Replies

Right. But you aint having contrail at FL350; the contrail is forced down at a rate of 1000' / minute for approx 10 minutes (or more). So that contrail could be as low as FL200. I'd have to have a forecaster advise me based on atmospheric sounding how low that could be.

According to reporting requirements layers in excess of FL100 are reported to the nearest 1k' (not +/- 5k). Based on the above, I'd still call the layer broken at estimated FL250 (unless I had a PIREP). Then I'd call broken layer CS estemated at whatever is reported in PIREP (can't rely on PRIREP for measured value). I'd bet real money any PIREP for PHO bound flight on 9 Nov at 0000 UTC (or two to three hours earlier) aint reporting a layer higher than FL250; that's because the contrail and the CS layer are merged.

In the middle etage you have to call w/in 500', and below 5000 you have to call to nearest 100'. The pilots begin to get upset when your layer and ceiling heights are significantly in error so as to affect operations. What perecentage of error is 1000' out of 30000'? You get pretty good at calling it (even if its an estimate). When I was in the field I prided myself on calling <5000 layers w/in 50' (that's pretty much spot on).