Here's the METARs from around the time of the accident (approx. 1915Z). He could have been IMC at vectoring altitude.
Code:
KSEE 111955Z 21011KT 10SM BKN030 20/13 A2978
Code:
KSEE 111855Z 20012G17KT 10SM BKN027 19/13 A2980
KMYF 111953Z 18013KT 9SM SCT023 OVC029 19/13 A2977 RMK AO2 SLP078 T01940128
Code:
KMYF 111853Z 18010KT 10SM BKN017 OVC028 19/14 A2980 RMK AO2 SLP086 T01940139