[ARC5] LF in a B-17?

[David Stinson]

I've found documentation concerning this thread
about why B-17s and other heavy WWII aircraft
carried LF capability.

While providing DF signals is a documented use,
at least for Navy aircraft,
there is another use that included Army Air Force units.
A clue can be found in the flying terminology
of the 1930s and 1940s, when an aircraft
was referred to as a "ship."

During flights over open ocean,
such as ferrying flights or even short hops
between the eastern U.S. and the Canadian coast,
radio operators were required to
keep MF distress watch on 500 KC at 15 and 45 minutes
after the hour, just like other "ships"
sailing on the waters below,
and to be able to answer distress calls.

I submit an excerpt from a radio log sheet
from a AAF aircraft, CW callsign "GNJY,"
phone callsign "Beggar Able,"
which ferried from Dow Field in Bangor, Maine
to Gander Field, New Foundland on August 25th, 1944,
sixty years ago tomorrow:

----------
1515 Take off.
1521 Requested radio check from Bangor Flight Control on 4220 KC HF.
      They replied on 375 KC LF "read you R5 S5
      and on frequency."
1545 Tuned to 500 KC and monitored.  No signal heard.
1600 Received a CW message from WYXN on 7445 KC.
1615 "Guarding Inter. Distress Freq. 500 K.C."
1618 Monitoring 4220 K.C.
----------

I also submit an excerpt from a training document issued
19 June 1944 at Mitchell Field, N.Y., 110th AAF Base Unit,
office of the Communications Officer, Restricted and
entitled "The Most Important Member,"  presenting a number
of points about the responsibilities
of the aircraft radio operator.

------------
8.  DO YOU KNOW DISTRESS PROCEDURES?
This is a MUST, for the crew will be counting on you
to obtain aid when everything else fails....
Do you know of the guard on 500 K.C., especially
during the three-minute international Silent Periods
starting at 15 minutes and 45 minutes after each hour?...

9. HAVE YOU TUNED YOUR LIAISON TRANSMITTER
    BETWEEN 200-600 K.C. WHILE IN FLIGHT?
This is a required procedure on many flights overseas...
-----------

Given the monitoring times of 1545 and 1615,
plus the use of the term "guarding" in the aircraft
radio log, plus the excerpt from the training document,
we can confidently conclude that, among other duties,
the LF capabilities of  WWII AAF heavy aircraft
were there to comply with the Distress requirements
of "ships" capable of transiting the open ocean.

73 DE Dave Stinson AB5S