I've seen Boeing OPT I-pad and what it can do, but I've never used to operationally. I was the last dinosaur with RTOW tables. I'd looked at what weight we could get off with 29c and then see what ASS Temp was available and note the difference in weights. If the ASS TEMP gave e.g. a 5-6ton decrease then that told me there were plenty of margins and I could choose anywhere between 29c & full reduction. I put my finger in the wind and thought about it. The wind was variable across, perhaps might be a little tail as we reached the hold: it was dampish or worse and there was a lot of rubber - probably- at the other end in the stopping zone; etc. etc. A reasoned judgement was made. The tables allowed you to see the rate at which the weight reduced as temp increased. You had a feel for what was going on.
Then came wiz-bang iPads. Punch in the numbers and with no 'feel' out came the most optimum answer and max reduction and so that's what the guys do, now. No feel, no understanding, no decision. It's max reduction or none, nothing in between. Is that correct?
I was sitting on a 3000m runway, with tables, and the F/O asked if I wanted to use reduced. We looked at the numbers and at max ASS Temp we were still not runway limited. So why not. On our return the runway was shorter, same question. We looked at the table and saw that at 29c we were OBS. This continued until about 38c when it changed to RWY limited. He said we could go to 38c. I said that at 29c we had a LONG runway; at 38c we had converted that into a SHORT runway. Was that wise? OK, we had more thrust at ambient temp than actual assumed, but...To show the company we had thought about it we chose 32c, still OBS. I doubt guys think that way with I-pads. I suspect it is max reduction most of the time with no thought.
Last edited by RAT 5; 14th Oct 2017 at 08:06.