NOTAM released today at 0000Z. Plane departed at 1000Z. So the pilots WERE AWARE of a major threat.
V6158/14 NOTAMN
Q) URRV/QARLC/IV/NBO/E/000/530/4818N04023E095
A) URRV B) 1407170000 C) 1408312359 EST
E)
DUE TO COMBAT ACTIONS ON THE TERRITORY OF THE UKRAINE NEAR THE
STATE BORDER WITH THE RUSSIAN FEDERATION AND THE FACTS OF FIRING
FROM THE TERRITORY OF THE UKRAINE TOWARDS THE TERRITORY OF RUSSIAN
FEDERATION, TO ENSURE INTL FLT SAFETY,
ATS RTE SEGMENTS CLSD AS FLW:
A100 MIMRA - ROSTOV-NA-DONU VOR/DME (RND) ,
B145 KANON - ASMIL,
G247 MIMRA - BAGAYEVSKIY NDB (BA),
A87 TAMAK - SARNA,
A102 PENEG - NALEM,
A225 GUKOL - ODETA,
A712 TAMAK - SAMBEK NDB (SB),
B493 FASAD - ROSTOV-NA-DONU VOR/DME (RND),
B947 TAMAK - ROSTOV-NA-DONU VOR/DME (RND),
G118 LATRI - BAGAYEVSKIY NDB (BA),
G534 MIMRA - TOROS,
G904 FASAD - SUTAG,
R114 BAGAYEVSKIY NDB (BA)-NALEM.
SFC - FL320.
what this all means (for those who don't understand pilot jargon), certain airways (which are basically highways in the sky that all aircraft fly along) in and around the ukrainian-russia border, were forbidden from flying on from the surface (aka ground) upto and including 32,000 feet. MAS flight #17 was flying along a banned airway, but was at an altitude of 33,000 feet and not 32,000 feet, therefore wasn't breaking any regulations. The flight was also planned for 35,000 feet but ofcourse that could always change during flight.
Pilots took that risk.