A C152 INSTRUCTOR AND STUDENT TAKING OFF ON A NIGHT TRAINING FLT AT A CTAF ARPT CAUSED AN NMAC WITH ANOTHER ACFT ON FINAL CAUSING IT TO GAR.

Narrative

ON A NIGHT TRAINING FLT WITH A STUDENT PLT; AT XA20 LCL TIME; WE WERE PRACTICING NIGHT TKOFS; APCHS AND LNDGS. HOLDING SHORT OF THE ACTIVE RWY; AT AN ARPT WHERE THE CTL TWR WAS CLOSED AT THIS TIME OF THE DAY; WE WERE GETTING READY TO DEPART. A PIPER SEMINOLE WAS CIRCLING TO LAND; AND WE HEARD THE PLT RPTING TURNING BASE. THE APCH SPD OF THE PIPER SEMINOLE IS 90 KTS; SO WE JUDGED THAT WE HAD TIME TO TAKE OFF BEFORE THE SEMINOLE WOULD TURN FINAL. WE STATED OUR INTENTIONS TO TAKE OFF ON THE CTAF AND WITHOUT DELAY STARTED TAXIING ONTO THE RWY AREA; LOOKING IF THE SEMINOLE WAS A FACTOR OR NOT; WE DIDN'T SEE IT ON THE FINAL LEG; HENCE NOT A FACTOR. DURING THE TKOF ROLL; THE SEMINOLE STATED ON THE CTAF: 'ACFT TAKING OFF; THERE IS A SEMINOLE ON SHORT FINAL.' WE DECIDED TO CONTINUE TAKING OFF SINCE WE WERE ALREADY ROLLING; AND IT WAS THE ONLY OPTION LEFT IN MY OPINION. THE PIPER SEMINOLE DID A GAR; REJOINED THE TFC PATTERN; AND WE BOTH LANDED SAFELY ON THE RWY WITHOUT INCIDENT. CONTRIBUTING FACTORS WERE THE LACK OF VISUAL CONTACT WITH THE PIPER SEMINOLE BECAUSE OF THE HIGH WINGS OF THE C152; AND THE FACT THAT WE BOTH TALKED AT THE SAME TIME ON THE CTAF; MY STUDENT STATING OUR INTENTIONS TO TAKE OFF; AND THE SEMINOLE ANNOUNCING HIS TURN TO THE FINAL LEG; NONE OF US HEARD EACH OTHER.