Apparatus

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sensors Mode-S transponder

A8521F

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N635UP · BOEING 747-8 · operated by UNITED PARCEL SERVICE CO

Hex
A8521F
Octal
52051037
Decimal
11,031,071
Country
US
Tail
N635UP
Type
B748
Broadcasting now · callsign UPS32 · 36,000 ft
Flights observed
218
Distinct callsigns
20
Country
US
Last broadcast
1h ago

Current position

A8521F is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A8521F 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
UPS77 - 21 2026-07-14
UPS76 - 21 2026-07-11
UPS216 - 14 2026-07-04
UPS99 - 9 2026-06-16
UPS32 - 9 2026-07-14
UPS72 - 8 2026-06-19
UPS64 United Parcel Service 7 2026-05-29
UPS109 - 7 2026-07-09
UPS9 United Parcel Service 6 2026-05-19
UPS94 United Parcel Service 5 2026-05-23
UPS70 United Parcel Service 5 2026-06-06
UPS63 United Parcel Service 5 2026-06-09
UPS34 - 5 2026-06-13
UPS210 United Parcel Service 5 2026-06-21
UPS69 United Parcel Service 4 2026-06-27
UPS5967 - 4 2026-06-18
UPS59 United Parcel Service 4 2026-05-31
UPS56 United Parcel Service 4 2026-06-04
UPS35 United Parcel Service 4 2026-04-27
UPS217 United Parcel Service 4 2026-04-15

