SKYNET was built around electronic intelligence and as such, much of its campaign of technology during the War was built around its need for information, at all times, in all formats, on all campaign fronts.  The Model A9 aerial was slightly larger than the A4 but lighter armored and unarmed, relying on its altitude and speed to protect it, as well as other dedicated units in the area.  it was powered by the advanced second generation engines and though larger than the venerable A4, it was actually lighter due to the loss of much of the armor and weaponry.  The Advanced Warning And Ground Control Systems (AWAGCS) allowed SKYNET to coordinate all of its units in one particular zone down to an individual basis as well as provided the supercomputer with a high orbiting communications nexus point from which to route all of its commands to.  The Type 850T greatly increased and enhanced SKYNET's control in the combat zone.  SKYNET's instruction codes and datasets were sent up from Cheyenne Mountain to its orbital satellite assets, then beamed down to loitering 850T units in the theater.  The 850T units would then disseminate and coordinate the data as well as reroute all command and control systems as needed.   What one unit knew, all knew through the shared data link.  Data from one unit could be transmitted to another unit or all units in real time link that SKYNET monitored remotely.

The powerful radio and ECM / ECCM jammers carried by the A9 allowed it to "white out" the less technologically advanced equipment of the Resistance, reducing their communications capacity to almost nil.  The Resistance soon learned that the jamming did not affect line of sight infrared laser communication but such technology was in short supply and usually assigned only at the highest officer level for use in communicating between command groups operating together.  As such, SKYNET used the A9 to give it a tremendous advantage during the first decade and a half of the War, total communications control for its own forces and denial of information and communications for the Resistance.

Resistance forces referred to the A9 as the "Guppy," due to its odd bulbous shape, and Tech-Com personnel not only learned how to listen for the distinctive signals and spectrum emissions used when the A9s were operating overhead, but also how to bounce their own signals off the SKYNET unit and thus carrier-back their own C3 systems through the very technology that SKYNET was using against them.

Later in the War, Tech-Coms managed to configure a standard Stinger man portable surface to air missile of pre-War manufacture into a Surface to Air Homing Anti-Radiation Missile (SAHARM) format tuned to the unique emissions that the 850T produced, allowing a single soldier to carry a weapon capable of identifying, tracking, engaging and destroying one of SKYNET's most sophisticated units. 

After this, SKYNET had to be careful how it positioned its A9s, because they were no longer immune to attack or destruction by Resistance units.   Surface to Air Homing Anti-Radiation Missiles (SAHARMs) were bringing down the A9s at a steady (and unacceptable) rate.

A small technology war within the War itself took place between SKYNET and Connor's Tech-Com personnel.  The A9 was an incredibly valuable asset in any theater or operation but the humans had proven that they could learn to adapt (one of their most annoying characteristics) to SKYNET's advantages, and more annoyingly, to overcome those advantages in a time frame the computer could not logically understand.  SKYNET began employing limited stealth technology to its remaining A9 units, in an attempt to make them harder to detect but this also reduced their effectiveness by reducing their emissions and capacity to send / receive critical data streams.  The humans, invariably, learned how to bring even these improved A9 units down and as SKYNET sought new ways to protect its C3 structure, the humans were inventing new ways to exploit it in turn.

it was the coordinated loss of several A9s between 04252026AD and 09182027AD (a campaign planned and implemented by Connor himself) that ultimately turned the War in favor of the Resistance.  These A9s were assigned to and operating in a critical resource funnel and their loss came at a time when SKYNET's once impressive construction infrastructure was also being systematically attacked on multiple fronts resulting in a large percentage loss in the overall production capacity for new weapons and units.  it was on 09192027AD that the supercomputer realized that it could not build enough replacement A9 units to match the pace that the Resistance was knocking them out of the sky.

Just as the A9 had been a huge advantage to SKYNET in the early and mid years of the War, the loss of the A9 and the subsequent disruption of coordinated data and communications to the Machines became a human advantage and a turning point in the later years of the War.

MODEL A9 with high performance turbofan engine shown in flight position.
The sophisticated electronics are housed in the extended bulge
of the airframe forward of the control canards.