INSTRUCTOR WITH STUDENT ENCOUNTERS CEILINGS LOWER THAN BROADCAST ON ATIS. FILES IFR.

Narrative

FIRST MISTAKE -- NOT TAKING IMMEDIATE ACTION TO AVOID THE MLG TFC PATTERN WHEN I REALIZED THAT THE CEILING WAS NOT 1200 FT; AS STATED ON THE CURRENT ATIS INFO. I WAS ON MY FIRST DUAL AS A CFI WITH MY FIRST REAL STUDENT. WHEN ATIS CALLED CEILINGS AT 1200 FT; I FIGURED WE COULD FLY THE PATTERN AT 700 FT ONCE OR TWICE FOR TOUCH AND GOES BEFORE A FINAL FULL STOP LNDG. THAT WAS MY SECOND MISTAKE. I SHOULD HAVE PLANNED TO GET ON THE GND AS SOON AS POSSIBLE; NOT PLAN FOR TOUGH AND GOES. CONDITIONS WERE WORSE THAN I ESTIMATED. CEILINGS WERE BTWN 400-500 FT IN MOST OF THE PATTERN FOR 27R/L. I REQUESTED A FREQ CHANGE; AND CALLED PATRICK (AFB) APCH FOR A LCL IFR INTO MLB. I HAD ALL REQUIRED EQUIP ON BOARD FOR IFR FLT; ONLY I DID NOT CHK THE VOR FOR THE 30 DAY REQUIREMENT. THE FLT ENDED WITHOUT INCIDENT; OR EVEN THE SLIGHTEST GLITCH; MY STUDENT HAD NEVER EXPERIENCED ACTUAL INST CONDITIONS BEFORE EITHER; SHE HANDLED THE ACFT WELL. I WOULD NOT BE CONCERNED ABOUT HER SAFETY; NOW; SHOULD SHE ACCIDENTALLY ENTER THOSE CONDITIONS AGAIN. IN THE FUTURE I WILL RESPOND MORE QUICKLY TO DETERIORATING CONDITIONS. I ORIGINALLY CANCELLED THE FLT; BUT LATER CHANGED MY DECISION BECAUSE OTHER TRAINING FLTS WERE LEAVING. NEXT TIME I SHOULD FOLLOW IN INSTINCTS. I ALSO NEED TO BE SURE MY ACFT IS SAFE FOR IFR WHEN I DECIDE TO TKOF INTO MARGINAL CONDITIONS. AND FINALLY; I NEED TO BE MORE AWARE OF MY INST CURRENCY. IN THE LAST 6 MONTHS; I'VE LOGGED 5.2 HRS INST; AND 5 APCHS; OBVIOUSLY A LITTLE SHORT OF WHAT I NEED FOR EITHER CURRENCY OR PROFICIENCY.