Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A00B91

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N10156 · EMBRAER ERJ-145XR · operated by UNITED AIRLINES INC

Hex
A00B91
Octal
50005621
Decimal
10,488,721
Country
US
Tail
N10156
Type
E45X
No current signal · last broadcast 1d ago
Flights observed
3
Distinct callsigns
2
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A00B91.

Country allocation

The ICAO 24-bit address A00B91 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 2 distinct

Callsign Airline Flights Last seen
UCA4312 - 2 2026-04-13
UCA4989 CommutAir 1 2026-04-13

Recent flights last 3

DateFlightRouteTakeoffLandingDuration
2026-04-13 UCA4989 MOB → IAH Apr 13, 14:12 UTCApr 13, 15:40 UTC1h 28m
2026-04-13 UCA4312 - Apr 13, 03:55 UTCApr 13, 04:10 UTC15m
2026-04-13 UCA4312 - Apr 13, 03:08 UTCApr 13, 04:20 UTC1h 12m

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 N10156 page for operator, model, and routing details .

Mode-S A00B91 frequently asked

What is Mode-S code A00B91?
A00B91 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N10156.
Where is Mode-S A00B91 registered?
Mode-S code A00B91 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 A00B91 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 A00B91, octal 50005621, decimal 10,488,721.
What flights does A00B91 operate?
Mode-S A00B91 has broadcast 2 distinct callsigns, including UCA4312, UCA4989.