Hello everyone,
I am kind of a puzzled by this. Was at Changi Airport yesterday night. SQ36 (B777-212ER) was operating a flight from SIN-AMS. In its ATC clearance, controllers
assigned SQ 36 to cruise at FL280 M.84 on the speed, but however, the pilot said that he could only go at Mach.80. Why can't he go at Mach.84 while 15 minutes ago an Air France B777 can accept Mach.84 at FL280 as assigned. The reason controllers try to assign the higest speed possible because of the huge amount of flights departing around the same hour mainly using the same route to Europe. In the end, the ATC controller had to delay all of the rests of the European B744 flights because their minimum cruising speed was at .84 or higer. All the European flights behind SQ 36 went to company frequency to request a change of flight plan to lessen the delays but was denied because they don't want any planes to fly over the Iranian and Afghanistan airspace. SQ 26 was the worst affected, departed Singapore 2 hrs 15mins late. Things can be as bad that the pilots chose to disembark passengers for the 1+ hour wait.
Normally, these European flights uses the same airway, so they got to go in the sequence with 10 minutes to seperate each departure in ATC clearance. If you have to depart 10 minutes behind a flight which has gate real far from the runway, you can only start you push back once that flight has reached the holding point, which is obviously more than 10 minutes of wait. Other European flights, even got the clearance at the same time as the others, but time adds up ( 10 mins behind... which is in return 10 mins behind.... which is also 10 mins behind...) and to add up the push and start and taxi time of those, you know how bad it is.
For the SQ 36 case, the next flight behind him got to choose to depart 19 mins behind him (differ speeds) or 10 mins behind him but forced to cruise at .82. In this sense, it will add time which means delays to other flights. A flight may be ready for push exactly on time but it is possible he will leave an hour later.
SIA flights to Europe are normally never on time and here's why.
alvin
Any idea why SQ 36 had to go at .80? It has definately delayed every other flights.
Thanks
alvin
