BMS F-16C/D 4.34, Flight Manual

Page: 157 / 234

T.O. BMS1F-16CM-1 BMS 4.34 Change 2.00
BMS 4.34 Dash 1
© Red Dog 2012-2019
Page: 157
Yet as said in the introduction of this chapter, the lack of response
isn’t enough on its own to
categorise a contact as a bandit. It might very well be a friendly, who for whatever reason is not able to
answer Mode 4 queries. Reasons could include: battle damage, Mode 4 not active on the transponder
STAT page, aircraft not equipped with Mode 4 transponder capabilities, etc.
Now that we
mastered the IFF basics, let’s induce the rotation of code or active modes based on TIME
or POS events.
Remember that the IFF system is made of two parts: the transponder and the interrogator. The IFF
policy loaded in your DTC mostly impacts your transponder. IFF policy may define both the active
modes of the interrogator and the transponder, but if a code is set to change according to a TIME or
POS event it will only change in the transponder side of the IFF. The interrogator side of the IFF
changes are
left to the pilot’s discretion.
Pilots may elect to couple interrogator and transponder settings to avoid having to manually track any
changes due to TIME or POS events.
On both INTG DED pages (SCAN and LOS) is a setting labelled DCPL (9) by default. DCPL stands for
decoupled and signifies that the interrogator is decoupled from the transponder. That state can be
changed to CPL (coupled) mode by pressing ICP key 9 then ENTR.
Available options are DCPL (decoupled), ALL (all are coupled) and SOME (some modes are coupled).
Entering ICP key 9 and ENTR sets the relevant
interrogator mode (SCAN or LOS) to ALL by coupling all
interrogation modes to the transponder modes.
All codes will then be highlighted and will display the same
code as the transponder STAT page. Example right ALL
interrogator codes are highlighted meaning they are all
coupled with the transponder codes.
A further toggle of ICP key 9 and ENTR puts the relevant interrogator mode in DCPL again, where
codes from the interrogator might be different than codes from the transponder. In that case, all codes
will not be highlighted.
It is also possible to decouple one mode only. To do so couple them all first and then enter the code
you want to decouple. Say you want to decouple Mode 1,
which is currently set to 22 (same as the transponder), type
31 in the scratchpad and ENTR. The SCAN interrogator
Mode 2 will then be set to 31. Doing so it is no longer
coupled to the transponder M2 code (22) the code 31 un-
highlights and the CPL/DCPL status changes to SOME.
A colon appears next to M1 showing that this mode is
decoupled.
The example above was made in the SCAN interrogator page but is equally valid on the LOS
interrogator page. Both modes may be coupled or decoupled independently from one another.
IJAM (7) is IFF Jamming and is not implemented. It can be highlighted as eye-candy only.