Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A661BF

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N510DE · AIRBUS A-321neo · operated by DELTA AIR LINES INC

Hex
A661BF
Octal
51460677
Decimal
10,903,999
Country
US
Tail
N510DE
Type
A21N
No current signal · last broadcast Jul 26, 21:45 UTC
Flights observed
446
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:45 UTC

Last known position

Most recent position reported by Mode-S A661BF.

Country allocation

The ICAO 24-bit address A661BF 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
DAL1780 - 17 2026-06-30
DAL506 - 9 2026-07-11
DAL443 - 8 2026-07-10
DAL422 - 8 2026-07-10
DAL351 - 8 2026-07-17
DAL324 Delta Air Lines 8 2026-06-12
DAL1961 Delta Air Lines 8 2026-04-22
DAL419 Delta Air Lines 7 2026-06-09
DAL400 Delta Air Lines 7 2026-07-24
DAL450 Delta Air Lines 6 2026-05-23
DAL440 Delta Air Lines 6 2026-06-24
DAL359 Delta Air Lines 6 2026-07-18
DAL345 Delta Air Lines 6 2026-07-18
DAL311 - 6 2026-07-17
DAL663 Delta Air Lines 5 2026-07-25
DAL613 - 5 2026-06-16
DAL612 Delta Air Lines 5 2026-06-16
DAL486 Delta Air Lines 5 2026-05-19
DAL453 Delta Air Lines 5 2026-05-05
DAL435 - 5 2026-07-19

