Apparatus

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sensors Mode-S transponder

4B1691

ICAO 24-bit transponder address · allocated to Switzerland

Currently assigned to HB-IOF · AIRBUS A-321

Hex
4B1691
Octal
22613221
Decimal
4,920,977
Country
CH
Tail
HB-IOF
Type
A321
No current signal · last broadcast 3h ago
Flights observed
346
Distinct callsigns
20
Country
CH
Last broadcast
3h ago

Last known position

Most recent position reported by Mode-S 4B1691.

Country allocation

The ICAO 24-bit address 4B1691 falls within the block assigned to Switzerland (CH) by ICAO Annex 10, Volume III. Every aircraft registered in Switzerland 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
SWR1LK - 8 2026-06-19
SWR87C - 7 2026-06-22
SWR4TD Swiss International Air Lines 7 2026-06-22
SWR4ET - 7 2026-06-19
SWR493Z - 7 2026-07-04
SWR27G - 7 2026-07-04
SWR9TP - 6 2026-07-11
SWR5AM - 6 2026-07-01
SWR3ZK - 6 2026-07-11
SWR9PX - 5 2026-07-12
SWR589X - 5 2026-07-12
SWR2XH Swiss International Air Lines 5 2026-04-26
SWR26W - 5 2026-07-13
SWR1ZB - 5 2026-07-01
SWR98P Swiss International Air Lines 4 2026-04-26
SWR96M - 4 2026-07-09
SWR92W Swiss International Air Lines 4 2026-05-23
SWR915W Swiss International Air Lines 4 2026-06-11
SWR7VE - 4 2026-07-13
SWR5CB - 4 2026-07-08

