F-35 Broad Area Maritime Surveillance

I keep encountering a recurring belief among observers/commenters that the F-35 is some kind of miracle, broad area maritime surveillance (BAMS) platform and I don’t know where this comes from.  I suspect it’s a case of F-35 proponents latching on to anything they can to justify the aircraft.

This is an important claim because the F-35 in the BAMS role is claimed to be the foundation of the distributed lethality concept, the savior of carrier groups, the guidance system for attacking missiles, and the key to achieving total victory over China – all due to its claimed ability to leisurely cruise through enemy air/water space completely undetected while using its radar to search an entire hemisphere of the world with 100% detection of all enemy assets.  If that’s true, China stands absolutely no chance against us.  Is it true? 

Well, there is zero authoritative public domain information on the subject, that I’m aware of.  That makes drawing any definitive conclusions difficult, to say the least.  However, we have unlimited logic available to us so let’s apply some and see where it leads.

Detection Range.  The F-35 with its APG-81 radar is claimed to have nearly unlimited detection range with 100% detection and target identification.  Of course, this is ridiculous.  Without getting into the math, physics, and software of radar function, the simplistic truth is, ‘more power equals greater range’.  Thus, the larger, higher powered radar has better range and resolution than the smaller, lower powered one.  So, a fighter size radar, for example, has less range than an AWACS.

The only hint of range data for the APG-81 that I’m aware of is a claim of 150 km (90 miles) or so and that claim has occasionally been associated with a 1 sq.m. target which implies an aircraft target and aerial detection mode.  How applicable that is to the broad area maritime surface search we’re discussing is an open question.

Any manufacturer’s claim, which is, presumably, what the 90 mile claim is, is based on non-stealthy targets under ideal conditions, at best, or, far more likely, it’s just based on someone’s theoretical calculations.

Let’s consider the nature of the targets that are the subject of BAMS.  We’re looking for stealthy warships of various sizes.  China, for example, has their versions of the Burke although, visually, they appear to be a bit more stealthy.  They also have stealth missile boats (the Type 22 is a good example), corvettes, and frigates.  These stealth ships have reduced radar signatures.  The only data we have on ship stealth is vague statements that the ship (whichever ship) has a radar signature of a ‘fishing boat’.  Oddly, almost every ship of whatever size and degree of stealth seems to have the same claimed ‘fishing boat’ radar signature.  Obviously, the claim is very generic and utterly useless.  Still, it gives us some sort of very general idea of the reduction in radar signature.

What this means for our F-35 BAMS mission is that whatever the claimed range of the APG-81 radar might be, the effects of wave clutter, weather, and ship stealth combine to greatly reduce the actual detection range.

We also need to recognize the difference between detection and identification.  Let’s say we detect a ‘fishing boat’ at x-miles.  Okay, that’s nice but what is it?  Is it an actual fishing boat?  We’d hate to launch a maximum effort naval strike only to find out that the target was, indeed, a fishing boat!  That would be a lot of wasted missiles.  That means we have to identify the target in addition to detecting it.  That, in turn, means we have to get much closer – to the point where we can either visually identify it or our radar provides sufficient resolution that we can identify the signature.  So, our effective identification range is much shorter than our detection range which, we’ve already noted, is much shorter than the manufacturer’s claimed maximum range (which we don’t have for the APG-81 in surface mode).  So, our detection range is a mere fraction, and not a big one, of the maximum range.

Thus, the notion that a small, low power, fighter size radar can ‘see’ vast areas of ocean with 100% detection and identification is ludicrous. 

Logical Conclusion 1.  An F-35 APG-81 radar is going to provide a very limited view – the soda straw analogy.

Logical Conclusion 2.  Effective targeting is a two part challenge.  Detection is only half the problem and it’s the easy half.  Identification is the other half and requires that the F-35 approach the target much closer.  Thus, the suggestion that an F-35 can provide targeting from hundreds of miles away is utterly unrealistic.

Logical Conclusion 3.  Ship stealth will greatly reduce the detection/identification range.

Survivability.  In order for the F-35 to be an effective BAMS platform, it needs to be survivable long enough to find a target and track it to provide mid-course guidance for an attack.  That could, and likely will, require flying in enemy controlled air space for hours.  All the while, the enemy will be diligently searching the air space for just such activity.  Our F-35 will have to evade a multitude of all manner of sensors:  airborne patrols, ship radars, ESM, land radars, IRST, optical sensors, etc.  Yes, the F-35 is stealthy (from the front aspect – the sides and rear, not so much) but stealth isn’t magic.  Worse, the F-35 will be operating its own radar which further increases the chance of detection.  The odds on being able to loiter undetected in the vicinity of an enemy force in enemy air space are poor. 

