Pakistan isnt far from Bangladesh. PIA has been flying direct, without refueling both sides of the journey. I m wondering why is that? Is it because PIA flies 777?
Depends on the route and the payload. Also number of fuel tanks. You juggle either passenger or fuel (both add up as payload) but to increase range you have to carry more fuel and therefore less passengers (and their luggage).
787 or 777 does not matter, both can make it to Toronto if they carry lesser number of passengers and higher amount of fuel.
787-9 has longer range than any 777 or other 787 models e.g. 787-8 or 787-10. 787's generally use more advanced and more fuel efficient engines than 777's, mainly because 787's are decades newer. The new 777X's just introduced last month at Farnborough will be using even more fuel efficient (and quieter) engines.
1. If you see the range maps I posted for Biman using Dhaka as a hub in post #2,
a. In the first map 787-9 can hardly make Toronto with 334 passengers, but
b. The same 787-9 can make even NYC (or alternatively - LAX) in the second map carrying way less passengers (280). If you carry less passengers, you can carry much more fuel and make it much farther to more distant cities.
2. The reason PIA 777's can make it to Toronto direct is because their 777's are configured to carry less passengers and more fuel, enabling longer range AND also because they use the shorter arctic, polar route, like Biman.
Plus Any point in Pakistan is a thousand miles closer to YYZ (Toronto) compared to Dhaka which also helps.
3. The outbound 1-Hour fueling stop in Istanbul for Biman 787-9 (see image below) makes it a long, 8,816-mile (14,187km) service with a block time of 20.5 hours. It's different inbound. With tailwinds, it operates non-stop, meaning distance reduces to 7,742 miles (12,459km), and block time falls to 16 hours.
4. Biman's offering is the quickest way to reach Toronto. The schedule is as follows, with all times local:
- Dhaka to Toronto: BG305, Wednesdays: 03:30-13:55; Sundays: 03:00-13:25 (both stop in Istanbul for 1h; block time of 20h 25m)
- Toronto to Dhaka: BG306, Wednesdays: 19:30-21:30+1 (non-stop; 16h); Sundays: 21:00-23:00+1 (non-stop; 16h)
There are a couple of technicalities with these long 16~20 hour block time flights. One is you have to have double the crew or at least 1.5 times the crew (three pilots). You also have to have more flight attendants or have some of them rest in provided resting quarters.
Second, you have to have special equipment for heating fuel oil for polar area high altitude operations, so fuel oil does not freeze and cause problems.
I am sure Boeing took care of both rest area and fuel temperature issues.
I remember the first long range 787 Boeing was trialing - made a non-stop proving flight to Dhaka from Seattle with full test-equipment load. It was welcomed to Dhaka with a rousing water cannon salute. It barely waited an hour to refuel before starting back to Seattle.