Apparatus

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sensors Mode-S transponder

A081CA

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N13138 · BOEING 757-200 · operated by UNITED AIRLINES INC

Hex
A081CA
Octal
50100712
Decimal
10,518,986
Country
US
Tail
N13138
Type
B752
No current signal · last broadcast Jul 25, 18:20 UTC
Flights observed
61
Distinct callsigns
20
Country
US
Last broadcast
Jul 25, 18:20 UTC

Last known position

Most recent position reported by Mode-S A081CA.

Country allocation

The ICAO 24-bit address A081CA 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
UAL229 United Airlines 5 2026-07-18
UAL978 United Airlines 4 2026-07-22
UAL979 United Airlines 3 2026-07-22
UAL2743 - 3 2026-07-11
UAL228 United Airlines 3 2026-07-18
UAL1758 - 3 2026-07-08
UAL663K - 2 2026-07-06
UAL3872 - 2 2026-06-30
UAL3860 United Airlines 2 2026-05-14
UAL36 - 2 2026-07-06
UAL274 United Airlines 2 2026-07-24
UAL2679 United Airlines 2 2026-07-23
UAL2115 United Airlines 2 2026-07-24
UAL1759 - 2 2026-07-08
UAL145 - 2 2026-07-04
UAL144 - 2 2026-07-04
UAL138 United Airlines 2 2026-07-25
UAL1283 - 2 2026-07-08
UAL913 United Airlines 1 2026-07-25
UAL3933 - 1 2026-07-11

