Originally Posted by
framer
Hi there Nok,
I like your hint, or ‘rule of thumb’, it helps with a broad understanding of the importance of crossing the threshold at a sensible height.
If you’ve calculated your landing distance at 2000m then you are in a pretty fast and heavy aeroplane.
I can see that the aircraft is quite sophisticated as well.
One thing I have noticed over the last few years is that when I’m sitting beside a person with relatively low flight experience, ( say 2000hrs) and we are crossing the threshold of the landing runway, they could do a nice job of the landing, and they could tell me what 3x7 equals, but they couldn’t do both at the same time.
When you are crossing the threshold it isn’t the time to try and determine your deviation from the 50 foot ideal and then make a simple mathematical calculation, and then use the answer to make a decision about whether to continue to land or conduct a missed approach. It’s simply too cumbersome.
But that is no problem because on 99% of landings in a big fast sophisticated aeroplane, you will have markings painted on the runway that give you good information about your runway performance. Most of the time you don’t want to touch down before the 1000 foot markings, you’d be fairly comfortable with touching down at the 1500 foot markings, and you’d be a bit disappointed in yourself if you landed on the 2000’ markings. Beyond the 2000 foot markings we are starting to get into more nuanced decision making conversations that will differ for each weight and each runway.
So although I like your rule of thumb regarding threshold crossing height, I think it best serves pilots as an easy way to articulate the importance of accurately flying the planned approach profile while they are sipping coffee in a classroom, and could be problematic if applied in real time.
I suspect that would end up with briefing a defined go-around point i.e. if we have not touched down by the 2500ft mark, we must go around. That would vary based on weight, aircraft type, runway length etc. Float is less of an issue at Heathrow than Florence. Float is less of an issue on an ATR than a 739.
ROPS/ROWS does this on an on-the-fly basis.