sensors Mode-S transponder
A4FFB7
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N421DX · AIRBUS A-330-900 · operated by DELTA AIR LINES INC
- Hex
- A4FFB7
- Octal
- 51177667
- Decimal
- 10,813,367
- Country
- US
- Tail
- N421DX
- Type
- A339
- Flights observed
- 272
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 3h ago
Current position
Country allocation
The ICAO 24-bit address A4FFB7 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 |
|---|---|---|---|
| DAL17 | Delta Air Lines | 12 | 2026-06-23 |
| DAL16 | - | 11 | 2026-06-22 |
| DAL133 | - | 11 | 2026-06-27 |
| DAL157 | - | 9 | 2026-07-11 |
| DAL132 | - | 9 | 2026-06-27 |
| DAL66 | Delta Air Lines | 8 | 2026-06-07 |
| DAL241 | - | 8 | 2026-07-05 |
| DAL222 | - | 8 | 2026-07-04 |
| DAL215 | - | 8 | 2026-07-04 |
| DAL143 | - | 8 | 2026-06-28 |
| DAL224 | - | 7 | 2026-07-06 |
| DAL214 | Delta Air Lines | 7 | 2026-07-03 |
| DAL67 | Delta Air Lines | 6 | 2026-06-08 |
| DAL59 | - | 6 | 2026-06-19 |
| DAL58 | - | 6 | 2026-06-15 |
| DAL56 | - | 5 | 2026-07-07 |
| DAL273 | - | 5 | 2026-07-12 |
| DAL272 | - | 5 | 2026-07-12 |
| DAL243 | - | 5 | 2026-06-29 |
| DAL227 | - | 5 | 2026-07-09 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-14 | DAL212 | - | Jul 14, 01:10 UTC | Jul 14, 02:50 UTC | 1h 40m |
| 2026-07-13 | DAL203 | ATH → JFK | Jul 13, 07:25 UTC | Jul 13, 17:30 UTC | 10h 5m |
| 2026-07-12 | DAL202 | - | Jul 12, 19:30 UTC | Jul 13, 04:25 UTC | 8h 55m |
| 2026-07-12 | DAL202 | JFK → ATH | Jul 12, 19:26 UTC | Jul 13, 04:22 UTC | 8h 56m |
| 2026-07-12 | DAL273 | LIS → JFK | Jul 12, 09:40 UTC | Jul 12, 16:30 UTC | 6h 50m |
| 2026-07-12 | DAL272 | JFK → LIS | Jul 12, 01:20 UTC | Jul 12, 07:25 UTC | 6h 5m |
| 2026-07-11 | DAL157 | - | Jul 11, 11:45 UTC | Jul 11, 19:40 UTC | 7h 55m |
| 2026-07-11 | DAL157 | - | Jul 11, 03:45 UTC | Jul 11, 19:40 UTC | 15h 55m |
| 2026-07-10 | DAL157 | - | Jul 10, 21:50 UTC | Jul 11, 19:40 UTC | 21h 50m |
| 2026-07-10 | DAL156 | JFK → ACC | Jul 10, 21:12 UTC | Jul 11, 06:52 UTC | 9h 40m |
| 2026-07-10 | DAL156 | - | Jul 10, 21:15 UTC | Jul 11, 03:45 UTC | 6h 30m |
| 2026-07-10 | DAL226 | - | Jul 10, 00:35 UTC | Jul 10, 10:05 UTC | 9h 30m |
| 2026-07-09 | DAL227 | JFK → GRU | Jul 9, 02:39 UTC | Jul 9, 11:25 UTC | 8h 46m |
| 2026-07-09 | DAL227 | - | Jul 9, 02:40 UTC | Jul 9, 07:00 UTC | 4h 20m |
| 2026-07-08 | DAL4 | - | Jul 8, 16:05 UTC | Jul 8, 17:40 UTC | 1h 35m |
| 2026-07-08 | DAL4 | LHR → JFK | Jul 8, 16:05 UTC | Jul 8, 23:14 UTC | 7h 9m |
| 2026-07-08 | DAL10 | - | Jul 8, 04:15 UTC | Jul 8, 05:45 UTC | 1h 30m |
| 2026-07-08 | DAL10 | MSP → LHR | Jul 8, 04:13 UTC | Jul 8, 11:49 UTC | 7h 36m |
