Apparatus

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sensors Mode-S transponder

A2B157

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N27277 · BOEING 737 MAX 8 · operated by UNITED AIRLINES INC

Hex
A2B157
Octal
50530527
Decimal
10,662,231
Country
US
Tail
N27277
Type
B38M
No current signal · last broadcast Jul 26, 21:35 UTC
Flights observed
429
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:35 UTC

Last known position

Most recent position reported by Mode-S A2B157.

Country allocation

The ICAO 24-bit address A2B157 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
UAL2859 United Airlines 7 2026-07-24
UAL1699 - 7 2026-06-27
UAL368 United Airlines 6 2026-07-21
UAL2409 - 6 2026-07-08
UAL1678 - 6 2026-07-20
UAL1584 - 6 2026-07-24
UAL1530 United Airlines 6 2026-05-07
UAL2459 - 5 2026-07-18
UAL1443 United Airlines 5 2026-07-25
UAL278 United Airlines 4 2026-04-14
UAL1968 United Airlines 4 2026-04-21
UAL1716 - 4 2026-06-30
UAL1698 United Airlines 4 2026-07-23
UAL1306 - 4 2026-06-29
UAL1219 United Airlines 4 2026-05-30
UAL598 United Airlines 3 2026-06-13
UAL494 United Airlines 3 2026-05-25
UAL280 United Airlines 3 2026-06-12
UAL2748 - 3 2026-06-20
UAL2478 United Airlines 3 2026-04-20

