ARL-SM (MiG21Bis)


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Jan 14, 2006
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This will explain the usage of ARL-SM on MiG21Bis fighter. It is primarily intended for those bought by former Yugoslavia but I guess it will also represent any active Bis on this planet. Stay focused while reading, this was translated on Serbian by military personel, and for this forum is translated again to English by me, so things won't be always in spirit of English language :-X. I haven't checked for spelling errors because my hamburgers will be fried if I don't leave computer right now....


Aparature ARL-SM is used for receiving and decoding commands received from control
centre used for aircraft guidance during mission. Aparature is turned on or off using
"lazur" switch located on the cockpit's right wall. Gudance commands are shown on
navigation and control instruments: UKL-2K, VDI-30, UISM-I and IPL-M. Brightness of
received commands is adjusted using "ark.ipl" situated on cockpit's right wall. Command row
situated on the left cockpit wall can be used for:

Radio data settings by turning "Volni" (Waves), "Shifr" (Code), "Raznosi" (separation) until
in pits of their protection coverages desired wave values from 10 to 20 are shown in two
rows, for example 1/8 represent the wave number 18.

Pre-settings of radio data and pre-setting signalization, after relevant lights are turned
on when "rucn" button is pressed (after desired Volni, Shifr and Raznosi values are

Automatic aparature pre-setting on new radio data when "avt" button is pressed, when
cooperation (vzaimodeistvie) command is issued.

adjusting light brightness using "ark" switch.

When ARL-SM aparature is turned on and radio data is selected - lights will signalize that
Volni, Shifr and Raznosi are selected.

Rhytmical blinking of command "I" or some other command on IPL-M will occur when ground
control station is working or when self test (KPA) aparature is turned on.

Course command is issued on UKL-2K related to current course. Fulfillment of course
commands is done by matching the course needle with triangualr index of current course and
during that vertical IPL needle needs to match the vertical line of the cross.

On UISM-I is given the required true airspeed.

Fulfillment of speed commands require that true airspeed needle matches triangular index
of commanded airspeed.

On VDI-30 commanded altitude needed during attack is shown (triangular index related to
altitude scale in thousands (m)).

Altitude commands are fulfilled by matching altimeters short needle with triangular index
of commanded altitude. After commanded altitude is reached horizontal IPL needle matches
horizontal line of the cross.

On IPL following commands can be shown:

<, I, >, F, 100, 60, 36, !, X.

When "<" shines - turn left is being signalized, "I" keep forward, ">" turn right -

informing the pilot about impending maneouver. Turn is being done only after course commands
start changing, adjusting angle of turn so that needle of commanded course is matching with
static UKL index and vertical IPL needle matches the vertical line of the cross.

Shining of "F" command is signal when quickly turning afterburner on is required, and is
followed by rhytmical 800hz sound signal. Once afterburner is on sound signal stops, but
"F" command is still shining. When F stops shining longer rhytmical 800hz sound signal
will appear and represents the command to turn off the afterburner. Once afterburner is off
sound signal stops. Sound commands to turn on or off afterburner are "." or "-" in
Morseus alphabet.

Shining of range command "100", "60", "36" will happen in moment of reaching the given
distance to assigned target and will continue untill next distance command begins to shine.
When "36" command is shining pilot will turn his radar on in search mode.

When distance between MiG21Bis and its target is 20km or smaller - distance info will be
shown on analogue instrument that measures distance.

When "!" signal is shining - it warns the pilot about change of target, or repeated guidance
on the same target. When "!" is on, all other commands will be turned off, and guidance
processing will be ceased as well (speed, altitude and heading will show last issued

When "!" goes off and rhytmical blinking one of "<", ">" "I" will signalize new guidance

Shining "X" command informs the pilot about guidance interruption. When "X" is on all other
IPL commands will be off. When ground control centre issues "fulfill orders" command - use
given (altitude, speed and course) IPL commands to reach the desired airbase.

Aparature ARL-SM provides semiautomatic transfer on new radio data that are pre-setted while
on ground which is done when "cooperation" command is issued and 800hz uninterrupted
sound signal will appear, shutting down all current commands and interrupting guidance
on target and on ARL-SM command row "avt" (automatic) light is shining. After that new
values regarding Volni, Shifr and Raznosi received from ground control will begin to shine

and sound signal stops. Meanwhile in the pits of protection covers old values will remain.

When one of "<", "I", ">" commands begins to shine rhytmicaly - that signalizes that

transfer to new ground control post is successfuly established and aircraft is receiving

commands from that new control post.

If command about change of target is received by voice via radio than for successful

transfer on new command post it is needed to manually set Volni, Shifr and Raznosi values

and to hit "rucn" (manual) button after that. If one of "<", "I" or ">" commands are shining

rhytmicaly transfer to new command post is successfuly done.

Flight while using ARL-SM:

After placing your ass in the seat make sure that correct Volni, Shifr and Raznosi are


After getting airborne establish the connection with ground control post and after one of

"<", "I" or ">" begins to shine rhytmicaly relax because your ARL-SM works normally.

After receiving command "Fulfill orders" match your flight on data received from ground

control post.

If "F" appears during guidance - turn the afterburner on and later follow afterburner


When "36" begins shining turn your radar on in search mode and search for desired target.

When "X" appears stop doing wha are you doing, report to command post and follow the

commands to reach desired airbase.

When flying in group flight leader follows the commands and others are following flight

leader. If leaders ARL-SM malfunctions next flight member with intact ARL-SM becomes flight

leader and informs ground control post about that.



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Jan 8, 2006
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Thanks Slick, I have seen only once the BIS cockpit. It happened on the airshow in Hungary, there was one serbian Mig-21bis, but I do not remember the LAZUR panel and it is also missing on my cockpit photos. Is it possible that the LAZUR panel could have been removed because of modernization? Is this panel you were talking about?

and the BIS from Kecskemet05.


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Jan 14, 2006
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Hi there :),

This on the picture is Bis from Deltas (note blue triangle under monster's head ;)) based in Belgrade (Batajnica). Can't say I ever looked well inside them because Fulcrums were around too and are much more interesting.

The panel from your picture generally looks like thing we are speaking about. If you haven't found anything like that, maybe you haven't searched hard enough or maybe it was removed. If you remember from I told you info is from "Izmene & dopune" which means ARL-SM isn't in the regular manual anymore. One Bis pilot said he has only handful of successful intercepts using ARL-SM. The biggest problem was that operator had no idea has his command went through or not, so we soon begun using radio together with ARL-SM. Now pilot had to watch displays and to focus on using radio as well. If either pilot or guy in command post were late in something or confused for a few moments it may disturb the planned pattern and whole thing looked clumsy.

Also during seventies we have tried to make SAMs and Fishbeds working with Swedish STRIL60, one our Bis has radar display removed and camera monitor and controls in place of it, some still remember red face of US military advisor when he saw we have turned some of their precious Sabre Dogs into recon planes...

I also have some procedures for ground control guy, but I have problem translating a few abbrevations and typing mathematic formulas in this fonts. If we overcome this you'll see that on this forum too...

Cheers ;D


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Apr 2, 2020
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Dear Slick, do you know exactly what was the data rate and the transmission pattern from a Vozdukh ground station to the ARL-SM Lazur on board the MiG-21? Was the transmission continuous, or in short bursts of data? How reliable the system was in practice?