How do pilots detect lock-ons?

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henri51
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How do pilots detect lock-ons?

Post by henri51 »

This has no practical implication for the game, but I am just curious.

I know that when a missile locks on to one's plane, there is a distinctive noise to warn the pilot. My question is how do the sensors 'know" that it is one's specific airplane that is locked on (if it does know)?

Consider the Air War Tutorial Scenario, where one has put up say 6 F-14s to sweep the sky ahead of a land attack. There might be 4 or 5 enemy missiles in the air, some from SAM sites and some from enemy planes. Some might be locked in and some not.

Now I suppose that aircraft sensors detect a lock-on by a change in frequency when the radar switches from say ground radar tracking to missile tracking. But how do the sensors detect that it is MY specific airplane that has been locked on? Or if a single plane is locked on, do ALL the aircraft within the enemy cone start warning that there is a lock-on? If so, that can be a source of much confusion ("Lemme see, we have 6 planes in the air, so there is only one chance in 6 that it is me...however, I am closer than 3 other guys to the target, so the probability may be one in three...or is that one in two?..."). I don't know about you, but if I were a pilot preparing to drop a pinpoint bomb attack and I got a warning that a missile had locked onto my butt, my first priority would be to get rid of that missile!

So two questions: Does each aircraft "know" if it is the one locked on? 2) What is the standard procedure whether the question is yes or no?

I can think of a number of possible answers, all of which could be wrong: 1) Pay no attention and keep doing the mission; 2) Stat praying; 3) forget about the mission and save your butt; 4) Drop chaff and decoys and remember that the commander told you that they are 100% effective;5) Bail out.
Rudd
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RE: How do pilots detect lock-ons?

Post by Rudd »

quick answer: RWR http://en.wikipedia.org/wiki/Radar_warning_receiver
someone with more knowledge can explain further
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jomni
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RE: How do pilots detect lock-ons?

Post by jomni »

Warnings are always for "MY" plane. It won't know who's locking the other planes.

Standard procedure is to give priority to losing the lock first. Evasive maneuvers coupled with countermeasures.

Take note that it is harder to know if you are locked by heat seakers because those are passive sensors. They are usually detected visually.
JCR
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RE: How do pilots detect lock-ons?

Post by JCR »

If this question regards real life:

In the old days, a semi-active or beam riding SAM or AAM would need a radar to "paint" the target.
A RWR would detect that increased radiation on the target plane and transmit warnings to the pilot.
In regards to the SA-2, US radar warning recievers could detect the guidance signals to the missile and give a LAUNCH warning as well, but normally you'd just know that you're targeted, not wether a missile was actually launched, except if you saw it launch or approaching you.
A active Radar missile could only be detected visually or as soon as the missile itself switches on its radar.
Before the advent of 360 degree countermeasures in current fighter planes, there was no way but Mk 1 Eyeball to warn the pilot of a IR guided missile being launched.
In very modern fighters like F-22, F-35 or Eurofighter, 360 degree scanners scan for the IR plume of a missile launch and short range radar plots the approaching missile and recommends evasive maneuvers to the pilot
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MR_BURNS2
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RE: How do pilots detect lock-ons?

Post by MR_BURNS2 »

This may answer some of your questions:

http://www.ausairpower.net/TE-RWR-ECM.html
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smudge56
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RE: How do pilots detect lock-ons?

Post by smudge56 »

Very interesting.
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henri51
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RE: How do pilots detect lock-ons?

Post by henri51 »

Thanks for all the info, but none of it answers my question, which was perhaps not enough clearly stated: when there are multiple aircraft close to each other, how does a pilot (i.e. his sensors) know that it is not HIS aircraft that has been locked on by an enemy radar-guided missile? (For this purpose forget about heat-seeking missiles).

I would guess that in the "painting" phase where say a ground radar is looking for targets, ALL of the aircraft are getting the radar warning. But once a missile locks in to ONE aircraft, how do the other aircraft nearby "know" that they are not the ones targeted by the missile?

The only answer I can think of is that missile radar tracking systems have a beam that is so narrow that it is rare that two aircraft will be within the beam, i.e. only one aircraft is getting the lock-on signal. Is this the case? Jomni says that only the aircraft actually locked on gets the warning, and I assume that this is the case.
JCR
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RE: How do pilots detect lock-ons?

Post by JCR »

The illumination radar beam has a higher pulse repetition frequency (PRF) than normal search beams.
In ground based systems, this is often done by a seperate radar, in a fighter aircraft, the radar locks on a single target and can't search anymore as long as it illuminates.
StellarRat
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RE: How do pilots detect lock-ons?

Post by StellarRat »

It's basically a REALLY fancy radar detector like you'd have in your car.

Interesting side story: Some of the old timers in my ROTC class were helicoptor pilots in Vietnam. They said that if NVA radar directed AA (something they were terrified of, BTW) locked on they could hear a tone coming over their FM radio headsets. From the jist of the conversation, it sounded like that was just an accidental "feature" of they radios. They were not intended to detect radar. However, any high powered signal can interfere with a lot of off spectrum radio equipment untentionally and I think that's what was happening in this case. I don't know if the story is true or not, but it certainly could be. If anyone has more knowledge of this please share it.
Tomcat84
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RE: How do pilots detect lock-ons?