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-25 UAL913 HNL → SFO Jul 25, 12:05 UTCJul 25, 18:20 UTC6h 15m
2026-07-25 UAL138 KEF → EWR Jul 25, 06:35 UTCJul 25, 06:55 UTC20m
2026-07-25 UAL138 KEF → EWR Jul 25, 02:00 UTCJul 25, 04:00 UTC2h 0m
2026-07-24 UAL274 RDU → EWR Jul 24, 19:00 UTCJul 24, 23:50 UTC4h 50m
2026-07-24 UAL2115 MIA → EWR Jul 24, 10:20 UTCJul 24, 15:50 UTC5h 30m
2026-07-24 UAL2115 MIA → EWR Jul 24, 10:19 UTCJul 24, 15:45 UTC5h 26m
2026-07-23 UAL1700 IAH → EWR Jul 23, 23:40 UTCJul 24, 04:25 UTC4h 45m
2026-07-23 UAL2679 DEN → ORD Jul 23, 15:07 UTCJul 23, 20:31 UTC5h 24m
2026-07-23 UAL2679 DEN → ORD Jul 23, 15:05 UTCJul 23, 20:25 UTC5h 20m
2026-07-23 UAL3923 MCO → EWR Jul 23, 13:05 UTCJul 23, 13:50 UTC45m
2026-07-22 UAL979 EDI → IAD Jul 22, 13:05 UTCJul 22, 20:35 UTC7h 30m
2026-07-22 UAL978 IAD → EDI Jul 22, 11:10 UTCJul 22, 11:30 UTC20m
2026-07-22 UAL978 IAD → EDI Jul 22, 04:45 UTCJul 22, 10:25 UTC5h 40m
2026-07-21 UAL979 EDI → IAD Jul 21, 11:45 UTCJul 21, 20:00 UTC8h 15m
2026-07-21 UAL978 IAD → EDI Jul 21, 02:55 UTCJul 21, 09:40 UTC6h 45m
2026-07-19 UAL979 EDI → IAD Jul 19, 11:40 UTCJul 19, 19:20 UTC7h 40m
2026-07-19 UAL978 IAD → EDI Jul 19, 03:00 UTCJul 19, 09:35 UTC6h 35m
2026-07-18 UAL229 BZN → SFO Jul 18, 20:00 UTCJul 18, 20:05 UTC5m
2026-07-18 UAL229 BZN → SFO Jul 18, 12:10 UTCJul 18, 20:05 UTC7h 55m
2026-07-18 UAL229 BZN → SFO Jul 18, 11:51 UTCJul 18, 19:45 UTC7h 54m
2026-07-18 UAL228 IAD → DUB Jul 18, 03:15 UTCJul 18, 09:55 UTC6h 40m
2026-07-18 UAL228 IAD → DUB Jul 18, 02:50 UTCJul 18, 09:47 UTC6h 57m
2026-07-17 UAL311 DUB → IAD Jul 17, 09:25 UTCJul 17, 16:29 UTC7h 5m
2026-07-17 UAL310 IAD → DUB Jul 17, 00:30 UTCJul 17, 06:54 UTC6h 25m
2026-07-16 UAL229 DUB → IAD Jul 16, 11:40 UTCJul 16, 18:50 UTC7h 10m
2026-07-16 UAL228 IAD → DUB Jul 16, 03:10 UTCJul 16, 09:55 UTC6h 45m
2026-07-15 UAL229 - Jul 15, 11:55 UTCJul 15, 19:00 UTC7h 5m
2026-07-15 UAL317 EWR → DUB Jul 15, 03:30 UTCJul 15, 09:45 UTC6h 15m
2026-07-12 UAL327 - Jul 12, 05:10 UTCJul 12, 09:55 UTC4h 45m
2026-07-11 UAL210 - Jul 11, 22:05 UTCJul 12, 03:05 UTC5h 0m
2026-07-11 UAL2743 - Jul 11, 14:15 UTCJul 11, 19:05 UTC4h 50m
2026-07-11 UAL2743 LAX → EWR Jul 11, 14:19 UTCJul 11, 19:09 UTC4h 50m
2026-07-11 UAL3933 - Jul 11, 01:10 UTCJul 11, 02:05 UTC55m
2026-07-10 UAL1558 - Jul 10, 00:35 UTCJul 10, 06:35 UTC6h 0m
2026-07-08 UAL1283 DEN → EWR Jul 8, 19:10 UTCJul 8, 22:20 UTC3h 10m
2026-07-08 UAL1283 DEN → EWR Jul 8, 19:13 UTCJul 8, 22:18 UTC3h 5m
2026-07-08 UAL1759 - Jul 8, 10:10 UTCJul 8, 12:20 UTC2h 10m
2026-07-08 UAL1759 - Jul 8, 06:00 UTCJul 8, 06:10 UTC10m
2026-07-08 UAL1758 - Jul 8, 01:15 UTCJul 8, 01:35 UTC20m
2026-07-07 UAL1758 - Jul 7, 18:45 UTCJul 7, 21:20 UTC2h 35m
2026-07-07 UAL1758 DEN → KOA Jul 7, 18:38 UTCJul 8, 01:31 UTC6h 53m
2026-07-06 UAL663K EWR → DEN Jul 6, 20:46 UTCJul 7, 00:32 UTC3h 46m
2026-07-06 UAL663K EWR → DEN Jul 6, 20:30 UTCJul 7, 00:35 UTC4h 5m
2026-07-06 UAL37 - Jul 6, 08:50 UTCJul 6, 15:55 UTC7h 5m
2026-07-06 UAL36 - Jul 6, 00:45 UTCJul 6, 02:20 UTC1h 35m
2026-07-06 UAL36 EWR → EDI Jul 6, 00:38 UTCJul 6, 06:46 UTC6h 8m
2026-07-05 UAL1149 EWR → SRQ Jul 5, 16:15 UTCJul 5, 21:10 UTC4h 55m
2026-07-04 UAL1340 EWR → SFO Jul 4, 22:00 UTCJul 5, 03:40 UTC5h 40m
2026-07-04 UAL145 OPO → EWR Jul 4, 12:15 UTCJul 4, 19:20 UTC7h 5m
2026-07-04 UAL144 EWR → OPO Jul 4, 03:50 UTCJul 4, 10:20 UTC6h 30m

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 N13138 page for operator, model, and routing details .

Mode-S A081CA frequently asked

What is Mode-S code A081CA?
A081CA is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N13138.
Where is Mode-S A081CA registered?
Mode-S code A081CA 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 A081CA broadcasting right now?
No active broadcast right now. Last signal was Jul 25, 18:20 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A081CA, octal 50100712, decimal 10,518,986.
What flights does A081CA operate?
Mode-S A081CA has broadcast 20 distinct callsigns, including UAL229, UAL978, UAL979, UAL2743, UAL228.