RIO seat: Quick look at the Countermeasures (AN/ALE-39 and LAU-138)

Are you confused about how many Chaffs and Flares you have aboard? Understandable, we’ve all been there. Therefore the intent of this article is clarifying a few things about the AN/ALE-39 and LAU-138 systems.
As usual, more details about these two devices are in the manual.


LAU-138

The LAU-138 is a chaff adapter and is the main cause of confusion when approaching the F-14B countermeasures system for the first time. The LAU-138 in fact is a rail that replaces the LAU-7 Sidewinder launch rail and contains 160 Chaffs. A total of two LAU-138 Sidewinders can mounted on station 1A and 8A (one per station). Additional AIM-9s do not use the LAU-138 rail but the original LAU-7. Therefore, in normal operations, we will be carrying 160×2=320 additional Chaffs.
Now, before you start jubilating and drooling thinking about the idea that no radar missile will ever kill you again, there’s a caveat: the LAU-138 indeed contains 160 Chaffs but that cartridge is smaller than the cartridges mounted in the AN/ALE-39 dispenser and in fact every activation releases 4 chaffs. This means that a single LAU-138 provides 160/4=40 Chaffs. Just to make everything even less intuitive, the LAU-138s are controlled together so two LAU-138 do not provide a total of 80 activations, but only 40.

AN/ALE-39

The original countermeasure dispenser set mounted on the F-14B is the AN/ALE-39. The AN/ALE-39 can be seen under the tail of the F-14, near the arresting hook and it looks like two boxes placed one in front of the other. Each box contains a maximum of 30 chaffs, flares or jammers, divided in two sections of 10 and 20 cartridges. Each section can contain different countermeasures and they are identified as R10, R20, L10, L20; R stands for Right and L for Left but in the Tomcat they are placed longitudinally: the Left is the Front dispenser and the Right is the Rear so it’s quite easy to remember.

rio4-countermeasures-kneeboard

The AN/ALE-39 should not be rearmed by the usual loadout panel (it can actually break the countermeasure system) but by asking the Ground Crew to load a different setting (F10 → Ground Crew → Set AN/ALE-39 Loadout). Since the Jammers are not implemented in DCS, the options available run from “60 Chaffs / 0 Flares” to “0 Chaffs / 60 Flares” in steps of 10.

Problem: what is set where? Since the AN/ALE-39 Programmer needs to know what is loaded in each of its sections and it does not recognize automatically the contents of the dispensers, how do we find out? The answer is in the Kneeboard.

The CMS column of the Kneeboard page shown in the image contains the settings required by AN/ALE-39 to operate correctly and also indicates if the LAU-138 is present. For instance, if you load Chaffs in R10 but select “F” for that slot in the AN/ALE-39 Programmer, every time you start a Flares dispense program you will actually drop a Chaff.
Selecting a combination of Chaffs and Flares in the Ground Crew menu is not enough though and at the moment we have to request an additional R&R in order to apply the new cartridges. You don’t have to change anything there if you don’t want, just open “Rearm & Refuel” and press OK (I imagine this will be changed at some point). Next step is pressing and holding the RESET switch in the AN/ALE-39 panel for at least 5 seconds and finally update the counters.

rio4-countermeasures-an-ale-39-lau-138
Chaffs dispensed by the AN/ALE-39 (top) and by a pair of LAU-138 (bottom).

The AN/ALE-39 releases only one Chaff whereas the LAU-138s dispense one set of mini-Chaffs from each rail. I was thinking about testing the effectiveness of 2xLAU-138 vs AN/ALE-39 but unfortunately every test I can think of are quite unreliable. Anyway, if you plan to do some test please let me know the results!

For the love of testing..

According to the manual:

“the R10 and R20 sections in the launcher are both connected to the R20 section and the R10 connected to the LAU-138s. [..] the R10 section type setting should always be set to C for chaff”

I was wondering about what impact the selection of different composition of Chaffs and Flares have on the AN/ALE-39 Programmer so I did some tests. I am not sure if the following values are set in stone or they change depending on the payload or other factors.

AN/ALE-39 ONLY

Loadout   AN/ALE-39 Programmer
Flares Chaffs L10 L20 R10 R20
50 10 C F F F
40 20 F C F F
30 30 F F C C
20 40 F C F C
10 50 F C C C

With no LAU-138 preset the programming is quite simple and the quantities are coherent with the expected number of Flares and Chaffs mounted.

AN/ALE-39 + 2xLAU-138

Loadout AN/ALE-39 Programmer
Flares Chaffs L10 L20 R10 R20
60 0 F F C F
50 10 C F C F
40 20 F C C F
30 30 F F C C
20 40 C F C C
10 50 F C C C

As you can see, the AN/ALE-39 Programming when LAU-138 are present is consistent with the manual because R10 is always set to Chaff.

