sensors Mode-S transponder

A8102A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N61898 · BOEING 737-900 · operated by UNITED AIRLINES INC

Hex
A8102A
Octal
52010052
Decimal
11,014,186
Country
US
Tail
N61898
Type
B739
No current signal · last broadcast 1d ago
Flights observed
8
Distinct callsigns
4
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A8102A.

Country allocation

The ICAO 24-bit address A8102A 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 4 distinct

Callsign Airline Flights Last seen
UAL1101 United Airlines 3 2026-04-13
UAL582 United Airlines 2 2026-04-13
UAL431 - 2 2026-04-13
UAL677 - 1 2026-04-12

Recent flights last 8

DateFlightRouteTakeoffLandingDuration
2026-04-13 UAL431 - Apr 13, 19:50 UTCApr 13, 22:00 UTC2h 10m
2026-04-13 UAL431 - Apr 13, 18:42 UTCApr 13, 22:22 UTC3h 40m
2026-04-13 UAL1101 MCO → EWR Apr 13, 16:15 UTCApr 13, 16:40 UTC25m
2026-04-13 UAL1101 MCO → EWR Apr 13, 15:50 UTCApr 13, 16:40 UTC50m
2026-04-13 UAL1101 MCO → EWR Apr 13, 14:03 UTCApr 13, 17:09 UTC3h 6m
2026-04-13 UAL582 YYC → SFO Apr 13, 03:55 UTCApr 13, 04:10 UTC15m
2026-04-13 UAL582 YYC → SFO Apr 13, 00:35 UTCApr 13, 04:10 UTC3h 35m
2026-04-12 UAL677 - Apr 12, 17:15 UTCApr 12, 17:50 UTC35m

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 N61898 page for operator, model, and routing details .

Mode-S A8102A frequently asked

What is Mode-S code A8102A?
A8102A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N61898.
Where is Mode-S A8102A registered?
Mode-S code A8102A 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 A8102A broadcasting right now?
No active broadcast right now. Last signal was 1d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A8102A, octal 52010052, decimal 11,014,186.
What flights does A8102A operate?
Mode-S A8102A has broadcast 4 distinct callsigns, including UAL1101, UAL582, UAL431, UAL677.