Aviation does not usually require the precision assumed here. The aircraft would have flown fine anywhere between (say) 150k and 300k, so an initial-nav indicat

Aviation does not usually require the precision assumed here. The aircraft would have flown fine anywhere between (say) 150k and 300k, so an initial-nav indication of (say) 250k +/- 20k would tell the crew that things are "close-enough". More useful at the time would be to set a "sensible" power level and maintain approximate altitude ... and looking out the window is usually helpful!