NMAC BTWN AN LTT DSNDING OVER A VOR FOR A VISUAL APCH AND A SMA SEL TRAINING FLT HOLDING VFR OVER THE SAME VOR.

Narrative

I WAS HOLDING AT THE HGR VOR AT 4500 MSL AS PUBLISHED ON THE HGR VOR RWY 9 APCH. I ARRANGED WITH ZDC ON 134.15 TO DO 2 PRACTICE INST APCHS UNDER VFR AT HGR. I HAD BEEN ASSIGNED A DISCREET SQUAWK AND HAD RADAR CONTACT ESTABLISHED ABOUT 10 MIN EARLIER! I WAS INBOUND ON THE HOLDING RADIAL WHEN I WAS ADVISED OF A 'BAE 31' INBOUND FROM THE W LEAVING 5000 LNDG HGR; TFC RPTED TO BE AT MY 11 O'CLOCK POS. I RPTED TO ZDC THAT I WAS LOOKING BUT DID NOT SEE TFC. MY VISION WAS PARTIALLY BLOCKED BY MY STUDENT'S HOOD; USED FOR INST TRAINING. EVEN THOUGH I LEANED FORWARD TO LOOK AROUND HIS HOOD; I STILL COULD NOT SEE THE TFC. ABOUT 20 SECONDS LATER; I AGAIN LEANED FORWARD TO SCAN FOR TFC ON THE OTHER SIDE OF MY STUDENT WHEN I SAW THE (ACR). BAE 31 DSNDING TO OUR ALT ON A COLLISION COURSE FROM OUR L SIDE! I TOOK CTL OF THE AIRPLANE FROM MY STUDENT AND MADE A HARD R TURN TO AVOID A COLLISION COURSE FROM OUR L SIDE! I TOOK CTL OF THE AIRPLANE FROM MY STUDENT AND MADE A HARD R TURN TO AVOID A COLLISION WITH THE OTHER ACFT. I ADVISED THE CTLR OF THE SIT. HE THEN CONTACTED THE (ACR) AND ASKED IF HE SAW US PASS OFF HIS R SIDE. THEY SAID THEY NEVER SAW US. I FIND THE IFR TRAINING HOOD TO BE VERY LIMITING ON VISIBILITY OUT THE L SIDE OF THE ACFT. I FELT THE CTLR SHOULD HAVE TAKEN ACTION TO TURN; CLB OR DSND 1 OF THE ACFT! NO PLT HAD THE OTHER ACFT IN SIGHT!