In message , Tony
Williams writes
This does not mean
that guns are useless for air-to-air work. They have a particular
value in modern 'policing' applications, as they enable warning shots
to be fired in front of suspect aircraft.

However, you have to load tracer for that: which reduces effectiveness
in combat.

They also provide an
economical way of engaging low-value targets such as unmanned
reconnaissance drones, transport and liaison aircraft, or
drug-smugglers.

"Economical" is extremely dependent on assumptions: while a burst of
cannon shells is cheaper than a missile, keeping your entire fighter
force trained and ready to be proficient in gun use is not cost-free.

In a 'hot' war they still have certain advantages in
close-quarter fighting, for example in 'picking off' an enemy
attacking a wingman, who may be too close for a safe missile shot.

Last time this occurred?

The
ability of modern fighters to adopt extreme attitudes, pointing well
away from the line of flight, significantly assists gun aiming in
dogfights.

Only if the extreme attitude can be sustained and controlled long enough
for a gun snapshot: meanwhile a less extreme diversion wastes less
energy yet still allows an off-boresight missile shot.

Cannon projectiles have a shorter flight time than a
missile, a significant advantage in a dogfight.

Can't miss fast enough to win: and it takes significantly longer to get
into guns parameters.

Finally, the gun provides a last-ditch capability if the missiles run
out,

If an infantryman runs out of ammunition, should he continue to close
with the enemy in hopes of getting into bayonet, buttstock, boots and
teeth range?

When you find yourself at a major disadvantage, it's rarely wise to
press on through the killing zone.

or are defeated by advanced countermeasures or simply by
circumstances.

The trouble is that gunsights require significant sensor input:
particularly if the aircraft is flying extreme manoeuvres to generate
snapshots. This means that an enemy able to deceive radar-guided
missiles is also generating miss distance for cannon rounds.

The 1991 Gulf War revealed the deficiencies of modern
IR-homing missiles when faced with trying to pick up a low-flying
target against a hot desert background (helicopters being in any case
difficult for IR seekers to lock on to from above). USAF A-10
aircraft achieved two helicopter kills with the GAU-8/A (using 275 and
550 rounds respectively) in one case when the IR missiles failed to
lock on.

550 rounds is more than many fighters carry, even when using less potent
Gatling guns. Is the problem "only guns can kill low-flying
helicopters", or "there's a need to improve capability against
low-flying helicopters"?

Furthermore, the performance of even the best missiles cannot
always be guaranteed, for various reasons. In Kosovo, a US fighter
engaging a Serbian plane needed to fire three AMRAAMs to bring it
down.

How many cannon rounds were fired, out of interest?

In other engagements in the late 1990s, USAF and USN fighters
fired a total of seven Sparrows, AMRAAMs, and Phoenix missiles against
Iraqi MiG-25s without scoring a single hit (although the Phoenix shots
were taken at extreme range).

Again, how many gun shots were fired?

The Iraqi aircraft were evading at the edges of the missile envelope:
what improvements to the US aircraft's gunnery systems would have
changed the outcome?

Whatever the reason, this results in missiles being used
up at a high rate, making it more likely that they will run out during
a sortie. A cannon will typically carry enough ammunition for several
engagements, usefully increasing combat persistence at a minimal cost
in weight and performance.

Trouble is, just because _you_ are out of missiles doesn't mean the
enemy will chivalrously cease fi and it's much easier for the enemy
to get you into missile parameters, than for you to lure an enemy into a
guns shot. (Especially when you're having to break off your approaches
to evade enemy AAMs)

One curious aspect to the use of AAMs in combat is that of the
approximately 1,000 kills achieved between 1958 and 1991, only a
handful were scored beyond visual range, which does raise questions
about the significance of the very long ranges of which some missiles
are capable.

Restrictive ROE accounts for a great deal (Vietnam): limited conflict
area (Middle East); and weapon availability (Falklands).

Also, define "visual range". The definition usually cited is "within
five miles", which is well outside guns range and only useful for
head-on Sidewinder shots: "long-range" missiles may struggle to close
five miles of seperation in a low-altitude, co-speed tailchase.

There is a continual battle between missile sensor and countermeasure
technology.

And the gun is not immune, since it requires sensor input for any but
the crudest shot.

In the future, stealth technology applied to aircraft may
considerably shorten target acquisition and combat ranges, putting
into question the worth of modern BVR (beyond visual range) AAMs. The
possible future use of anti-radar missile guidance as a way of
overcoming stealth characteristics may force fighters to make minimal
use of their own radars, further reducing acquisition and combat
distances.

And making guns use equally problematic, as snapshots become much more
demanding and gyro gunsights demand tracking shots.

Of course, modern guns are usually aimed by the plane's radar which
could also be jammed (although less easily than the much smaller and
less powerful missile seekers) but laser rangefinders could make an
acceptable alternative in providing fire control data.

Only for range: not for angular rate.

If planes
eventually become 'laser-proof' as well, the possibility presumably
exists of linking variable magnification optical sights to a computer
which would be able to analyse the image, identify the plane,
calculate its distance, speed and heading and provide gunsight aiming
information accordingly, all without emitting any signals.

If you can do all this and compute a gunnery solution, why can you not
fly a much larger guided warhead into the target from greater range than
a cannon will allow?

However, not all conflicts involve front-line opposition; in fact,
armed forces are now commonly engaged on police work, frequently
dealing with guerrilla forces. In these circumstances, rockets and
missiles may represent an inappropriate degree of destruction, with a
high risk of collateral damage. The RAF was embarrassed during
operations against insurgents in Sierra Leone in 2000 to find that
they had no suitable weapon for their gunless Harrier GR.7 aircraft to
attack small groups of rebels operating close to innocent civilians.

Given the lack of air opposition, why not use Sea Harriers with their
reliable, proven 30mm ADENs for the role? It seems more is being made of
the story than might actually exist.

Another advantage of using cannon was demonstrated in the invasion of
Afghanistan in 2002. During an intense infantry battle at Takur Ghar
in late May, in which US forces were ambushed and in considerable
danger, air support was called for. The AC-130 was not permitted to
intervene in daylight due to its vulnerability, so USAF fighters were
sent to help. For a part of the battle the Afghan combatants were too
close to the Americans for rockets or bombs to be used, so the
fighters – F-16s and even F-15s – went in strafing with their 20 mm
cannon, as did the Navy's F-14s and F/A-18s on other occasions.

And, curiously, the ground troops reported how the enemy refused to be
suppressed, neutralised or destroyed by those strafing passes: though
PGMs dropped carefully in "danger close" proved effective.

Even
RAF Tornadoes were reported to have carried out gun strafing runs on
at least one occasion. It may logically be argued that it is foolish
to risk an extremely expensive aircraft, with its expensively trained
pilot, to being lost due to very low-tech ground fire, but sometimes
the risk needs to be taken to save friendly lives."

I'm automatically wary of this variation of "If it saves the life of
even one small child..."

--
When you have to kill a man, it costs nothing to be polite.
W S Churchill

Paul J. Adam MainBoxatjrwlynch[dot]demon{dot}co(.)uk