Anyway, as long as you refer to the kneeboard to obtain the settings for the AN/ALE-39 you should not have any issue.

rio4-countermeasures-an-ale-39-programmer
AN/ALE-39 Set for 20 Flares / 40 Chaffs

Basic Programming

The AN/ALE-39 is not as advanced as the more recent AN/ALE-47 mounted on the F/A-18C.
The Default configuration is 0 Chaffs / 60 Flares and the LAU-138s provide additional 40 Chaffs, for a total of 40C /60F. Depending on the mission and tasking you may want to change the ratio of Chaffs and Flares contained into the AN/ALE-39 dispensers: CAS, CAP, BFM or BVR all favour different countermeasure types and programs. Make sure to plan ahead and adjust your settings accordingly!

Countermeasures release

Without going too much into the details, these are the three ways to dispense Chaffs and Flares. Check the manual for further information:

  • Pilot: the DLC releases countermeasures according to the status of the FLARE MODE switch (single Flare, single Chaff) when the flaps are up;
  • RIO: the two hat switches located on top of the DDD;
  • RIO: the AN/ALE-39 panel.

Flares

Flares in DCS can be used primarily in two ways:

  • Ground attack run: a single release every few seconds, in order to fool enemy IR threats. The shortest interval available is 2″ since there is no option for 1″ releases. Quantity-wise, the flares should cover your entire run, which can take from 10″ to 20″ depending on ordnance, ingress and egress and other factors. My default setting is 8/2, so a total of 8 flares dropped for 16″, but of course this setting is often adjusted to the mission itself.
  • Defeating an IR Threat: if an IR SAM or MANPAD is fired, a quick burst of Flares can be released in order to defeat the missile. Unfortunately the AN/ALR-39 does not provide any ad hoc program.
    Setting the Flare release to Multi so multiple flares can be dropped by the RIO at the same time is a solution, although it means that the pilot will controls Chaffs only. The alternative is “smashing” the Single Flare release button. Ideally, a burst of 5-7 flares within 2-3 seconds should defeat the threat. Easier said than done sometimes since the F-14 has no Missile Warning Receiver.

rio4-countermeasures-flares-salvo
Flares salvo vs MANPAD
rio4-countermeasures-flares-pre-emptive
Flares program vs MANPAD

Chaffs

Chaffs are used to defeat Radar-guided threats. They are controlled by the RIO and the Pilot if the FLARE MODE switch is not set to “Pilot” but they can also be slaved to the AN/ALR-67 Radar Warning Receiver by means of the PRW/MODE switch. On paper this is great but in reality that’s not really the case: what that function does is triggering a Chaff program as a threat is detected (SAM or Air-to-air missile); it also has a cooldown timer of 30″. In other words, it pops some chaffs when the SAM has just left the launcher and that’s pretty much it.
Radar SAMs and Air-to-Air missiles cannot be usually defeated by simply popping Chaffs so additional manoeuvres are required such as notching and turning to bleed off the limited energy of the missile. A combined use of manoeuvres and Chaffs is the best way to defeat a Radar guided Missile.

SAMs differs greatly depending on how old their technology is. Older SAMs can be defeated by releasing a bunch of Chaffs and appropriate manoeuvring. The default program or R/.5/1/2 (4-6 Chaffs, each every 0.5s, 1 repetition) works fine for defeating threats such as SA-2 and SA-3 as long as the pilot is also “Defending”.
More modern SAMs require much more effort on top of the release of a bigger “cloud” of Chaffs in a shorter period of time. This effect cannot be achieved with the AN/ALE-39 because the maximum amount of cartridges that can be dispensed at the same time is 6 (by setting B QTY to Random, 4-6 Chaffs are dispensed) and the minimum interval between salvos is 2″. Therefore we might need to activate the program manually more than once. On the other hand the pair of LAU-138s dispense twice the amount of Chaffs compared to the AN/ALE-39 but I haven’t tested if there are tangible benefits.

Merged!

In WVR (Within Visual Range) engagements everything happens much faster than at longer range (BVR). In this occasions the Auto Chaff can really help; granted, Radar missiles when merged are not as common as IR missiles, but an automated system that takes care of the delivery of Chaffs can definitely help.
Unfortunately the AN/ARL-39 cannot be used to create a joint Chaff-Flare profile. The idea of continuously dispense Flares to disrupt IR threats can be tempting but it makes us incredibly visible. Since the spotting system of DCS is not great, becoming less visible is very, very important. A shorter program such as 3/2 can be useful in case the threat is a position favourable to fire but be ready to dispense more Flares!

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