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There are several statements about the heights of the reference marks in this logbook entry. It is stated that the profile reference mark for configuration 3 = 1.505 m agl, but also that it is 0.027 m "above top of 1.55m sonic" (boom?), implying a height of 1.55m+0.027m-0.05m 053m = 1.53 52 m agl. Then it says the reference mark for configuration 4 is 0.040 m above the reference mark for configuration 3, which could be 1.65m, 1.55m or 1.57m agl.
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