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1840 EWR → ORD Jul 26, 20:15 UTCJul 26, 21:35 UTC1h 20m
2026-07-26 UAL1537 RSW → EWR Jul 26, 14:10 UTCJul 26, 17:45 UTC3h 35m
2026-07-26 UAL1776 LAX → SFO Jul 26, 00:10 UTCJul 26, 01:45 UTC1h 35m
2026-07-25 UAL2365 SJC → ORD Jul 25, 18:15 UTCJul 25, 22:35 UTC4h 20m
2026-07-25 UAL1443 IAD → STT Jul 25, 12:55 UTCJul 25, 16:35 UTC3h 40m
2026-07-25 UAL1366 IAD → DEN Jul 25, 10:30 UTCJul 25, 11:10 UTC40m
2026-07-24 UAL2036 SJU → EWR Jul 24, 23:10 UTCJul 25, 02:50 UTC3h 40m
2026-07-24 UAL1339 LAX → DEN Jul 24, 21:25 UTCJul 24, 21:45 UTC20m
2026-07-24 UAL1339 LAX → DEN Jul 24, 16:20 UTCJul 24, 19:45 UTC3h 25m
2026-07-24 UAL1584 - Jul 24, 13:35 UTCJul 24, 14:00 UTC25m
2026-07-24 UAL2859 ORD → CVG Jul 24, 02:40 UTCJul 24, 02:55 UTC15m
2026-07-24 UAL2859 ORD → CVG Jul 24, 02:20 UTCJul 24, 02:57 UTC37m
2026-07-23 UAL1698 SFO → SLC Jul 23, 12:40 UTCJul 23, 22:50 UTC10h 10m
2026-07-22 UAL1446 LIR → EWR Jul 22, 22:50 UTCJul 23, 03:05 UTC4h 15m
2026-07-22 UAL1917 DEN → LIR Jul 22, 16:29 UTCJul 22, 21:00 UTC4h 31m
2026-07-22 UAL1917 DEN → LIR Jul 22, 16:15 UTCJul 22, 18:35 UTC2h 20m
2026-07-22 UAL1607 IND → DEN Jul 22, 12:15 UTCJul 22, 14:30 UTC2h 15m
2026-07-21 UAL1902 - Jul 21, 18:55 UTCJul 21, 22:40 UTC3h 45m
2026-07-21 UAL1596 PDX → SFO Jul 21, 15:55 UTCJul 21, 17:20 UTC1h 25m
2026-07-21 UAL2384 ORD → SFO Jul 21, 06:35 UTCJul 21, 07:50 UTC1h 15m
2026-07-21 UAL368 EWR → FLL Jul 21, 00:05 UTCJul 21, 05:10 UTC5h 5m
2026-07-20 UAL1678 SFO → DCA Jul 20, 15:50 UTCJul 20, 20:40 UTC4h 50m
2026-07-20 UAL1125 - Jul 20, 12:55 UTCJul 20, 13:35 UTC40m
2026-07-20 UAL1749 SFO → OGG Jul 20, 01:50 UTCJul 20, 02:40 UTC50m
2026-07-19 UAL8196 STL → YYZ Jul 19, 22:55 UTCJul 20, 00:40 UTC1h 45m
2026-07-19 UAL780T - Jul 19, 16:35 UTCJul 19, 21:30 UTC4h 55m
2026-07-18 UAL2275 YYC → IAD Jul 18, 21:25 UTCJul 19, 01:10 UTC3h 45m
2026-07-18 UAL2459 DEN → YYC Jul 18, 17:50 UTCJul 18, 19:55 UTC2h 5m
2026-07-18 UAL2853 - Jul 18, 14:00 UTCJul 18, 15:45 UTC1h 45m
2026-07-18 UAL1394 IAH → PIT Jul 18, 04:05 UTCJul 18, 06:15 UTC2h 10m
2026-07-17 UAL1182 - Jul 17, 23:25 UTCJul 18, 02:00 UTC2h 35m
2026-07-17 UAL1598 - Jul 17, 16:10 UTCJul 17, 19:40 UTC3h 30m
2026-07-17 UAL1598 DEN → PWM Jul 17, 16:15 UTCJul 17, 19:43 UTC3h 28m
2026-07-17 UAL1607 - Jul 17, 12:25 UTCJul 17, 14:35 UTC2h 10m
2026-07-17 UAL2477 - Jul 17, 07:14 UTCJul 17, 11:04 UTC3h 50m
2026-07-17 UAL2477 SFO → IND Jul 17, 07:02 UTCJul 17, 11:00 UTC3h 58m
2026-07-17 UAL504 - Jul 17, 00:25 UTCJul 17, 05:35 UTC5h 10m
2026-07-16 UAL2664 OAK → BWI Jul 16, 17:05 UTCJul 16, 21:50 UTC4h 45m
2026-07-16 UAL488 BUR → SFO Jul 16, 14:40 UTCJul 16, 15:35 UTC55m
2026-07-16 UAL1367 - Jul 16, 03:40 UTCJul 16, 04:30 UTC50m
2026-07-16 UAL2841 LAS → SFO Jul 16, 00:35 UTCJul 16, 01:45 UTC1h 10m
2026-07-15 UAL2855 - Jul 15, 21:50 UTCJul 15, 23:00 UTC1h 10m
2026-07-15 UAL795 - Jul 15, 14:40 UTCJul 15, 19:30 UTC4h 50m
2026-07-15 UAL795 RDU → SFO Jul 15, 14:25 UTCJul 15, 19:23 UTC4h 58m
2026-07-14 UAL1205 SFO → RDU Jul 14, 15:20 UTCJul 14, 20:15 UTC4h 55m
2026-07-14 UAL1125 OGG → SFO Jul 14, 09:05 UTCJul 14, 13:37 UTC4h 32m
2026-07-13 UAL2623 - Jul 13, 21:45 UTCJul 13, 22:20 UTC35m
2026-07-13 UAL267 PHL → SFO Jul 13, 15:15 UTCJul 13, 20:05 UTC4h 50m
2026-07-13 UAL2854 - Jul 13, 06:50 UTCJul 13, 11:50 UTC5h 0m
2026-07-12 UAL2384 YUL → SFO Jul 12, 23:05 UTCJul 13, 04:15 UTC5h 10m

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 N27277 page for operator, model, and routing details .

Mode-S A2B157 frequently asked

What is Mode-S code A2B157?
A2B157 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N27277.
Where is Mode-S A2B157 registered?
Mode-S code A2B157 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 A2B157 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:35 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A2B157, octal 50530527, decimal 10,662,231.
What flights does A2B157 operate?
Mode-S A2B157 has broadcast 20 distinct callsigns, including UAL2859, UAL1699, UAL368, UAL2409, UAL1678.