A GA ACFT IN A CTLED FLT TOWARDS TERRAIN DURING A NIGHT OP.

Narrative

WE WERE RETURNING FROM A 4 HR TRAINING FLT (NIGHT; DUAL; XCOUNTRY) THE OBSERVER IN THE BACK CALLED OUT TFC BELOW US; APPARENTLY NOT MOVING IN RELATION TO US. BECAUSE WE WERE MANEUVERING FOR THE TFC PATTERN; I KNEW THAT ANY TFC BELOW US HAD TO BE CLOSE. I LOOKED BELOW AND TO THE R TO DETERMINE IF ANY EVASIVE ACTION NEEDED TO BE TAKEN. I OBSERVED RED AND GREEN LIGHTS AND STROBES. WHILE THE 3 OF US (MYSELF; STUDENT; OBSERVER) WERE PRE-OCCUPIED WITH THE TFC; WE HAD DSNDED BELOW TPA OF 6000 FT TO BELOW 5400 FT IN AN AREA WHERE THE TERRAIN IS ABOUT 5200 FT MSL. CONTRIBUTING TO THIS EVENT WERE THESE FACTORS: 1) I SHOULD HAVE DESIGNATED THE TASK OF FLYING THE AIRPLANE TO THE STUDENT WHILE I SEARCHED FOR TFC (I TOLD HIM TO MAINTAIN 7000 FT; BUT APPARENTLY HE MISREAD THE ALTIMETER). 2) I SHOULD HAVE MONITORED THE STUDENT'S PROGRESS A LITTLE CLOSER; ESPECIALLY IN LIGHT OF THE FACT THAT HE WAS TIRED; INEXPERIENCED; AND HADN'T FLOWN IN MANY MONTHS; AND 3) I HAVEN'T PRESSED HOME THE FACT THAT FLYING THE AIRPLANE IS THE MOST IMPORTANT TASK FOR THE PIC. IT TURNS OUT THAT THE FLASHING LIGHTS AND STROBES WERE FROM AN ARIZONA HWY PATROL CAR ON AN UNLIGHTED RURAL ROAD.