How do I check a Mode S address against the aircraft register?

What are you looking up?

A Mode S address is an aircraft identification code used by its equipment. In this lookup, use the six-character code shown beside MODE S, including any starting zeros. It is different from the four-digit Mode 3/A squawk, the track number and the callsign.

Look up a track’s code

1. Select the track and open Flight Information. Find MODE S if that field is present. Not every contact has a Mode S address to look up.
2. Open ASMA and type CALL MODESCHECK followed by a space and the displayed code. For example, CALL MODESCHECK 4000A3 shows the format; use your track’s actual value.
3. Choose SEND. Select the ATC filter if the response is hidden. You do not need to open a controller line for this lookup.
4. Read MODE S CHECK and confirm the queried address matches. If a record is found, compare registration, aircraft type, operator and country with the track’s other information.

Browse the Aircraft Register panel

1. Find the minimised Aircraft Register bar in the game interface. Close the Escape menu if it is hiding the interface, then select the bar’s □ restore button.
2. Check Search: before reading the rows. On opening, the panel can fill this field from a hooked contact’s registration or Mode S address. If several contacts are hooked, confirm the search belongs to the one you mean. When you select another contact on the radar map while the register is expanded, check Search: again: its registration or Mode S address can replace your search. If no usable registration or address is available, the old text can remain. Replace it with the address you mean before reading the results.
3. To look up the displayed MODE S yourself, replace the search text with the complete six-character address. Keep leading zeros. Search also accepts registration, type code, aircraft name, operator, country, category or radio callsign, so partial text may match several records.
4. Read REG, MODE S, TYPE, AIRCRAFT, OPERATOR and COUNTRY together. REG is the registration; TYPE is the aircraft type code. Confirm the full Mode S address rather than accepting the first partial match.
5. Select a record row to show its available details below the list. Select that same row again to clear the row selection.
6. To remove a filter, delete the text in Search. This panel does not use the flight-plan list’s CLEAR and REFRESH buttons. No matching records is different from Loading register....

To tuck the register away, minimise it using its title-bar button. Restore it with □ on the small bar. This panel has no close button; use the panel layout controls if its position is awkward.

Read the detail strip

The strip can show MSN (the aircraft’s serial number), Year, Max Pax, Typical Pax, Cat (category) and R/T (radio callsign), plus type-reference weight, cruise speed, ceiling and range. Pax means passengers: maximum or typical figures are not a live passenger count. A missing detail is not a measured zero. Use the specification guide to understand the performance values. These catalogue details do not show this flight’s remaining fuel or current speed.

Worked example: five fields, one register entry

In the game’s catalogue, 4025BA is the Mode S address, G-BEOL is the registration, SC7T is the type code for Shorts Skyvan, Invicta Aviation is the listed 1998 operator, and Invicta is its radio callsign entry. These fields describe different things; none is the track number. Search 4025BA to find this record, then compare REG, TYPE and OPERATOR. This register example does not show whether the aircraft is currently flying in your session. Use the live track data and ATC information to investigate a selected contact.

What each result means

A match is one piece of evidence

Compare the result with Flight Information, the ATC reply and the aircraft’s observed movement. Use the identity-mismatch guide when those disagree. The lookup itself does not change the track’s identity.

Real world: what the register can tell you

The ICAO 24-bit aircraft address is allocated to an aircraft for uses including Mode S transponders. It is separate from the aircraft type designator. An allocated address does not prove that the aircraft has equipment fitted to use it. Its register explains the real-world fields; Air Defender uses its own period database.

Panel search or ASMA command?

The panel lets you browse records and inspect details. CALL MODESCHECK returns a message for the address you typed, which you can retain alongside the other ASMA responses. In both routes, compare the returned address and registration with the selected contact. A prefilled search, row selection or successful lookup does not issue an aircraft order or change its identity.

Narrow the search without losing the contact

Search checks your complete text as one phrase in each supported field and ignores upper/lower case. It does not combine separate filters: typing a type code followed by a country will not mean “this type AND this country”. Search one useful value first, then compare the other columns. The count beside Search is matching records / all records, not aircraft currently flying. Use the list’s vertical scroll bar to inspect more rows.

Try a register lookup

1. Select a contact that shows MODE S in Flight Information and note its full address.
2. Find that same address using Search: or CALL MODESCHECK in ASMA. Confirm the complete address rather than just the aircraft name.
3. Compare REG, TYPE and OPERATOR with the contact’s other information. Read the mismatch guide if they disagree; a mismatch still needs investigation.
4. Clear Search and look up a different record. Check that the selected row and detail strip refer to the same aircraft. If the details look inconsistent, use the ASMA address lookup as a separate check and record the problem.

When the radio name differs from the track label

BAW436 can appear as SPEEDBIRD 436 under RT Callsign. They are two forms of the same flight name. Use the civilian callsign examples and checks to distinguish the flight name, registration, Mode S address and track serial.