Originally Posted by
haughtney1
Le Pin,
My understanding of Maestro is that it is designed to optimise the landing sequence using the arrivals part of it, and it keeps recalculating etc etc, a bit like my Garmin.
My understanding is that the distance of 200nm from destination is user defined, rather than system specific? I did ask btw about our sequence on taxi in, no preceding arrivals for 6 or 7 minutes, no departures for 4 minutes, so I was and still am bit baffled.
Maestro works by using untouched landing times of all the arrivals - basically the system estimate for the fix plus the time it calculates (to the second I believe) you'll take from the fix to run around the STAR to the threshold. The sequence is simply the order of untouched landing times. This isn't set in concrete until quite late in the piece so you can jump around a bit at times.
It then takes the acceptance rate (time between arrivals), spaces the sequence accordingly and calculates landing times. It then calculates your time for the fix so you land at the required time.
Meaning if you get several aircraft with very similar untouched landing times it's possible to go back (or forward) several spots if estimates change a little. i.e. you can go from 0 delay to 10 minutes just like that. 10 minutes would be unusual but it's entirely possible.
We have plenty of other things to do besides fiddling with Maestro that have higher priority such as separation and coordination. We'll take a look at it from time to time but things can change rapidly and catch us unawares. Changes rely on us noticing them - we don't get an alert to warn us.
As to why the gap, it could have been they managed to shorten up some of the aircraft ahead and compressed the sequence a bit and you were a bit slower than expected. It could have been a space left for a transiting medevac chopper. We don't just leave holes for the fun of it.