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 SWR20D OPO → ZRH Jul 14, 12:30 UTCJul 14, 14:30 UTC2h 0m
2026-07-14 SWR8BC ZRH → OPO Jul 14, 08:05 UTCJul 14, 10:25 UTC2h 20m
2026-07-13 SWR26W CPH → ZRH Jul 13, 14:15 UTCJul 13, 15:45 UTC1h 30m
2026-07-13 SWR7VE ZRH → CPH Jul 13, 10:55 UTCJul 13, 12:15 UTC1h 20m
2026-07-13 SWR4CX BEG → ZRH Jul 13, 07:55 UTCJul 13, 09:30 UTC1h 35m
2026-07-13 SWR464L ZRH → BEG Jul 13, 05:15 UTCJul 13, 06:35 UTC1h 20m
2026-07-12 SWR8KY PRG → ZRH Jul 12, 20:20 UTCJul 12, 21:25 UTC1h 5m
2026-07-12 SWR1488 ZRH → PRG Jul 12, 18:15 UTCJul 12, 19:15 UTC1h 0m
2026-07-12 SWR589X ARN → ZRH Jul 12, 14:45 UTCJul 12, 17:01 UTC2h 15m
2026-07-12 SWR9PX ZRH → ARN Jul 12, 11:05 UTCJul 12, 13:05 UTC2h 0m
2026-07-12 SWR5PT - Jul 12, 07:40 UTCJul 12, 08:50 UTC1h 10m
2026-07-12 SWR433Y ZRH → HAM Jul 12, 05:20 UTCJul 12, 06:30 UTC1h 10m
2026-07-11 SWR9TP GVA → ZRH Jul 11, 18:30 UTCJul 11, 19:00 UTC30m
2026-07-11 SWR3ZK ZRH → GVA Jul 11, 16:35 UTCJul 11, 17:10 UTC35m
2026-07-11 SWR5YW - Jul 11, 13:50 UTCJul 11, 15:00 UTC1h 10m
2026-07-11 SWR5LD - Jul 11, 11:20 UTCJul 11, 12:30 UTC1h 10m
2026-07-11 SWR5103 - Jul 11, 07:40 UTCJul 11, 08:20 UTC40m
2026-07-09 SWR4TH ZRH → GVA Jul 9, 19:35 UTCJul 9, 20:05 UTC30m
2026-07-09 SWR2GX LIS → ZRH Jul 9, 15:30 UTCJul 9, 17:55 UTC2h 25m
2026-07-09 SWR2BK ZRH → LIS Jul 9, 11:35 UTCJul 9, 14:00 UTC2h 25m
2026-07-09 SWR96M BCN → ZRH Jul 9, 08:10 UTCJul 9, 09:40 UTC1h 30m
2026-07-09 SWR44Y ZRH → BCN Jul 9, 05:40 UTCJul 9, 07:00 UTC1h 20m
2026-07-08 SWR9TP - Jul 8, 18:10 UTCJul 8, 18:40 UTC30m
2026-07-08 SWR3ZK ZRH → GVA Jul 8, 16:30 UTCJul 8, 17:05 UTC35m
2026-07-08 SWR5CB - Jul 8, 14:05 UTCJul 8, 15:00 UTC55m
2026-07-08 SWR1PL ZRH → BER Jul 8, 11:30 UTCJul 8, 12:40 UTC1h 10m
2026-07-07 SWR8AK MAN → ZRH Jul 7, 18:20 UTCJul 7, 19:55 UTC1h 35m
2026-07-07 SWR9TC ZRH → MAN Jul 7, 15:25 UTCJul 7, 17:00 UTC1h 35m
2026-07-06 SWR589X ARN → ZRH Jul 6, 14:10 UTCJul 6, 16:15 UTC2h 5m
2026-07-06 SWR9PX ZRH → ARN Jul 6, 10:35 UTCJul 6, 12:50 UTC2h 15m
2026-07-06 SWR339H - Jul 6, 08:45 UTCJul 6, 09:15 UTC30m
2026-07-06 SWR5CV ZRH → LUX Jul 6, 06:45 UTCJul 6, 07:25 UTC40m
2026-07-06 SWR4VE BCN → ZRH Jul 6, 04:15 UTCJul 6, 05:35 UTC1h 20m
2026-07-05 SWR4KB ZRH → BCN Jul 5, 20:25 UTCJul 5, 21:40 UTC1h 15m
2026-07-05 SWR5XH - Jul 5, 16:50 UTCJul 5, 18:30 UTC1h 40m
2026-07-05 SWR2EG - Jul 5, 14:00 UTCJul 5, 15:25 UTC1h 25m
2026-07-04 SWR493Z HAM → ZRH Jul 4, 14:05 UTCJul 4, 15:10 UTC1h 5m
2026-07-04 SWR27G ZRH → HAM Jul 4, 11:15 UTCJul 4, 12:30 UTC1h 15m
2026-07-04 SWR2WX - Jul 4, 08:05 UTCJul 4, 09:30 UTC1h 25m
2026-07-04 SWR193T ZRH → CPH Jul 4, 05:25 UTCJul 4, 06:55 UTC1h 30m
2026-07-03 SWR5TV OPO → ZRH Jul 3, 19:00 UTCJul 3, 21:05 UTC2h 5m
2026-07-03 SWR82L ZRH → OPO Jul 3, 15:35 UTCJul 3, 17:45 UTC2h 10m
2026-07-03 SWR935L ATH → ZRH Jul 3, 11:35 UTCJul 3, 14:05 UTC2h 30m
2026-07-03 SWR9LA ZRH → ATH Jul 3, 08:10 UTCJul 3, 10:20 UTC2h 10m
2026-07-03 SWR1PM ARN → ZRH Jul 3, 04:25 UTCJul 3, 06:25 UTC2h 0m
2026-07-02 SWR1KV ZRH → ARN Jul 2, 20:25 UTCJul 2, 22:25 UTC2h 0m
2026-07-02 SWR388G HAM → ZRH Jul 2, 18:00 UTCJul 2, 19:10 UTC1h 10m
2026-07-02 SWR1TX ZRH → HAM Jul 2, 15:25 UTCJul 2, 16:30 UTC1h 5m
2026-07-02 SWR2YB ARN → ZRH Jul 2, 11:20 UTCJul 2, 13:30 UTC2h 10m
2026-07-02 SWR5ZM ZRH → ARN Jul 2, 08:05 UTCJul 2, 10:15 UTC2h 10m

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 HB-IOF page for operator, model, and routing details .

Mode-S 4B1691 frequently asked

What is Mode-S code 4B1691?
4B1691 is an ICAO 24-bit transponder address. Allocated to Switzerland. Assigned to HB-IOF.
Where is Mode-S 4B1691 registered?
Mode-S code 4B1691 is allocated to Switzerland (CH). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4B1691 broadcasting right now?
No active broadcast right now. Last signal was 3h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4B1691, octal 22613221, decimal 4,920,977.
What flights does 4B1691 operate?
Mode-S 4B1691 has broadcast 20 distinct callsigns, including SWR1LK, SWR87C, SWR4TD, SWR4ET, SWR493Z.