| 2026-07-07 | DAL165 | AMS → MSP | Jul 7, 13:35 UTC | Jul 7, 22:10 UTC | 8h 35m |
| 2026-07-07 | DAL56 | - | Jul 7, 01:15 UTC | Jul 7, 03:50 UTC | 2h 35m |
| 2026-07-07 | DAL56 | SLC → AMS | Jul 7, 01:14 UTC | Jul 7, 10:45 UTC | 9h 31m |
| 2026-07-06 | DAL221 | - | Jul 6, 12:25 UTC | Jul 6, 22:55 UTC | 10h 30m |
| 2026-07-06 | DAL221 | CDG → SLC | Jul 6, 12:24 UTC | Jul 6, 22:46 UTC | 10h 22m |
| 2026-07-06 | DAL224 | - | Jul 6, 03:15 UTC | Jul 6, 09:10 UTC | 5h 55m |
| 2026-07-05 | DAL241 | ATH → BOS | Jul 5, 10:30 UTC | Jul 5, 20:39 UTC | 10h 9m |
| 2026-07-05 | DAL241 | ATH → BOS | Jul 5, 10:35 UTC | Jul 5, 20:50 UTC | 10h 15m |
| 2026-07-04 | DAL222 | ATL → ATH | Jul 4, 21:35 UTC | Jul 5, 07:30 UTC | 9h 55m |
| 2026-07-04 | DAL215 | - | Jul 4, 08:25 UTC | Jul 4, 18:35 UTC | 10h 10m |
| 2026-07-03 | DAL214 | ATL → FCO | Jul 3, 20:50 UTC | Jul 4, 05:50 UTC | 9h 0m |
| 2026-07-03 | DAL109 | MAD → ATL | Jul 3, 08:05 UTC | Jul 3, 16:46 UTC | 8h 41m |
| 2026-07-03 | DAL109 | - | Jul 3, 08:05 UTC | Jul 3, 16:50 UTC | 8h 45m |
| 2026-07-02 | DAL62 | ATL → FCO | Jul 2, 22:10 UTC | Jul 3, 04:50 UTC | 6h 40m |
| 2026-07-02 | DAL125 | LIS → BOS | Jul 2, 12:49 UTC | Jul 2, 19:18 UTC | 6h 29m |
| 2026-07-02 | DAL125 | LIS → BOS | Jul 2, 12:50 UTC | Jul 2, 19:20 UTC | 6h 30m |
| 2026-07-02 | DAL124 | BOS → LIS | Jul 2, 04:15 UTC | Jul 2, 10:20 UTC | 6h 5m |
| 2026-07-01 | DAL241 | - | Jul 1, 11:00 UTC | Jul 1, 13:45 UTC | 2h 45m |
| 2026-07-01 | DAL241 | ATH → BOS | Jul 1, 10:58 UTC | Jul 1, 20:42 UTC | 9h 44m |
| 2026-06-30 | DAL222 | ATL → ATH | Jun 30, 21:40 UTC | Jul 1, 08:00 UTC | 10h 20m |
| 2026-06-30 | DAL222 | ATL → ATH | Jun 30, 21:36 UTC | Jul 1, 07:55 UTC | 10h 19m |
| 2026-06-30 | DAL109 | MAD → ATL | Jun 30, 08:10 UTC | Jun 30, 16:50 UTC | 8h 40m |
| 2026-06-29 | DAL62 | ATL → FCO | Jun 29, 21:50 UTC | Jun 30, 04:10 UTC | 6h 21m |
| 2026-06-29 | DAL243 | AMS → BOS | Jun 29, 09:46 UTC | Jun 29, 16:48 UTC | 7h 2m |
| 2026-06-29 | DAL243 | - | Jun 29, 09:50 UTC | Jun 29, 11:29 UTC | 1h 40m |
| 2026-06-28 | DAL142 | SEA → AMS | Jun 28, 21:28 UTC | Jun 29, 06:45 UTC | 9h 17m |
| 2026-06-28 | DAL142 | SEA → AMS | Jun 28, 21:30 UTC | Jun 28, 23:29 UTC | 2h 0m |
| 2026-06-28 | DAL143 | AMS → SEA | Jun 28, 08:39 UTC | Jun 28, 17:44 UTC | 9h 5m |
| 2026-06-28 | DAL143 | AMS → SEA | Jun 28, 08:35 UTC | Jun 28, 17:43 UTC | 9h 8m |
| 2026-06-27 | DAL132 | - | Jun 27, 20:34 UTC | Jun 27, 21:44 UTC | 1h 10m |
| 2026-06-27 | DAL132 | DTW → AMS | Jun 27, 20:30 UTC | Jun 28, 03:42 UTC | 7h 12m |
| 2026-06-27 | DAL133 | - | Jun 27, 07:39 UTC | Jun 27, 07:45 UTC | 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 N421DX page for operator, model, and routing details .