MovieChat Forums > Amelia (2009) Discussion > Direction Finder?

Direction Finder?

posted 14 years ago by nick suess
2 replies | jump to latest

Much was made about the "direction finder" having a flat battery due to being left on all night.
Firstly, what is this "direction finder"? I am a pilot, and (pre-GPS) used to make lots of use of a "direction finder" in the aeroplane which provides the relative bearing of a land-based radio signal. Did they have something which did the reverese? Gave the bearing of the signal from an aeroplane? Maybe, but then they talked about trying to get a bearing on her transmissions, but couldn't because they were too brief, not because the battery was flat. So was this all gobbledegook? Is there any eveidence whatever that some junior rating left this supposedly vital item of equipment on all night and that a flat battery contributed in any way whatever to the loss of the flight?
Secondly, a flat battery? They are on a ship with masses of electrical power available. Knowing that lives depended on this, surely they'd have hooked it up to some other supply, perhaps just put the battery on charge???
DUH, it annoyed me!!

[–] 14 years ago

[deleted]

[–] moleski-2 14 years ago

Firstly, what is this "direction finder"? I am a pilot, and (pre-GPS) used to make lots of use of a "direction finder" in the aeroplane which provides the relative bearing of a land-based radio signal. Did they have something which did the reverese? Gave the bearing of the signal from an aeroplane?

Yes, exactly. Here is a discussion of DF with respect to Earhart's disappearance: http://tighar.org/wiki/Direction_finding.

Maybe, but then they talked about trying to get a bearing on her transmissions, but couldn't because they were too brief ...

It's more complicated than that.

- AE specified the wrong frequencies for HER DF equipment (7500 kHz was way beyond her equipment's capacity).

- AE transmitted on a frequency that the ship could not DF on (she was on 3105 kHz; the ship could not DF above 1400 kHz, I believe).

- she did not give a long enough signal

- the HFDF equipment borrowed from the Navy was turned on too early, was not well designed, and did run out of battery power before the fact that this was an emergency was realized.

Even if AE had given a signal that was long enough for DF and that was in the right frequency range for the equipment on Howland Island (Navy, HF, dead batteries) or for the equipment on the Itasca (Coast Guard, low frequency, shipboard power), AE's radio was not receiving voice transmissions from the Itasca. Even if they had a bearing on her, they could not have communicated it to her. But it would have helped immensely in defining the right area to search.

Marty
TIGHAR #2359