NMAC BTWN A LEAR JET; TURNING BASE LEG; AND A CESSNA 172 TFC WATCH ACFT TRANSIENT THROUGH THE TFC PATTERN.

Narrative

TEB IS AN ACCIDENT WAITING TO HAPPEN. THIS WK I HAVE HAD 2 NEAR MISSES IN THE PATTERN. THE MAIN PROB IS A MIX OF TOO MANY DIFFERENT TYPES OF ACFT (SMALL SINGLE ENG AND HELIS TO HVY JETS) IN TOO LITTLE AIRSPACE. THE EWR ARRS COMPRESS ALL TEB TFC TO BELOW 1500 FT AGL. COMBINE THIS WITH UNTIMELY TA'S AND A DIFFICULT VISUAL BACKGND FOR SPOTTING OTHER ACFT; AND AN ACCIDENT IS GOING TO HAPPEN. THIS MORNING WHILE MY FLT WAS ON A VISUAL APCH MANEUVERING FROM L DOWNWIND TO BASE (RWY 24) AT TEB; I HAD A NEAR MISS WITH A C172 (OR C182) DOING TFC WATCH NE OF THE ARPT. TWR ADVISED THE CESSNA AND MY FLT OF THE MUTUAL TFC. THE CESSNA CALLED US IN SIGHT AND WAS TOLD TO MAINTAIN THE VISUAL SEPARATION. I DOUBT THAT THE CESSNA HAD US IN SIGHT; BECAUSE APPROX 15 SECONDS AFTER HIS CALL; I GOT HIM IN SIGHT. AT THIS POINT MY FLT WAS 300 FT ABOVE AND APPROX 800 FT HORIZ AT HIS 8 O'CLOCK POS. HIS L WING WOULD HAVE PREVENTED VISUAL CONTACT. AT THIS TIME I TOOK OVER THE CTLS; FROM THE SIC/PF; FOR EVASIVE ACTION. THE NEAR MISS WAS APPROX 300 FT VERT AND 500 FT HORIZ. THIS WAS THE SECOND NEAR MISS AT TEB THIS WK FOR MY FLT. THE FIRST WAS WHILE DEPARTING RWY 19 ON THE DALTON DEP. IN THAT INCIDENT TWR DIDN'T ADVISE US OF ANY TFC UNTIL WE WERE AIRBORNE AT AN ALT OF 600 FT. AT THAT TIME HE ADVISED US OF A WBOUND HELI AT 600 FT AND AN EBOUND CESSNA (172/182) AT 1000 FT; BOTH IN OUR VICINITY. MY SIC/PF SAW THE CESSNA PASS 100 FT BELOW US. ON THE GND I CALLED THE LCL CTLR TO DISCUSS THE INCIDENT. HE SAID THAT BOTH ACFT WERE MAINTAINING THE VISUAL SEPARATION. IF THE CESSNA HAD US IN SIGHT IT IS DISTURBING TO THINK HE WOULD FLY WITHIN 100 FT OF A CLBING JET ON A HEAD-ON COURSE. BOTH OF THESE INCIDENTS OCCURRED DURING VERY HIGH COCKPIT WORKLOAD PERIODS.