Syrian Air Force capabilities of defense and fight.

Since the start of the Syrian Civil War, the Syrian Air Force had an vital role to keep goverment forces fighting, probably, after near 3 years of war, the SAF must have lost a lot of airplanes and personal, so, their readiness must not be good now.
But even now the SAF still conducts some missions, like the following:

- Air Strikes. Syrian Air Force is effective at conducting aerial bombardment and close air
support against opposition forces on the ground, as demonstrated by an apparent rise
in air-to-ground attacks since January 2013. The regime began to employ air assets in
the Summer of 2012 in order to repel rebel advance upon urban centers.
- Aerial Resupply. The Syrian regime is able to receive Iranian resupply by air, most likely
through the ad-Dumayr airfield East of Damascus and to Mazzeh military airfield near
the Lebanese border. Aerial resupply within Syria varies, though it has been the primary
mechanism for resupply to outposts that cannot be resupplied by ground
transportation.
- Aerial Delivery of CW. Air-dropped bombs are a traditional method to conduct
chemical attacks. The regime has the capacity to deliver chemical weapons inside
Syrian airspace. It is likely that they also have the requisite delivery mechanism.
- Air Defense. Syrian IADS is well-equipped, but it is old and poorly maintained. Against
close-range targets, Syrian IADS is still effective, as demonstrated by the shootdown of
Turkish reconnaissance aircraft in July 2012. Against long-range targets, Syrian IADS is
ineffective, as demonstrated by recent Israeli airstrikes near Damascus.

Stating that the SAF still have military capabilities and can wage war.
Since 2013 the number of air strikes have grown, as the following chart shows:

We can see a big increasing of the number of air strikes, one of the reasons was the lost of ground supply lines with the north in january, but in march and april this was retaken so the air strikes have gone down a little.



For the numbers, the following table show the number of the syrian airplanes in may 2013:

Maintenance, and Training
• A majority of SAF fixed wing aircraft are legacy
systems from the former Soviet inventory. These
MiG and SU series aircraft require significant spare
parts supply, maintenance man-hours, and training
to remain in a mission capable status.
• These aircraft require a high level of technical
expertise to fly and employ in combat. These skills
take a long time to acquire, and they are
perishable.
• The majority of SAF fixed wing airstrikes and
resupply missions are conducted with aircraft that
are easier to maintain and operate, specifically the
L-39 for strikes and the IL-76 for transport.
• Therefore, when estimating the equipment
capabilities of the SAF, it is important to recognize
that the Soviet-era MiG and SU series aircraft have
very low / nonexistent mission capable rates. In
order to neutralize the SAF, it is primarily necessary
to neutralize the L-39 and IL-76 fleet.

So we see that some of the regime capabilities are still functioning today, and the airstrikes may not be so easily sucessful as the western think.

sources:

http://www.understandingwar.org/sites/default/files/Updated%20Syrian%20Air%20Force%20and%20Air%20Defense%20Capabilities%20Brief_8May.pdf