Story 11 - Loss of Flash Message
Helicopters not arriving for a Mission
By Peter “PJ” Brown, 110 Sig Sqn, South
Vietnam
(18 Dec 1967 – 19 Dec 1968)
Photo: Australian Troops
waiting for helicopters in 1968. AWM
ERR_68_0631_VN
Situation
Still dark, the sky is starting to
lighten, high in the eastern sky. The assault force is probably
resting on packs, fully psyched and gunned up. The assault force
has been quickly assembled on Kangaroo Pad at the 1st
Australian Task Force, Nui Dat because an opportunity has been
detected, a response formulated. The assault force is waiting,
listening for the sound of the Helicopters coming to lift the team
into battle.
Stop Listening:
Why:
Message Handling
Handling formal messages by the Royal
Australian Corps of Signals in the Vietnam War was a detailed
process to ensure precedence, traceability, distribution, security
and timely delivery.
Precedence is a designation assigned to
a message by the originator to indicate to communication personnel
the relative order of handling and to the addressee the order in
which the message is to be noted. The common designations used
in the Vietnam War in descending order of precedence were: Flash,
Immediate, Priority and Routine.
For example: Flash messages are
reserved for initial enemy contact or operational messages of
extreme urgency. Brevity is mandatory. Flash messages
are to be handled as fast as humanly possible, ahead of all other
messages, with in station time not to exceed 5 minutes.
Messages of lower precedence are interrupted on all circuits
involved until the handling of the Flash message(s) is completed.
Losing a Flash Message
It’s not good to lose a message. We
almost never did. As messages go, if we were going to lose one, a
routine message, like the one ordering a pallet load of boots to be
delivered next month would be the way to go but not forgiven.
Processes were in place, the error would have been detected, at
shift change and the situation corrected.
However we lost a flash message in the
Vung Tau COMCEN, that was to task helicopters for the urgent mission
in 1968.
Two things went astray, well actually
three if you count the message. The following was discovered by the
investigators.
1.
The message was received in the COMCEN
typed and transmitted but the receipt to the next station was not
checked! What should have happened, and did not, was that a phone
call should have been made to the next station (Nui Dat) stating
that “a flash message (insert number and date time group) has been
sent, acknowledge receipt that confirmed onward transmission”. So,
the message was sent but the safety trigger, the phone call was not
made to the Nui Dat COMCEN.
2.
The message got lost or as we signallers
say went into the ‘ether’ and did not come out.
What Happened to the Flash Message?
The explanation is bound up in the type
of telegraph cipher machines we were using in South Vietnam. It was
the KW-7 (Orestes).
Photo:
KW-7 (Orestes).
Internet Source
This equipment is simplex equipment
meaning, that for a single transmission two machines were used one
to transmit one to receive, in one direction only. They can be wired
up to suit many configurations as the situation demands. All cipher
systems are built to protect messages that are encrypted using it.
They also have to be capable of working in a noisy electronic
environment, or in other words over a radio equipment that is not a
perfectly noise free circuit (if there are any). If for
instance an encoded character is received incorrectly (changed to
another character) then the de-ciphering process has been derailed,
sometimes it is recoverable sometimes it is not. If it is, then
there is what is called an error extension process, a few characters
of the word will be corrupted, but in the context of a message the
word or words are able to be reconstructed by the operator. If not
then the message has to be resent in its entirety. Those basic
requirements are what caused the message to be lost.
Well if you don’t count my involvement!
There was one process that had to be error free or no decoding process would start. The sending operator had to press the send button; the machines had already been set to the code in use. The send button started a pre-amble transmission.
First a slow speed series of marks and
spaces (one’s and zero’s). This alerted the receiving machine to
the fact that a “set up message” was probably following.
Photo: Message tape with
baudot coded message for retransmission. Inserts: Baudot
code details (top)
and mark/space details (bottom). Internet Source
The operator holds down the send button
for as long as he thinks necessary and releases it. Then follows an
authentication process and a message to set the decoding registers
to the same place as the transmitting machine. This has to be error
free.
If that machine to machine message is
not received word perfect. Then the decoding process will not start
and there will not be any indication at the receiving station that
there was one. And nobody is any the wiser. All noise signals are
squelched out to save paper and protect the operator’s sanity. It
gets quite noisy in a teleprinter paper punch environment.
Photo:
Comcen telegraph tape preparation position showing type of telgraph
equipment used (Kieinschmidt). 104 Sig Sqn website
(Photo 91-3)
And so to
my confession, forgive me sir for I have sinned. I caused the
interruption. How do we know well the investigators (previously
mentioned) can track down by our logbook entries.
In South Vietnam, most of our communicating
equipment were based on valves (electron tubes). Electron flow is
controlled in a high voltage environment by a vacuum (tube) heated
to a high temperature by incandescent heating elements.
These failed routinely. If we were to
wait for them to fail then messages would be lost or at least
delayed. To reduce the impact of known failure point’s routine
preventative maintenance is carried out. To this end valves are
monitored, working voltages and currents are are logged onto
recording sheets.
I was carrying out one such activity
when my clipboard bumped into the Transmitter of the Radio Set
AN/TRC-24. This Radio Set was the bearer from HQ 1ALSG (Vung
Tau) to HQ 1 ATF. The transmitter circuit breaker
dropped out. Being in the vicinity I immediately reset it. I was
just in time to see the carrier equipment lights on the multiplexing
equipment’s (F1830 Group of TA-5006/U’s) turn red then green again.
No worries I think, not long enough to warrant a log book entry.
Checked with the keyboard operators, dead quiet not a bit of
punched tape stirring. Checked with the telephone switchboard
operators, all quiet, suggest that they give “Nui Dat” a call
because I lost them for a few seconds. Routine alignment and level
checks were not due for a few hours and it did not seem necessary to
bring them forward.
Photo (Left): Radio Set
AN/TRC-24 as installed in the Comcen, Vung Tau.
Photo (Right): Syscon and equipment in the Comcen, Vung Tau.
Photos from 104 Sig Sqn and Pronto in SVN websites
It has been determined that in this
period the preamble machine message and the following FLASH message
were lost into the ‘ether’.
Summary
Helicopter mission was cancelled
because of the no show of the aircraft and my poor signalman
technician arse was sore for a week!