Hi pilots, what do you do if a track is cut short on an arrival and it’s not planned or expected and you have too much energy?
Good, you’re using the correct word. Energy. You can be too high, or too fast, but in both cases you have too much energy.
Airlines normally have a fixed point (call it 1,000’) at which you need to be in the normal ‘slot’. On the correct glidepath, correctly configured, and with normal power and speed. As that corresponds to 3 miles to run, it means that the effect of any track shortening has to be fixed in the distance left to run to that point.
In places where this sort of late shortening happens a lot, or where there tends to be an indeterminate base turn point (LAX 24R), you can prepare for it by being a bit slower than the normal profile (if ATC will allow it, which normally they don’t), by being as low as you can get away with, or by configuring earlier than usual and then using more power in the subsequent higher drag configuration.
You do learn to say no as well, I’ve knocked back track shortening many times. My advice to FOs was that if it crosses your mind that you need more drag (be it flap, speedbrake, or the gear), then you actually needed it 30 seconds ago. Also, don’t finesse things, i.e. don’t take partial speed brake because it’s nicer in the cabin. Take the lot, you can always put it back down again. Be prepared to take things out of the normal sequence. In the A380, the configuration sequence was flap 1, 2, landing gear, flap 3, and the flap full. As long as you’re below the speed limit, you can take the gear first, second, or third. Gear and speed brake work better at higher speeds, not lower. Flap is relatively ineffective as a drag source.
There are always two theories for anything. As a general rule, you should always kill the kinetic energy first. Diving height off, at relatively high speed, and then fixing the speed down low, is more likely to result in a go around, than levelling off, killing the excess speed, and then diving off the altitude in very dirty, but slow configuration.