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 UPS32 - Jul 14, 08:30 UTCJul 14, 09:45 UTC1h 15m
2026-07-14 UPS77 - Jul 14, 00:00 UTCJul 14, 05:35 UTC5h 35m
2026-07-13 UPS77 - Jul 13, 11:45 UTCJul 13, 21:35 UTC9h 50m
2026-07-11 UPS76 - Jul 11, 21:30 UTCJul 12, 05:01 UTC7h 30m
2026-07-11 UPS76 - Jul 11, 10:45 UTCJul 11, 16:45 UTC6h 0m
2026-07-09 UPS109 - Jul 9, 23:25 UTCJul 10, 05:05 UTC5h 40m
2026-07-09 UPS109 ANC → SDF Jul 9, 23:22 UTCJul 10, 04:58 UTC5h 36m
2026-07-09 UPS109 - Jul 9, 15:00 UTCJul 9, 21:30 UTC6h 30m
2026-07-09 UPS109 - Jul 9, 01:05 UTCJul 9, 13:25 UTC12h 20m
2026-07-08 UPS108 - Jul 8, 10:15 UTCJul 8, 22:25 UTC12h 10m
2026-07-08 UPS77 - Jul 8, 02:00 UTCJul 8, 02:55 UTC55m
2026-07-08 UPS77 ANC → SDF Jul 8, 01:47 UTCJul 8, 07:49 UTC6h 2m
2026-07-07 UPS77 - Jul 7, 14:15 UTCJul 8, 00:00 UTC9h 45m
2026-07-06 UPS76 SDF → DWC Jul 6, 20:00 UTCJul 7, 06:03 UTC10h 3m
2026-07-06 UPS76 SDF → DWC Jul 6, 20:00 UTCJul 6, 20:45 UTC45m
2026-07-05 UPS76 SDF → DWC Jul 5, 22:35 UTCJul 6, 04:25 UTC5h 50m
2026-07-04 UPS216 - Jul 4, 06:40 UTCJul 4, 07:45 UTC1h 5m
2026-07-04 UPS216 CGN → SDF Jul 4, 06:37 UTCJul 4, 15:15 UTC8h 38m
2026-07-04 UPS216 CGN → SDF Jul 4, 06:37 UTCJul 4, 15:15 UTC8h 38m
2026-07-03 UPS203 - Jul 3, 13:45 UTCJul 3, 15:30 UTC1h 45m
2026-07-03 UPS203 PHL → CGN Jul 3, 13:42 UTCJul 3, 20:21 UTC6h 39m
2026-07-03 UPS204 - Jul 3, 03:00 UTCJul 3, 05:05 UTC2h 5m
2026-07-03 UPS204 CGN → PHL Jul 3, 02:48 UTCJul 3, 11:00 UTC8h 12m
2026-07-02 UPS17 DEL → CGN Jul 2, 09:40 UTCJul 2, 17:55 UTC8h 15m
2026-07-01 UPS20 CGN → DEL Jul 1, 19:35 UTCJul 2, 03:10 UTC7h 35m
2026-06-30 UPS223 - Jun 30, 07:40 UTCJun 30, 10:15 UTC2h 35m
2026-06-30 UPS223 SDF → CGN Jun 30, 07:36 UTCJun 30, 15:11 UTC7h 35m
2026-06-27 UPS69 HKG → SDF Jun 27, 18:49 UTCJun 28, 00:43 UTC5h 54m
2026-06-27 UPS69 HKG → SDF Jun 27, 19:00 UTCJun 28, 00:45 UTC5h 45m
2026-06-27 UPS69 HKG → SDF Jun 27, 08:20 UTCJun 27, 16:44 UTC8h 25m
2026-06-27 UPS69 HKG → SDF Jun 27, 07:34 UTCJun 27, 07:49 UTC15m
2026-06-26 UPS4 STN → TPE Jun 26, 19:39 UTCJun 26, 20:00 UTC20m
2026-06-26 UPS4 STN → TPE Jun 26, 08:50 UTCJun 26, 11:34 UTC2h 45m
2026-06-26 UPS4 STN → TPE Jun 26, 01:45 UTCJun 26, 02:30 UTC45m
2026-06-25 UPS17 - Jun 25, 08:45 UTCJun 25, 16:45 UTC8h 0m
2026-06-24 UPS20 CGN → DEL Jun 24, 20:09 UTCJun 25, 03:40 UTC7h 30m
2026-06-24 UPS213 - Jun 24, 09:34 UTCJun 24, 17:05 UTC7h 30m
2026-06-23 UPS77 - Jun 23, 23:44 UTCJun 24, 05:24 UTC5h 40m
2026-06-23 UPS77 - Jun 23, 11:40 UTCJun 23, 21:39 UTC10h 0m
2026-06-23 UPS76 SDF → DWC Jun 23, 06:24 UTCJun 23, 06:34 UTC10m
2026-06-22 UPS76 SDF → DWC Jun 22, 20:04 UTCJun 23, 04:05 UTC8h 0m
2026-06-21 UPS76 SDF → DWC Jun 21, 21:29 UTCJun 21, 21:44 UTC15m
2026-06-21 UPS76 SDF → DWC Jun 21, 21:13 UTCJun 22, 03:32 UTC6h 19m
2026-06-21 UPS210 CGN → PHL Jun 21, 05:49 UTCJun 21, 14:15 UTC8h 25m
2026-06-21 UPS210 CGN → PHL Jun 21, 05:49 UTCJun 21, 14:12 UTC8h 23m
2026-06-20 UPS209 PHL → CGN Jun 20, 18:45 UTCJun 21, 02:10 UTC7h 25m
2026-06-20 UPS209 PHL → CGN Jun 20, 18:38 UTCJun 21, 02:08 UTC7h 30m
2026-06-20 UPS71 - Jun 20, 09:19 UTCJun 20, 13:44 UTC4h 25m
2026-06-19 UPS71 - Jun 19, 21:34 UTCJun 20, 07:24 UTC9h 50m
2026-06-19 UPS74 ONT → SDF Jun 19, 17:14 UTCJun 19, 17:34 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 N635UP page for operator, model, and routing details .

Mode-S A8521F frequently asked

What is Mode-S code A8521F?
A8521F is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N635UP.
Where is Mode-S A8521F registered?
Mode-S code A8521F 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 A8521F broadcasting right now?
Yes. Mode-S A8521F is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A8521F, octal 52051037, decimal 11,031,071.
What flights does A8521F operate?
Mode-S A8521F has broadcast 20 distinct callsigns, including UPS77, UPS76, UPS216, UPS99, UPS32.