Detection is a simple matter of statistics.  To illustrate, let’s say that a stealth aircraft has only a 1% chance of being detected in any given minute.  Hey, that’s great!  We have a 99% chance of not being detected.  Those are great odds, aren’t they?  However, over the course of an hour (sixty 1-minute intervals, each with a 1% chance of detection), that 1% chance of detection means a 46% chance of detection.  Oops.  Make it two hours and the chance of detection goes up to 71%.  Yikes.  Admittedly, this is a simplistic treatment of stealth and detection but it is, essentially, conceptually correct.  There is always a chance of detection and the longer the stealth aircraft loiters, the greater the chance of being found.  Thus, the idea that an F-35 can loiter and track targets and guide missiles is fundamentally suspect.  And, of course, the closer the F-35 loiters to the target, the greater the momentary odds of being detected.

Logical Conclusion 4.  Stealth aircraft WILL be found and the odds of being found increase with loiter time and proximity to the target.

Low Probability of Intercept (LPI) Radar.  The magic solution to detection and survivability, according to F-35 fanboys, is the fairy dust LPI radar.  F-35 proponents would have us believe that the LPI radar is undetectable while retaining maximum range and resolution.  Of course, this is simply untrue. 

LPI radars use a variety of methods to reduce the chance of the signal being intercepted (recognized in the background noise – the signal will always be intercepted).  These include frequency agility, pulse rate variation, etc. and, mainly, power reduction.  However, hand in hand with power reduction goes decreased detection range.

Make no mistake, LPI radars do, indeed, lower the chance of intercept (recognition) but do so at the expense of range and resolution.  Thus, our F-35, operating its APG-81 radar in LPI mode, will have the effective detection range (which we previously noted would be only a small fraction of the manufacturer’s claimed range) reduced even further.  This further reduction in detection range also means that the F-35 must get even closer to a target which, we previously noted, further decreases the F-35’s survivability.

Logical Conclusion 5.  LPI radar is not magic and will decrease detection range and survivability.

Area Search.  The key characteristic of BAMS is that it is a large area search function.  As such, the searching aircraft must, simplistically, pass back and forth repeatedly (a euphemism for whatever search pattern is employed) in order to effectively cover the desired area.  As we noted, given that detection range for targets of interest is going to be only a fraction of the claimed range, the searching aircraft will have to cover very small increments of the search area as opposed to sweeping vast areas in a single radar pulse, as F-35 proponents would have us believe.  This continual and extended back and forth searching, all the while with the radar broadcasting, is going to still further increase the chance of the F-35 being detected.  As noted in a Wiki article on LPI radar, a searching aircraft with LPI radar active will always be pointing its main lobe at some radar receiver. (1)

Having considered and applied all the preceding logic, it is logical to conclude that the F-35 cannot be an effective BAMS asset.  There is, in addition, one final bit of evidentiary logic that disproves the F-35 fanboy’s claims of effective BAMS and the simplicity of the logic is so self-evident that it needs no additional analysis:

Ultimate Logical Conclusion.  If all the claims for the F-35 broad area maritime surveillance capability were true, we’d have already eliminated AWACS, Triton, BAMS, E-2 Hawkeyes, etc. in favor of the F-35 with its APG-81 radar.

So, does the preceding mean that an F-35 is incapable of finding a target?  Of course not.  It just means that the F-35 is not a magical BAMS asset as so often claimed.  The F-35 is not the magical answer to the distributed lethality sensor problem.  The F-35 is not the magical answer to some notional sea control concept.  The F-35 is not a substitute for a carrier’s E-2 Hawkeye.

What can the F-35 do?  It can provide search over a limited area if we’re willing to risk the detection and loss of the aircraft.  Is it worth risking a $100M aircraft to do limited area search?  Well, that’s an operational question whose answer depends on what the potential benefits are in relation to the potential loss.

Where this can work best is when we have an idea where the target is and the search area – and risk - is, therefore, limited.  This is not as unlikely as it might sound.  Naval forces usually have at least a general idea of where the enemy is.  This was true throughout WWII and is true today.  A shared understanding of our own and the enemy’s strategies and objectives combined with various other sensor reports and intelligence are sufficient to offer general locations of enemy naval forces.  Thus, we do not need to search the entire ocean, we just need to search a moderately constrained area although prudence dictates sending search assets out in all directions just to be safe (the WWII carrier dawn 360 degree search by SBD Dauntlesses). 

We see then, that the F-35 is NOT a BAMS platform and would not be effective as such.  It can, however, be effective as a search/confirmation asset when we have a general idea of where to find enemy targets.

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(1)Wikipedia, “Low-probability-of-intercept radar”, retrieved 20-Dec-2019,

https://en.wikipedia.org/wiki/Low-probability-of-intercept_radar