Narrative:

Electrical failure occurred on the way into mlb. No indications on the alternator indicator light or the gauge warned of a problem. The first radio failed, so a second radio was to be used. Before melbourne tower could be reached, the second radio failed. 7500 was mistakenly placed in the transponder instead of 7600. The radios continued to go on and off. We could still hear the tower and other aircraft, but could not transmit. We had traffic for runway 4 in sight, so we decided to approach and land. The emergency checklist was read off for emergency gear extension. While this was occurring, we received an alternating red/green light gun signal, so a go around was initiated. At this time the gear was down, and we proceeded for right traffic runway 4 with a flashing green light. Once the light gun became solid green, the aircraft landed. We taxied with light gun signals back to the ramp. Class D airspace was entered without acknowledgement from the melbourne tower, and 7500 was mistakenly placed in the transponder. There was no way to avoid entering class D airspace with 2-WAY radio communications, but I should have not engrossed myself in the electrical failure and gear problem to the point that I did not notice the incorrect transponder squawk code.

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Original NASA ASRS Text

Title: A LOW-TIME CFI SET THE HIJACK SQUAWK CODE, INSTEAD OF THE RADIOS OUT CODE, WHILE PENETRATING MLB CLASS D AIRSPACE.

Narrative: ELECTRICAL FAILURE OCCURRED ON THE WAY INTO MLB. NO INDICATIONS ON THE ALTERNATOR INDICATOR LIGHT OR THE GAUGE WARNED OF A PROB. THE FIRST RADIO FAILED, SO A SECOND RADIO WAS TO BE USED. BEFORE MELBOURNE TWR COULD BE REACHED, THE SECOND RADIO FAILED. 7500 WAS MISTAKENLY PLACED IN THE XPONDER INSTEAD OF 7600. THE RADIOS CONTINUED TO GO ON AND OFF. WE COULD STILL HEAR THE TWR AND OTHER ACFT, BUT COULD NOT XMIT. WE HAD TFC FOR RWY 4 IN SIGHT, SO WE DECIDED TO APCH AND LAND. THE EMER CHKLIST WAS READ OFF FOR EMER GEAR EXTENSION. WHILE THIS WAS OCCURRING, WE RECEIVED AN ALTERNATING RED/GREEN LIGHT GUN SIGNAL, SO A GAR WAS INITIATED. AT THIS TIME THE GEAR WAS DOWN, AND WE PROCEEDED FOR R TFC RWY 4 WITH A FLASHING GREEN LIGHT. ONCE THE LIGHT GUN BECAME SOLID GREEN, THE ACFT LANDED. WE TAXIED WITH LIGHT GUN SIGNALS BACK TO THE RAMP. CLASS D AIRSPACE WAS ENTERED WITHOUT ACKNOWLEDGEMENT FROM THE MELBOURNE TWR, AND 7500 WAS MISTAKENLY PLACED IN THE XPONDER. THERE WAS NO WAY TO AVOID ENTERING CLASS D AIRSPACE WITH 2-WAY RADIO COMS, BUT I SHOULD HAVE NOT ENGROSSED MYSELF IN THE ELECTRICAL FAILURE AND GEAR PROB TO THE POINT THAT I DID NOT NOTICE THE INCORRECT XPONDER SQUAWK CODE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.