In 1975 we watched as the crew of a DC-3, belonging to a gov't agency, walked up to the AC got in, fired it up and taxied out. As it taxied away we noticed the gear pins and locks were still in.
A very quick sprint to the FSS who called them and told them the control locks were still on, they were on the button, running up the engines by this time.
There was a long pause whereupon they announced that their runups now were complete and they were returning to the ramp.
They came back to the ramp, shut down, went into the terminal, had a coffee, then announced to one and all that they were now ready to depart.
Back to the AC they sauntered, took off all the control locks very carefully, fired up and departed.
They operated into the airfield in question many times - never saw them fire up, taxi to the runway. do a runup then return to the terminal before or after that day.
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