On a couple of recent trips into Middle East (DXB), Asia (SIN, HKG), the US (LAX, DFW) and UK (LHR) I've noticed some differences with the descent profiles used into each airport. Assuming the descent starts from a similar altitude between FL370-FL390 the approaches made into DXB and over the last couple of years into SIN and HKG appear to start considerably further out from the airport with the aircraft stepping down gradually to around 10,000 ft and manoeuvring for quite sometime at below 250kts. Whereas arrivals into LAX, DFW and LHR appear to start the descent phase closer to the airfield using a reasonably constant rate of descent with what appears to be less use of "steps". Assuming this is not simply my imagination a couple of questions for you:
- How often do you use the descent profile provided via the FMC and use VNAV / Managed mode to fly the descent? How often do you need to intervene to refine the descent to fit in with the approach controller? Does this vary dependant on the airport you are making the approach into?
- On a few approaches into LAX and DFW the aircraft appear to flatten their descent as they pass 11,000ft or thereabouts. Is this used to wash off any excess speed to achieve < 250kts below 10,000ft? Can the < 250kts speed restriction below 10,000ft get cancelled if there is no slower preceding traffic?
- Approaches into SIN and HKG appear to use speedbrakes more with the stepped descent. Would this be to increase the rate of descent without increasing airspeed or to simply get below a certain altitude by a given waypoint?
- At busy times arriving into DXB it appears the STAR or other arrival procedure takes the aircraft all on series of alternate NW / SE laps paralleling the 30/12 runway pair and gradually closing on the airfield. The direct track appears to be only a "few miles" while the actual track flown takes a huge amount of time at below 10,000ft with a number of noticeable changes in engine thrust as the aircraft descends in steps at the start of each new NW / SE lap. I would imagine this sort of approach and associated manoeuvring would be caused by the large volume of traffic when at the time the schedule QF1 / QF9 / QF 2 / QF10 flights arrive into DXB but it would add significant cost to the airlines with the increased fuel consumption. Also at the end of 14+hr flight from either MEL or SYD could be quite demanding.
- Are there airports / regions that are more adept than others at smoothly handling arrivals?
Thanks in advance....