I'm a newbie (relative). A few of us on here are from the last 15 years or so.

I know what an ALM is but what is an ACM(O) please? In 1964-68 we did have a few trained observers but that was it.

ACM(O) is an Aircrewman Observer. He was the smart person with a map who always knew where he was and often shared that information with the Pilot. This was as opposed to the ACM(G) who was an Aircrewman Gunner. Gunners started (I believe on the Westland Scout), which could be fitted with the SS.11 Anti-Tank missile system. This was a dustbin sized wire-guided missile with the speed of an arthritic miner, but could deliver a reasonable punch. The gunner had to optically track the target (Ferranti AF120 Sight), squeeze the trigger, and then when all the smoke had cleared, try to fly the dustbin full of HE to the same grid square as the target. One hand tracking the target, one hand flying the missile, those Gunners certainly had some awesome hand-eye coordination.

All this changed with the introduction of the 2 pilot system, after someone realized that the entire armed action capability of Army Aviation relied on a small number of well-motivated Junior NCO's in the left seat!

Which then led to the debate - on Lynx - as to which role the Officer should play; should he command and fly the helicopter while the gunner fired the TOW or should he have direct control of the weapons while the corporal flew the helicopter. ISTR that went round the buoy a few times;)

Aircrewman (O)
 

As Ross Mallock had it in the song, "The Right-hand Man in the Left-hand Seat."

Another arthritic miner on it's way to oblivion with the Gunner about to find out if this particular one is a rogue.

Thanks Two's In. Yes remember the SS11, did some trials using 26 flights Alouette 2s in Germany late 1967. Two pilots operating, I, ('gunner'), sat next to the Alouette pilot, (flying), took the target details over the R/T, gave instructions to pilot, used a pair of binoculars with a bloody great gyro attached to stabilize them, called 'fire', recording equipment plus officer in back giving commentary, called 'hit' when time of flight achieved. All done with no missiles at all! Went on for about a week, never did see a report though. Left Army Feb. 1968.