Apparatus

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sensors Mode-S transponder

AA1FFC

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N751YX · EMBRAER ERJ-170-200 (long wing) · operated by UNITED AIRLINES INC

Hex
AA1FFC
Octal
52417774
Decimal
11,149,308
Country
US
Tail
N751YX
Type
E75L
No current signal · last broadcast Jul 26, 22:40 UTC
Flights observed
684
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:40 UTC

Last known position

Most recent position reported by Mode-S AA1FFC.

Country allocation

The ICAO 24-bit address AA1FFC 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
RPA3572 Republic Airlines 11 2026-05-17
RPA3634 - 8 2026-07-23
RPA3424 Republic Airlines 7 2026-06-01
RPA3708 - 6 2026-07-15
RPA3705 - 6 2026-06-29
RPA3620 - 6 2026-07-07
RPA3563 Republic Airlines 6 2026-07-26
RPA3561 Republic Airlines 6 2026-07-19
RPA3503 Republic Airlines 6 2026-06-01
RPA3495 Republic Airlines 6 2026-05-17
RPA3452 Republic Airlines 6 2026-06-01
RPA3448 Republic Airlines 6 2026-06-15
RPA3447 Republic Airlines 6 2026-07-26
RPA3404 Republic Airlines 6 2026-05-21
RPA3709 - 5 2026-07-09
RPA3691 - 5 2026-07-17
RPA3679 - 5 2026-07-08
RPA3662 - 5 2026-06-20
RPA3657 - 5 2026-07-09
RPA3639 Republic Airlines 5 2026-06-09

