The plane crash could have been accidental, caused by pilot error or mechanical failure. It could have been caused by Syrian air defenses, with or without Damascus' approval or knowledge. At this stage, it is unclear.
The Turkish air force flies three models of the F-4: The F-4E Phantom II that serves as a multirole fighter, the F-4E 2020 Phantom II that also serves as a multirole fighter and the RF-4E Phantom II that does reconnaissance and surveillance. The downed plane, assumed to be an F-4E 2020 or an RF-4E reconnaissance plane, took off from the Malatya base in Turkey.
Turkey likely has been conducting both routine patrols and reconnaissance missions, probably very close to Syrian airspace and perhaps has penetrated that airspace regularly. The F-4 could have veered off course or done something unusual, prompting the Syrian air defense response (although this is not a given, considering the amount of air activity likely occurring around Syria for months).
Syria certainly has been thinking very hard about air defense in the last year, and its forces are likely to be on alert as regime resources permit. Syrian forces could have thought they perceived something unusual about the plane and reacted aggressively at the individual battery level. Syria's most effective and newest air defense hardware is also short- and medium-range. Older SA-5 surface-to air-missiles would engage at the longest ranges — but if the Turkish plane was caught off guard, slow to react or subjected to a salvo, it might not have been able to evade even older Syrian hardware.
Erdogan's meeting with the National Security Council suggests that the incident was more than just a training accident. Turkey is already on alert for signs of Iranian and Syrian attempts to use factions of the Kurdistan Workers' Party to undermine Turkish security. This crash adds to these tensions.
The incident comes only one day after the New York Times reported that CIA operatives were in Turkey and helping to funnel weapons to Syrian rebels. The Turkish government denied the report. However, Ankara has been turning a blind eye to the rebels' operations and providing camps to the refugees who have poured into the country. Moreover, Ankara has called repeatedly for Syrian President Bashar al Assad to step down.
Turkey does not want an open conflict with Syria and does not want to militarily intervene there. Damascus does not want a war with Turkey either. The shooting down of a Turkish plane, however, by Syrian air defenses could cause both sides to shift military postures and create more possibilities for hostile engagements even though neither wants them.
So far, Erdogan does not appear to be building the case for follow-on military action. In a news conference, Erdogan made a vague statement, claiming he had no information in hand about the status of the pilots but confirming that a rescue mission is under way. Erdogan said he would make another announcement after discussing the details in the emergency meeting with the National Security Council.
Many details about the plane's downing remain sketchy and unconfirmed. The entire situation could have been a mistake, occurring without Ankara's or Damascus' permission or knowledge. Both sides could have contributed to the incident and escalated tensions. However, the incident could have been entirely unintentional, prompting reactions instead of deliberately chosen and executed actions.
The most important aspect of the plane's downing at this point is not exactly what happened but whether this is an isolated incident or the start of a more sustained, substantive shift in Turkey's military posture toward Syria. What happens in the next 24 hours along the Turkish border will give crucial clues.