Before Amelia Earhart disappeared on her last flight she let it be known to all concerned that she would be transmitting at a quarter past the hour. She also said she would listen on the hour and half hour. In 1937 aircraft radios were quite different than they are today. Amelia had a radio that received and another radio that transmitted.

On her first around the world attempt between Oakland and Honolulu the generator went out several hours before she reached her destination. It was determined upon landing that the current limiter fuse had blown because the amperage being used on board the Electra was too high. The current limiter fuse is in the engine compartment so it is impossible to repair in-flight. The remedy was for her not to run the receiver radio when she was transmitting.

Today when we turn on a radio it comes on almost instantly, which wasn’t the case in 1937. The radios were all the old tube type and required several minutes to warm up before they could receive or transmit. That is the reason she set times to transmit and receive so the radios would be operational when they were needed.

Amelia transmitted at a quarter past the hour (between 12 and 18 minutes past) at all but 3 times during the course of her final flight. We can account for 14 transmissions. Of the three calls she transmitted (other than at her assigned times) 2 were under emergency conditions and one was a position report with a request for the U.S. Coast Guard Cutter Itasca to take a bearing on her voice.

Her six radio transmissions during the first half of her final flight were very short.  It has been theorized that it was because she didn’t want to take a chance on the Japanese tracking her. A very believable reason since no other theory makes much sense. At 10 and half hours into the flight she still could have turned back to Lae if she had blown the fuse.

On the last part of her trip she was in a quandary. On her first attempt she had held the transmit key down for long periods so Pan American stations could get a “fix” on her and, as a result, had blown the current limiter. She had to wait until she was very close to Howland Island to transmit for long periods because if she blew the current limiter fuse again, she would have nothing but battery power to run on. That meant she would lose any chance of direction finder assistance when she got close to Howland. Also, she couldn’t lower the landing gear if the battery went dead and the generator wasn’t charging. If she had located Howland Island without electrical power she would have been forced to land with the gear up.

IF YOU KNEW THAT USING THE TRANSMITTER TOO LONG COULD RESULT IN LOSING THE ABILITY TO LOWER YOUR LANDING GEAR, WHAT WOULD YOU DO?