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 RPA3447 IAD → JAX Jul 26, 21:50 UTCJul 26, 22:40 UTC50m
2026-07-26 RPA3596 EWR → PIT Jul 26, 17:25 UTCJul 26, 18:55 UTC1h 30m
2026-07-26 RPA3638 JAX → EWR Jul 26, 14:55 UTCJul 26, 16:05 UTC1h 10m
2026-07-26 RPA3642 PWM → ORD Jul 26, 11:15 UTCJul 26, 13:25 UTC2h 10m
2026-07-26 RPA3563 MSY → EWR Jul 26, 02:45 UTCJul 26, 04:45 UTC2h 0m
2026-07-26 RPA3563 MSY → EWR Jul 26, 02:35 UTCJul 26, 04:46 UTC2h 11m
2026-07-26 RPA3714 EWR → ROC Jul 26, 00:00 UTCJul 26, 01:35 UTC1h 35m
2026-07-25 RPA3589 ROC → EWR Jul 25, 20:25 UTCJul 25, 21:36 UTC1h 11m
2026-07-25 RPA3589 ROC → EWR Jul 25, 20:20 UTCJul 25, 21:30 UTC1h 10m
2026-07-25 RPA3400 EWR → TVC Jul 25, 15:15 UTCJul 25, 18:40 UTC3h 25m
2026-07-25 RPA3431 BUF → EWR Jul 25, 10:25 UTCJul 25, 13:50 UTC3h 25m
2026-07-25 RPA3655 EWR → SDF Jul 25, 00:25 UTCJul 25, 01:00 UTC35m
2026-07-25 RPA3655 EWR → SDF Jul 25, 00:39 UTCJul 25, 01:21 UTC42m
2026-07-24 RPA3651 EWR → CVG Jul 24, 22:10 UTCJul 24, 23:15 UTC1h 5m
2026-07-24 RPA3413 EWR → CMH Jul 24, 16:50 UTCJul 24, 18:05 UTC1h 15m
2026-07-24 RPA3552 IAD → BOS Jul 24, 14:05 UTCJul 24, 15:15 UTC1h 10m
2026-07-24 RPA3438 BUF → EWR Jul 24, 10:20 UTCJul 24, 11:30 UTC1h 10m
2026-07-24 RPA3598 RDU → EWR Jul 24, 00:05 UTCJul 24, 00:55 UTC50m
2026-07-23 RPA3598 RDU → EWR Jul 23, 23:38 UTCJul 24, 00:51 UTC1h 13m
2026-07-23 RPA3440 BUF → EWR Jul 23, 20:30 UTCJul 23, 21:45 UTC1h 15m
2026-07-23 RPA3634 - Jul 23, 17:50 UTCJul 23, 18:55 UTC1h 5m
2026-07-23 RPA3507 EWR → DTW Jul 23, 14:50 UTCJul 23, 16:40 UTC1h 50m
2026-07-23 RPA3425 ORD → ROC Jul 23, 12:00 UTCJul 23, 13:15 UTC1h 15m
2026-07-22 RPA3707 RDU → EWR Jul 22, 19:15 UTCJul 22, 21:35 UTC2h 20m
2026-07-22 RPA3653 - Jul 22, 16:05 UTCJul 22, 18:00 UTC1h 55m
2026-07-22 RPA3661 - Jul 22, 11:15 UTCJul 22, 12:00 UTC45m
2026-07-21 RPA3669 ROC → EWR Jul 21, 14:22 UTCJul 21, 18:10 UTC3h 48m
2026-07-21 RPA3669 ROC → EWR Jul 21, 16:15 UTCJul 21, 18:10 UTC1h 55m
2026-07-21 RPA3700 - Jul 21, 10:45 UTCJul 21, 12:15 UTC1h 30m
2026-07-21 RPA3606 - Jul 21, 01:50 UTCJul 21, 03:15 UTC1h 25m
2026-07-20 RPA3564 CMH → EWR Jul 20, 22:05 UTCJul 21, 00:05 UTC2h 0m
2026-07-20 RPA3556 CVG → ORD Jul 20, 18:30 UTCJul 20, 20:30 UTC2h 0m
2026-07-20 RPA3648 YYZ → EWR Jul 20, 16:05 UTCJul 20, 17:15 UTC1h 10m
2026-07-20 RPA3431 BUF → EWR Jul 20, 13:50 UTCJul 20, 14:50 UTC1h 0m
2026-07-20 RPA3551 BOS → EWR Jul 20, 10:00 UTCJul 20, 11:20 UTC1h 20m
2026-07-20 RPA3551 BOS → EWR Jul 20, 10:13 UTCJul 20, 11:16 UTC1h 3m
2026-07-20 RPA3622 IAD → BTV Jul 20, 02:40 UTCJul 20, 03:55 UTC1h 15m
2026-07-20 RPA3622 IAD → BTV Jul 20, 02:39 UTCJul 20, 03:52 UTC1h 13m
2026-07-20 RPA3433 - Jul 20, 00:55 UTCJul 20, 01:40 UTC45m
2026-07-20 RPA3433 CLE → IAD Jul 20, 00:53 UTCJul 20, 01:44 UTC51m
2026-07-19 RPA3488 SAV → EWR Jul 19, 23:00 UTCJul 20, 00:00 UTC1h 0m
2026-07-19 RPA3488 SAV → EWR Jul 19, 23:05 UTCJul 19, 23:55 UTC50m
2026-07-19 RPA3530 - Jul 19, 20:35 UTCJul 19, 21:45 UTC1h 10m
2026-07-19 RPA3561 ORD → MSY Jul 19, 18:15 UTCJul 19, 19:35 UTC1h 20m
2026-07-19 RPA3656 LGA → IAD Jul 19, 15:55 UTCJul 19, 16:45 UTC50m
2026-07-19 RPA3682 IND → EWR Jul 19, 13:45 UTCJul 19, 14:25 UTC40m
2026-07-19 RPA3433 - Jul 19, 00:35 UTCJul 19, 01:25 UTC50m
2026-07-18 RPA3488 SAV → EWR Jul 18, 22:23 UTCJul 18, 23:07 UTC44m
2026-07-18 RPA3488 SAV → EWR Jul 18, 22:20 UTCJul 18, 23:00 UTC40m
2026-07-18 RPA3637 YYZ → IAD Jul 18, 19:35 UTCJul 18, 20:50 UTC1h 15m

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 N751YX page for operator, model, and routing details .

Mode-S AA1FFC frequently asked

What is Mode-S code AA1FFC?
AA1FFC is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N751YX.
Where is Mode-S AA1FFC registered?
Mode-S code AA1FFC 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 AA1FFC broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:40 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AA1FFC, octal 52417774, decimal 11,149,308.
What flights does AA1FFC operate?
Mode-S AA1FFC has broadcast 20 distinct callsigns, including RPA3572, RPA3634, RPA3424, RPA3708, RPA3705.