Some background infos:

"Little by little you fly to the mission spot"
that could mean
"During your approach to the target location be very attentive (an unknown flight-route at night-time, with low terrain-flying and behind enemy-lines demands your fully concentration).


"Little by little, little by little you get higher until you see the airfield."
that could mean
"Carefully Bop-Up behind the terrain/hill to get a clear view on the target".


"You won’t even miss the New Year holiday."
=
The pilot get this instruction at 22:00 31.12.20.. local time.
"(If everything runs as planned) you won't even miss the New Year's Eve (here)".
Prerequisites are that the whole operation with outward-flight, the mission-operation itsself and the return-flight will not take longer than 2 hours, which is unusual.

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