Post by Tomcat84 »

Basic idea: it depends on the beamwidth of the targeting system and whether or not you are both in that beam. Inside: you both think you're the target. Only one in the beam, then the other knows it's not him.
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henri51
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RE: How do pilots detect lock-ons?

Post by henri51 »

ORIGINAL: Tomcat84

Basic idea: it depends on the beamwidth of the targeting system and whether or not you are both in that beam. Inside: you both think you're the target. Only one in the beam, then the other knows it's not him.

Thanks Tomcat, that's what I thought. But since a diffraction-limited beam has an angular width of lambda/D where lambda is the wavelength and D is the diameter of the emitter, a one-cm radar beam from a 10 cm diameter emitter (say in a missile head)would have a beam coverage of 100 m at a distance of 1 km and of 1 km at a distance of 10 km, so it seems to me that there is a fair chance of two aircraft being inside the radar signals. Of course if both the painting and the guiding signals are coming from a 2 m antenna on the ground, then the radar beam width is very small (20 times smaller than in the above).
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RE: How do pilots detect lock-ons?

Post by bsq »

ORIGINAL: henri51
ORIGINAL: Tomcat84

Basic idea: it depends on the beamwidth of the targeting system and whether or not you are both in that beam. Inside: you both think you're the target. Only one in the beam, then the other knows it's not him.

Thanks Tomcat, that's what I thought. But since a diffraction-limited beam has an angular width of lambda/D where lambda is the wavelength and D is the diameter of the emitter, a one-cm radar beam from a 10 cm diameter emitter (say in a missile head)would have a beam coverage of 100 m at a distance of 1 km and of 1 km at a distance of 10 km, so it seems to me that there is a fair chance of two aircraft being inside the radar signals. Of course if both the painting and the guiding signals are coming from a 2 m antenna on the ground, then the radar beam width is very small (20 times smaller than in the above).
1 in 60 rule to all intents and purposes. Indeed you likely will not know, unless the tracking/locked emission exceeds a certain received power level. Even then it will only tell you that you may be the target. Don't be fooled by beamwidth though, because modern RWR systems will pick up side lobes, so the beamwidth is only relevant to the tracking radar and less sensitive RWR systems

The tracking radar itself uses tracking gates and circuits, so it knows which return is the target (all things being equal that is - no ECM)
bsq
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RE: How do pilots detect lock-ons?

Post by bsq »

ORIGINAL: JCR

The illumination radar beam has a higher pulse repetition frequency (PRF) than normal search beams.
In ground based systems, this is often done by a seperate radar, in a fighter aircraft, the radar locks on a single target and can't search anymore as long as it illuminates.
Only true for some systems. Some employ Track While Scan, some vary the waveform to provide different functions in different parts of a running scan. Newer airborne intercept radars do not need to lock on to a single target, being able to provide tracking on several targets and guide missiles to some of these.

There are several guidance methods and systems all of which could fool an RWR or prevent it from determining whether a true lock on has been achieved.
Tomcat84
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RE: How do pilots detect lock-ons?

Post by Tomcat84 »

ORIGINAL: bsq
Don't be fooled by beamwidth though, because modern RWR systems will pick up side lobes, so the beamwidth is only relevant to the tracking radar and less sensitive RWR systems

My RWR probably isn't modern enough then lol

Or it uses other methods. I don't know too much of all the technical stuff anyway haha
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acui
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RE: How do pilots detect lock-ons?

Post by acui »

Based on my studies. A modern RWR system will have multiple antennas. The RWR system can identify the type and working mode of a radar by the signal it received.

The rest is my guess. Because the characteristics of a known-type radar is also known (has already been stored in the RWR system) and the RWR has the signal strength from different antennas. The RWR can then calculate that whether or not it is at the center of the beam, thus knows if it is the locked target of a tracking radar.

I am from China. So please forgive me for my poor English[:)]
smudge56
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RE: How do pilots detect lock-ons?

Post by smudge56 »

No you did very well.
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bsq
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RE: How do pilots detect lock-ons?

Post by bsq »

ORIGINAL: acui

Based on my studies. A modern RWR system will have multiple antennas. The RWR system can identify the type and working mode of a radar by the signal it received.

The rest is my guess. Because the characteristics of a known-type radar is also known (has already been stored in the RWR system) and the RWR has the signal strength from different antennas. The RWR can then calculate that whether or not it is at the center of the beam, thus knows if it is the locked target of a tracking radar.

I am from China. So please forgive me for my poor English[:)]
This is how it determines AOA (Angle of Arrival) (where its coming from). It's a straight received power measurement (weighted for AOA) that determines relative strength of the signal and therefore whether it is assessed to be of sufficient power to be 'in range'.
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RE: How do pilots detect lock-ons?

Post by thewood1 »

Because the plane is moving, can a modern RWR also use that movement to determine location at all?
bsq
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RE: How do pilots detect lock-ons?

Post by bsq »

1st fix is using AOA and power to show rough location, then subsequent ones are going to be AOA based with cross fixing
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