sensors Mode-S transponder

A1C557

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N213HA · AIRBUS A-321neo · operated by UMB BANK NA TRUSTEE

Hex
A1C557
Octal
50342527
Decimal
10,601,815
Country
US
Tail
N213HA
Type
A21N
No current signal · last broadcast 16h ago
Flights observed
8
Distinct callsigns
5
Country
US
Last broadcast
16h ago

Last known position

Most recent position reported by Mode-S A1C557.

Country allocation

The ICAO 24-bit address A1C557 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 5 distinct

Callsign Airline Flights Last seen
ASA868 - 3 2026-04-13
ASA867 - 2 2026-04-13
ASA873 Alaska Airlines 1 2026-04-14
ASA1165 - 1 2026-04-13
ASA1136 - 1 2026-04-13

Recent flights last 8

DateFlightRouteTakeoffLandingDuration
2026-04-14 ASA873 LIH → PDX Apr 14, 08:50 UTCApr 14, 09:05 UTC15m
2026-04-13 ASA867 - Apr 13, 20:15 UTCApr 13, 20:45 UTC30m
2026-04-13 ASA867 - Apr 13, 14:15 UTCApr 13, 15:55 UTC1h 40m
2026-04-13 ASA868 - Apr 13, 11:55 UTCApr 13, 12:10 UTC15m
2026-04-13 ASA868 - Apr 13, 10:35 UTCApr 13, 12:10 UTC1h 35m
2026-04-13 ASA868 - Apr 13, 06:35 UTCApr 13, 06:50 UTC15m
2026-04-13 ASA1165 - Apr 13, 04:20 UTCApr 13, 04:40 UTC20m
2026-04-13 ASA1136 - Apr 13, 02:20 UTCApr 13, 02:40 UTC20m

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 N213HA page for operator, model, and routing details .

Mode-S A1C557 frequently asked

What is Mode-S code A1C557?
A1C557 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N213HA.
Where is Mode-S A1C557 registered?
Mode-S code A1C557 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 A1C557 broadcasting right now?
No active broadcast right now. Last signal was 16h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1C557, octal 50342527, decimal 10,601,815.
What flights does A1C557 operate?
Mode-S A1C557 has broadcast 5 distinct callsigns, including ASA868, ASA867, ASA873, ASA1165, ASA1136.