Apparatus

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sensors Mode-S transponder

A81BC4

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N621UP · BOEING 747-8 · operated by UNITED PARCEL SERVICE CO

Hex
A81BC4
Octal
52015704
Decimal
11,017,156
Country
US
Tail
N621UP
Type
B748
No current signal · last broadcast 12h ago
Flights observed
96
Distinct callsigns
20
Country
US
Last broadcast
12h ago

Last known position

Most recent position reported by Mode-S A81BC4.

Country allocation

The ICAO 24-bit address A81BC4 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
UPS67 United Parcel Service 10 2026-04-15
UPS61 United Parcel Service 10 2026-05-21
UPS71 United Parcel Service 9 2026-04-24
UPS203 United Parcel Service 6 2026-05-28
UPS81 United Parcel Service 5 2026-05-01
UPS14 United Parcel Service 4 2026-05-29
UPS94 United Parcel Service 3 2026-04-23
UPS62 United Parcel Service 3 2026-05-05
UPS5967 United Parcel Service 3 2026-04-26
UPS32 United Parcel Service 3 2026-05-23
UPS28 United Parcel Service 3 2026-04-17
UPS109 United Parcel Service 3 2026-04-18
UPS99 United Parcel Service 2 2026-05-26
UPS80 United Parcel Service 2 2026-04-29
UPS77 United Parcel Service 2 2026-04-29
UPS76 United Parcel Service 2 2026-04-27
UPS68 United Parcel Service 2 2026-04-14
UPS61D United Parcel Service 2 2026-05-21
UPS6061 United Parcel Service 2 2026-05-22
UPS568 United Parcel Service 2 2026-05-03

