BMS F-16C/D 4.34, Руководство по эксплуатации самолета

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T.O. BMS1F-16CM-1 BMS 4.34 Change 2.00
BMS 4.34 Dash 1
© Red Dog 2012-2019
Page: 156
One might wonder why these friendly aircraft are not answering the correct IFF mode 2 query.
This is where the studying of the briefing and more specifically the IFF policy will come in helpful.
The IFF policy stated that Mode 2 is aircraft dependant, so all aircraft in theatre have their own unique
Mode 2 code.
On the SCAN INTG page Mode 2 is set to our code (5654), so none of the interrogated aircraft are
able to answer with a valid code since our aircraft is the only one using that code. Knowing this it is
obvious why the Mode
2 queries can’t categorise the aircraft friendly. Fortunately correct responses in
Mode 1 and particularly the more secure Mode 4 allows the pilot to categorise them as friendly.
In LOS (Line of Sight) mode the IFF still scans the 60° elevation but restricts its scans in azimuth to
30° (approximately 15° either side) of the following reference:
•
If there is a target track: the target area
•
If there is no locked target:
o
the radar cursor in CRM.
o
the scan centre in ACM-SLEW.
o
the beam in ACM-BORE.
o
the aircraft nose line in any other case.
LOS interrogation is made according to the settings in the LOS INTG page, which may be different to
the interrogation settings on the SCAN INTG page.
Response symbols and scan mechanisation are the same as in SCAN mode. Notice OSB #16
highlighting LOS mode while interrogating Mode 4.
As you can see above the jamming contacts are not interrogated this time because they are outside
the interrogation cone roughly 15° either side of the ACQ cursor. On the other hand notice the friendly
Mode 4 response at 80 Nm. This one is inside the interrogation cone and provides a valid response,
since it’s friendly.
The IFF response is also displayed on the HSD (provided AIFF symbols are enabled on the HSD
CNTL page
– they are on by default).That is illustrated here for LOS but it is the same in SCAN mode.
IFF responses are always displayed on both the FCR and the HSD.
Mode 1, 2 & 3 interrogations more commonly provide invalid answers, illustrated by the yellow square.
Only part of the code may be valid and the system therefore categorises the contact as unknown.
Mode 4 is more reliable as it is encrypted and team-based, with only two keys available. Partial
responses are very rare; usually either the IFF responds correctly or it does not respond at all.
This is an important consideration as you shouldn’t expect a yellow square with a 4 inside. An enemy
aircraft interrogated in Mode 4 will simply not answer at all and might be categorised by lack of symbol
being displayed.