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 DAL465 LAX → HNL Jul 26, 21:15 UTCJul 26, 21:45 UTC30m
2026-07-26 DAL829 JFK → PHX Jul 26, 18:10 UTCJul 26, 19:35 UTC1h 25m
2026-07-26 DAL1318 MSP → EWR Jul 26, 14:35 UTCJul 26, 16:00 UTC1h 25m
2026-07-26 DAL1142 SLC → JFK Jul 26, 03:30 UTCJul 26, 05:00 UTC1h 30m
2026-07-26 DAL1142 SLC → JFK Jul 26, 03:25 UTCJul 26, 04:49 UTC1h 24m
2026-07-26 DAL1210 LAX → SFO Jul 26, 00:15 UTCJul 26, 01:40 UTC1h 25m
2026-07-25 DAL1210 LAX → SFO Jul 25, 21:15 UTCJul 25, 22:50 UTC1h 35m
2026-07-25 DAL663 ATL → SLC Jul 25, 16:14 UTCJul 25, 19:36 UTC3h 22m
2026-07-25 DAL663 ATL → SLC Jul 25, 16:15 UTCJul 25, 19:45 UTC3h 30m
2026-07-25 DAL923 ATL → SFO Jul 25, 12:25 UTCJul 25, 14:30 UTC2h 5m
2026-07-25 DAL1655 DEN → LGA Jul 25, 05:35 UTCJul 25, 10:35 UTC5h 0m
2026-07-24 DAL1655 DEN → LGA Jul 24, 21:35 UTCJul 25, 03:30 UTC5h 55m
2026-07-24 DAL400 ATL → EWR Jul 24, 14:25 UTCJul 24, 19:25 UTC5h 0m
2026-07-24 DAL400 ATL → EWR Jul 24, 14:24 UTCJul 24, 19:22 UTC4h 58m
2026-07-24 DAL2919 MCO → LGA Jul 24, 01:35 UTCJul 24, 07:25 UTC5h 50m
2026-07-23 DAL438 SEA → AUS Jul 23, 18:35 UTCJul 23, 23:20 UTC4h 45m
2026-07-23 DAL699 JFK → SEA Jul 23, 11:15 UTCJul 23, 16:35 UTC5h 20m
2026-07-23 DAL699 JFK → SEA Jul 23, 11:14 UTCJul 23, 16:47 UTC5h 33m
2026-07-22 DAL1845 JFK → STI Jul 22, 15:55 UTCJul 23, 06:00 UTC14h 5m
2026-07-22 DAL705 MCO → SEA Jul 22, 11:10 UTCJul 22, 11:20 UTC10m
2026-07-21 DAL423 ATL → SLC Jul 21, 19:40 UTCJul 21, 22:55 UTC3h 15m
2026-07-21 DAL875 LGA → ATL Jul 21, 14:50 UTCJul 21, 18:00 UTC3h 10m
2026-07-20 DAL663 ATL → SLC Jul 20, 16:10 UTCJul 20, 19:25 UTC3h 15m
2026-07-20 DAL2242 LAS → CVG Jul 20, 10:30 UTCJul 20, 12:33 UTC2h 3m
2026-07-20 DAL2242 LAS → CVG Jul 20, 10:30 UTCJul 20, 11:45 UTC1h 15m
2026-07-20 DAL9754 JFK → ATL Jul 20, 05:29 UTCJul 20, 07:37 UTC2h 8m
2026-07-20 DAL9754 JFK → ATL Jul 20, 05:30 UTCJul 20, 07:40 UTC2h 10m
2026-07-20 DAL2198 ATL → EWR Jul 20, 00:10 UTCJul 20, 03:10 UTC3h 0m
2026-07-19 DAL1651 MSP → LAX Jul 19, 19:15 UTCJul 19, 22:30 UTC3h 15m
2026-07-19 DAL792 - Jul 19, 13:30 UTCJul 19, 16:40 UTC3h 10m
2026-07-19 DAL435 - Jul 19, 07:10 UTCJul 19, 11:45 UTC4h 35m
2026-07-19 DAL435 LIH → LAX Jul 19, 06:46 UTCJul 19, 11:48 UTC5h 2m
2026-07-18 DAL345 BOS → SEA Jul 18, 23:15 UTCJul 19, 04:35 UTC5h 20m
2026-07-18 DAL2921 SLC → SEA Jul 18, 20:00 UTCJul 18, 21:35 UTC1h 35m
2026-07-18 DAL387 ATL → SLC Jul 18, 15:05 UTCJul 18, 18:20 UTC3h 15m
2026-07-18 DAL652 DEN → BOS Jul 18, 07:20 UTCJul 18, 11:30 UTC4h 10m
2026-07-18 DAL359 PSP → ATL Jul 18, 03:50 UTCJul 18, 04:45 UTC55m
2026-07-17 DAL359 PSP → ATL Jul 17, 23:20 UTCJul 17, 23:30 UTC10m
2026-07-17 DAL351 - Jul 17, 21:00 UTCJul 17, 21:25 UTC25m
2026-07-17 DAL351 SEA → HNL Jul 17, 15:46 UTCJul 17, 21:22 UTC5h 36m
2026-07-17 DAL351 - Jul 17, 15:49 UTCJul 17, 16:40 UTC50m
2026-07-17 DAL485 KOA → SEA Jul 17, 07:55 UTCJul 17, 13:20 UTC5h 25m
2026-07-17 DAL311 - Jul 17, 04:54 UTCJul 17, 04:59 UTC5m
2026-07-16 DAL311 - Jul 16, 23:55 UTCJul 17, 00:30 UTC35m
2026-07-16 DAL634 - Jul 16, 17:05 UTCJul 16, 21:05 UTC4h 0m
2026-07-16 DAL634 DTW → LAX Jul 16, 17:04 UTCJul 16, 21:02 UTC3h 58m
2026-07-16 DAL2845 - Jul 16, 13:30 UTCJul 16, 15:35 UTC2h 5m
2026-07-16 DAL2845 MCO → DTW Jul 16, 13:24 UTCJul 16, 15:31 UTC2h 7m
2026-07-16 DAL1513 BOS → MCO Jul 16, 00:31 UTCJul 16, 02:57 UTC2h 26m
2026-07-16 DAL1513 BOS → MCO Jul 16, 00:35 UTCJul 16, 03:05 UTC2h 30m

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 N510DE page for operator, model, and routing details .

Mode-S A661BF frequently asked

What is Mode-S code A661BF?
A661BF is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N510DE.
Where is Mode-S A661BF registered?
Mode-S code A661BF 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 A661BF broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A661BF, octal 51460677, decimal 10,903,999.
What flights does A661BF operate?
Mode-S A661BF has broadcast 20 distinct callsigns, including DAL1780, DAL506, DAL443, DAL422, DAL351.