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-05-29 UPS14 CGN → BKK May 29, 14:55 UTCMay 29, 15:05 UTC10m
2026-05-29 UPS14 CGN → BKK May 29, 03:55 UTCMay 29, 07:35 UTC3h 40m
2026-05-28 UPS203 PHL → CGN May 28, 13:25 UTCMay 28, 20:15 UTC6h 50m
2026-05-28 UPS204 CGN → PHL May 28, 03:00 UTCMay 28, 10:20 UTC7h 20m
2026-05-27 UPS213 SDF → CGN May 27, 09:25 UTCMay 27, 11:35 UTC2h 10m
2026-05-27 UPS213 SDF → CGN May 27, 09:15 UTCMay 27, 17:14 UTC7h 59m
2026-05-26 UPS99 ICN → ANC May 26, 00:49 UTCMay 26, 06:29 UTC5h 40m
2026-05-25 UPS99 ICN → ANC May 25, 14:40 UTCMay 25, 22:34 UTC7h 55m
2026-05-25 UPS37 HNL → SDF May 25, 02:25 UTCMay 25, 12:45 UTC10h 20m
2026-05-24 UPS34 SDF → SYD May 24, 00:10 UTCMay 24, 09:55 UTC9h 45m
2026-05-24 UPS34 SDF → SYD May 24, 00:14 UTCMay 24, 09:56 UTC9h 42m
2026-05-23 UPS32 SDF → HNL May 23, 17:25 UTCMay 23, 17:50 UTC25m
2026-05-23 UPS32 SDF → HNL May 23, 09:20 UTCMay 23, 13:45 UTC4h 25m
2026-05-23 UPS32 SDF → HNL May 23, 09:13 UTCMay 23, 17:37 UTC8h 24m
2026-05-22 UPS6061 ANC → SDF May 22, 21:05 UTCMay 23, 00:40 UTC3h 35m
2026-05-22 UPS6061 ANC → SDF May 22, 20:55 UTCMay 23, 00:37 UTC3h 42m
2026-05-21 UPS61 TPE → ANC May 21, 23:10 UTCMay 22, 03:35 UTC4h 25m
2026-05-21 UPS61 TPE → ANC May 21, 23:03 UTCMay 22, 03:26 UTC4h 23m
2026-05-21 UPS61D HKG → ANC May 21, 14:00 UTCMay 21, 20:50 UTC6h 50m
2026-05-21 UPS61D HKG → ANC May 21, 12:35 UTCMay 21, 12:50 UTC15m
2026-05-06 UPS61 TPE → ANC May 6, 09:15 UTCMay 6, 09:40 UTC25m
2026-05-06 UPS61 TPE → ANC May 6, 08:25 UTCMay 6, 08:40 UTC15m
2026-05-05 UPS62 ANC → HKG May 5, 18:31 UTCMay 6, 05:13 UTC10h 42m
2026-05-05 UPS62 ANC → HKG May 5, 18:30 UTCMay 5, 20:05 UTC1h 35m
2026-05-05 UPS62 ANC → HKG May 5, 08:05 UTCMay 5, 14:45 UTC6h 40m
2026-05-05 UPS559 MSP → SDF May 5, 02:46 UTCMay 5, 04:20 UTC1h 34m
2026-05-05 UPS559 MSP → SDF May 5, 02:50 UTCMay 5, 04:30 UTC1h 40m
2026-05-03 UPS568 SDF → MSP May 3, 20:45 UTCMay 3, 22:20 UTC1h 35m
2026-05-03 UPS568 SDF → MSP May 3, 20:34 UTCMay 3, 22:16 UTC1h 42m
2026-05-03 UPS61 TPE → ANC May 3, 06:29 UTCMay 3, 11:37 UTC5h 8m
2026-05-03 UPS61 TPE → ANC May 3, 06:29 UTCMay 3, 11:33 UTC5h 4m
2026-05-03 UPS61 TPE → ANC May 3, 06:25 UTCMay 3, 09:00 UTC2h 35m
2026-05-02 UPS61 TPE → ANC May 2, 22:30 UTCMay 3, 04:55 UTC6h 24m
2026-05-02 UPS61 TPE → ANC May 2, 20:40 UTCMay 2, 20:50 UTC10m
2026-05-02 UPS61 TPE → ANC May 2, 15:20 UTCMay 2, 16:45 UTC1h 25m
2026-05-01 UPS1938 HNL → HKG May 1, 19:35 UTCMay 1, 20:00 UTC25m
2026-05-01 UPS1938 HNL → HKG May 1, 19:34 UTCMay 2, 06:33 UTC10h 59m
2026-05-01 UPS56 SDF → ANC May 1, 10:20 UTCMay 1, 11:00 UTC40m
2026-05-01 UPS56 SDF → ANC May 1, 10:16 UTCMay 1, 15:28 UTC5h 12m
2026-05-01 UPS81 PVG → SDF May 1, 00:00 UTCMay 1, 04:25 UTC4h 25m
2026-04-30 UPS81 PVG → SDF Apr 30, 23:59 UTCMay 1, 04:23 UTC4h 24m
2026-04-30 UPS81 PVG → SDF Apr 30, 21:55 UTCApr 30, 22:00 UTC5m
2026-04-30 UPS81 PVG → SDF Apr 30, 14:40 UTCApr 30, 15:50 UTC1h 10m
2026-04-30 UPS81 PVG → SDF Apr 30, 13:42 UTCApr 30, 21:40 UTC7h 58m
2026-04-29 UPS80 SDF → PVG Apr 29, 21:05 UTCApr 29, 21:45 UTC40m
2026-04-29 UPS80 SDF → PVG Apr 29, 20:53 UTCApr 30, 06:23 UTC9h 30m
2026-04-29 UPS64 SDF → ANC Apr 29, 08:10 UTCApr 29, 14:25 UTC6h 16m
2026-04-29 UPS77 ANC → SDF Apr 29, 00:15 UTCApr 29, 05:45 UTC5h 30m
2026-04-28 UPS77 ANC → SDF Apr 28, 12:35 UTCApr 28, 22:00 UTC9h 25m
2026-04-27 UPS76 SDF → DWC Apr 27, 20:00 UTCApr 28, 04:05 UTC8h 5m

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 N621UP page for operator, model, and routing details .

Mode-S A81BC4 frequently asked

What is Mode-S code A81BC4?
A81BC4 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N621UP.
Where is Mode-S A81BC4 registered?
Mode-S code A81BC4 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 A81BC4 broadcasting right now?
No active broadcast right now. Last signal was 12h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A81BC4, octal 52015704, decimal 11,017,156.
What flights does A81BC4 operate?
Mode-S A81BC4 has broadcast 20 distinct callsigns, including UPS67, UPS61, UPS71, UPS203, UPS81.