:45 UTC2h 30m
2026-07-22 UAL2406 LAX → SFO Jul 22, 23:55 UTCJul 23, 02:25 UTC2h 30m
2026-07-22 UAL2086 EWR → ATL Jul 22, 18:55 UTCJul 22, 21:45 UTC2h 50m
2026-07-22 UAL360 DFW → EWR Jul 22, 11:10 UTCJul 22, 16:25 UTC5h 15m
2026-07-22 UAL1032 SAN → EWR Jul 22, 03:20 UTCJul 22, 05:05 UTC1h 45m
2026-07-21 UAL308 ATL → EWR Jul 21, 23:05 UTCJul 22, 01:15 UTC2h 10m
2026-07-21 UAL2182 PDX → SFO Jul 21, 19:25 UTCJul 21, 20:55 UTC1h 30m
2026-07-21 UAL2182 PDX → SFO Jul 21, 19:14 UTCJul 21, 20:57 UTC1h 43m
2026-07-21 UAL2182 PDX → SFO Jul 21, 12:35 UTCJul 21, 14:55 UTC2h 20m
2026-07-20 UAL1181 MIA → EWR Jul 20, 15:25 UTCJul 20, 18:10 UTC2h 45m
2026-07-19 UAL2406 LAX → SFO Jul 19, 23:55 UTCJul 20, 02:35 UTC2h 40m
2026-07-19 UAL2095 - Jul 19, 19:15 UTCJul 19, 22:00 UTC2h 45m
2026-07-19 UAL2095 ORD → LAX Jul 19, 19:13 UTCJul 19, 21:47 UTC2h 34m
2026-07-19 UAL2653 RSW → EWR Jul 19, 16:25 UTCJul 19, 17:50 UTC1h 25m
2026-07-19 UAL1878 AUS → ORD Jul 19, 11:50 UTCJul 19, 14:05 UTC2h 15m
2026-07-19 UAL312T - Jul 19, 01:55 UTCJul 19, 04:10 UTC2h 15m
2026-07-18 UAL1650 AUA → ORD Jul 18, 19:05 UTCJul 19, 00:05 UTC5h 0m
2026-07-18 UAL1650 AUA → ORD Jul 18, 19:16 UTCJul 18, 23:46 UTC4h 30m
2026-07-18 UAL1203 IAD → AUA Jul 18, 13:55 UTCJul 18, 17:55 UTC4h 0m
2026-07-18 UAL1453 SFO → IAD Jul 18, 00:00 UTCJul 18, 04:35 UTC4h 35m
2026-07-17 UAL1453 - Jul 17, 23:55 UTCJul 18, 04:40 UTC4h 46m
2026-07-17 UAL1434 IAD → SFO Jul 17, 16:59 UTCJul 17, 21:55 UTC4h 55m
2026-07-17 UAL2022 - Jul 17, 13:45 UTCJul 17, 14:44 UTC1h 0m
2026-07-17 UAL2022 - Jul 17, 11:25 UTCJul 17, 11:39 UTC15m
2026-07-17 UAL2025 - Jul 17, 00:45 UTCJul 17, 01:05 UTC20m
2026-07-16 UAL2025 IAD → SJU Jul 16, 21:48 UTCJul 17, 01:03 UTC3h 15m
2026-07-16 UAL2025 - Jul 16, 21:50 UTCJul 16, 22:30 UTC40m
2026-07-16 UAL1694 CUN → IAD Jul 16, 16:25 UTCJul 16, 19:14 UTC2h 50m
2026-07-16 UAL1619 - Jul 16, 13:05 UTCJul 16, 14:50 UTC1h 45m
2026-07-16 UAL491 - Jul 16, 08:20 UTCJul 16, 11:15 UTC2h 55m
2026-07-16 UAL2215 - Jul 16, 03:25 UTCJul 16, 06:30 UTC3h 5m
2026-07-15 UAL1645 - Jul 15, 22:50 UTCJul 16, 01:20 UTC2h 30m
2026-07-15 UAL544 - Jul 15, 12:35 UTCJul 15, 14:55 UTC2h 20m
2026-07-14 UAL1019 - Jul 14, 23:35 UTCJul 15, 01:25 UTC1h 50m
2026-07-14 UAL1016 - Jul 14, 19:30 UTCJul 14, 21:15 UTC1h 45m
2026-07-14 UAL1823 - Jul 14, 14:50 UTCJul 14, 16:00 UTC1h 10m
2026-07-14 UAL1823 PNS → IAH Jul 14, 14:12 UTCJul 14, 16:07 UTC1h 55m
2026-07-14 UAL497 - Jul 14, 03:20 UTCJul 14, 04:25 UTC1h 5m
2026-07-14 UAL497 SLC → IAH Jul 14, 03:28 UTCJul 14, 04:23 UTC55m
2026-07-13 UAL2078 - Jul 13, 22:25 UTCJul 14, 01:55 UTC3h 30m
2026-07-13 UAL1882 - Jul 13, 15:25 UTCJul 13, 18:40 UTC3h 15m
2026-07-13 UAL537 - Jul 13, 12:10 UTCJul 13, 13:45 UTC1h 35m

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 N27539 page for operator, model, and routing details .

Mode-S A2BBF2 frequently asked

What is Mode-S code A2BBF2?
A2BBF2 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N27539.
Where is Mode-S A2BBF2 registered?
Mode-S code A2BBF2 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 A2BBF2 broadcasting right now?
No active broadcast right now. Last signal was Jul 25, 23:55 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A2BBF2, octal 50535762, decimal 10,664,946.
What flights does A2BBF2 operate?
Mode-S A2BBF2 has broadcast 20 distinct callsigns, including UAL1511, UAL1873, UAL1031, UAL701, UAL2182.