L39 PLT WAS OPERATING AS CHASE PLANE FOR A CERTIFICATION TEST FLT. WHEN A MAINT PROBLEM DEVELOPED; FORMATION INTEGRITY WAS LOST WHEN THE CHASE PLANE DID NOT DESCEND AS THE LEAD ACFT DESCENDED.

Narrative

DURING THE RETURN FROM AN ENGINEERING CERTIFICATION FLT TEST WITH A TEST PLT ON BOARD; THE CHASE ACFT EXPERIENCED A RED PRESSURE WARNING. THE WARNING WAS RPTED TO THE LEAD ACFT BUT NOT AS AN EMER AND TO CONTINUE A NORMAL DSCNT TO THE RWY. TRACON CLRED THE FLT TO 11000 FT ON HDG 045 DEGS. THE CHASE PLT DID NOT INFORM THE LEAD PLT THAT HE HAD SEPARATED AND REMAINED AT 15000 FT MSL. THE CHASE PLT WAS SUFFICIENTLY DISTR DURING THE HEADS-DOWN TROUBLESHOOTING TO LOSE SITUATIONAL AWARENESS AND LOSE SIGHT OF THE LEAD ACFT. THE CHASE PLT DETERMINED THAT REMAINING AT 15000 FT MSL WAS PRUDENT UNTIL CONDITION OF ACFT WAS DETERMINED AND RE-ACQUIRED VISUAL OF THE LEAD ACFT BEFORE DSNDING. THE FLT WAS CLRED TO 10000 FT. AFTER THE FLT WAS LEVEL AT 10000 FT; THE CHASE PLT RPTED THAT HE LOST SIGHT OF THE LEAD ACFT AND RPTED THAT HE WAS ABOVE THE LEAD ACFT. WHEN ASKED WHAT ALT; THE CHASE PLT RPTED THAT HE WAS STILL AT 15000 FT MSL. THE FLT CREW OF THE LEAD ACFT SEARCHED AND ACQUIRED THE CHASE AIRPLANE AT 12 O'CLOCK POS AND HIGH. THE CHASE ACFT WAS INSTRUCTED TO DSND TO 10000 FT FOR THE REJOIN. THE CHASE PLT REFUSED AND STAYED AT 15000 FT MSL BUT FOLLOWED THE VECTORS PROVIDED BY TRACON. THE FLT WAS CLRED FOR A VISUAL TO THE RWY AND BOTH ACFT STARTED TO DSND. THE CHASE ACFT ACCELERATED AWAY FROM THE LEAD ACFT AND WAS AHEAD OF THE LEAD ACFT BY 3-5 NM AS RPTED BY TRACON AND EVENTUALLY BEYOND VISUAL RANGE OF THE LEAD ACFT'S FLT CREW. THE CHASE ACFT CONTACTED TRACON AS -2 AND LANDED SEPARATELY AHEAD OF THE LEAD ACFT. AT THE DEBRIEF; THE PROFILE AND RECOVERY WERE DISCUSSED AND THE CHASE PLT WAS INFORMED OF HIS ERRORS. CORRECTIVE ACTIONS: 1) REVISE CHKLISTS TO REFLECT SPECIFIC CHASE ACFT TO REDUCE TIME TO DETERMINE CORRECTIVE ACTION INFLT. 2) MORE FORMATION AND EMER TRAINING FOR THE CHASE PLT. 3) IMPROVE COMPANY REQUIREMENTS. SUPPLEMENTAL INFO FROM ACN 748482: TO HELP AVOID THESE SORTS OF DISTRS; THE L39 OPERATORS WILL HOLD PERIODIC REVIEWS AND TRAINING SESSIONS AS A GROUP FOR LESSONS LEARNED AND TO COMMUNICATE UNIQUE CHARACTERISTICS OF THE COMPANY L39 ACFT. I AM PERSONALLY GOING TO CREATE AN ACFT SPECIFIC (WITH DIFFERENCES) CHKLIST THAT IS CORRELATED TO ANNUNCIATOR LIGHTS FOR BETTER EASE OF USE IN THE EVENT OF AN AIRBORNE EMER. WE WILL ALSO INCLUDE A COPY OF THE L39 AFM IN THE TELEMETRY ROOM DURING FLT TEST CHASE SORTIES AS AN ADDITIONAL SUPPORT MEANS IN THE EVENT OF L39 EMER RESOLUTION.