A B737-200 ON CLB OUT AT 1000 FT DECLARED AN EMER AND DIVERTED DUE TO LOSS OF PRIMARY ALTIMETERS AND AIRSPEED INDICATORS. STANDBY INDICATORS OK.

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ON INITIAL CLB OUT OF ZZZ LOST BOTH CAPT AND FO'S PRIMARY ALTIMETERS AND AIRSPEED INDICATORS. EMER DECLARED; RETURNED TO ZZZ. USING STANDBY AIRSPEED AND ALTIMETER. POTENTIAL CONFLICT WITH ANOTHER ACFT ON APCH. WE OVERSHOT RWY 18R TFC ON RWY 18L. NO BREAKOUT REQUIRED. NOT SURE OF ACTUAL DISTANCE BTWN ACFT. LANDED UNEVENTFULLY. EMER WAS DECLARED TO ENSURE ALT PROTECTION FOR STANDBY OPS. COULD HAVE BEEN MUCH WORSE IF IMC CONDITIONS. CONDITIONS WERE SET TO BKN AT 4000 FT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE #2 AIR DATA COMPUTER SYSTEM HAD A LONG AND CHRONIC MAINT HISTORY OF MALFUNCTIONS. THE RPTR SAID THE SYSTEM WAS WORKED ON AGAIN OVERNIGHT; BUT EITHER DID NOT COMPLETE THE WORK OR WAS NOT FIXED. THE RPTR STATED MAINT RPTED THE #1 SYSTEM AIR DATA COMPUTER WAS USED FOR TROUBLESHOOTING THE #2 SYSTEM AND WAS NOT CONNECTED INTO THE #1 SYSTEM AFTER TROUBLESHOOTING. THE RPTR SAID THERE WERE NOT INOP FLAGS SHOWING ON THE #1 SYSTEM. CALLBACK FROM ACN 593167: THE RPTR STATED THE DUAL FAILURE WAS CAUSED BY THE #1 AIR DATA COMPUTER NOT BEING CONNECTED AND THE COMPLETE FAILURE OF #2 AIR DATA COMPUTER SYSTEM. THE RPTR SAID MAINT HAD WORKED THE #2 AIR DATA COMPUTER SYSTEM; BUT NOT FIXED THE PROB.