If you can make the round trip in less than 24 hours you need one plane. 24-48 needs two planes, which of course ignores maintenance requirements. That said, rotating planes around can be far more efficient. For instance, you wouldn't have a plane returning from a 30 hour round trip sit around for 18 hours until it leaves again, you'll send it somewhere else. (Not that some planes don't sit for long periods of time, but they are usually undertaking some maintenance during the downtime)
Why do Aerospace Engineering students have to turn things in on time?
VV701 From United Kingdom, joined Aug 2005, 8236 posts, RR: 24
Reply 6, posted (2 years 2 months 2 weeks 5 days 13 hours ago) and read 3906 times:
LHR-BOM is 3,899 nm on the great circle route. BA's 10:55 LHR departure for BOM arrives at 00:35. The return flight departs at 02:35 and arrives back at LHR at 07:30, 3hrs and 25 mins on the clock before its original departure time. So one aircraft could operate this near 4,000 nm flight six days a week (leaving a day for routine maintenance).
PA515 From New Zealand, joined Nov 2007, 1073 posts, RR: 0
Reply 7, posted (2 years 2 months 2 weeks 5 days 13 hours ago) and read 3670 times:
Quoting rutankrd (Reply 5): Over 28 hour (Basically Europe- Antipodes) needs a minimum of 3 frames however in reality you would require a further frame for downtime and again rotating over a shorter intermediate route.
That's how the Air NZ fleet of five 77W's is used:
AKL-LAX-LHR-LAX-AKL (Daily) NZ2/NZ1 (3 aircraft)
AKL-LAX-AKL (ex Tue) NZ6/NZ5 (2 aircraft) -- Tue is a 77E
Aircraft dep AKL in the evening and return in the morning three/two days later. Downtime available is Tue morning to Thu evening. Two aircraft at AKL each morning doing an AKL-BNE-AKL, AKL-MEL-AKL or AKL-NAN-AKL most days before heading back to LAX that night.
Next year the fleet increases to seven 77W's with the 744 replaced AKL-SFO-AKL (Daily or ex Tue) NZ8/NZ7 (2 aircraft).
mandala499 From Indonesia, joined Aug 2001, 7331 posts, RR: 78
Reply 8, posted (2 years 2 months 2 weeks 5 days 13 hours ago) and read 3618 times:
4000NM? I'm assuming that's air distance... in still air it would be Give and take 9H30 to 10hrs... so that's 20hrs return plus 2 hours on each end... so that makes it 1 aircraft...
But when you add maintenance, slots etc, 2 is the minimum, mix it with another shorter route.
7500NM? You'll need 2 minimum, most likely 3... if nonstop. If not, then 3 minimum...
So have all the above, then add timezone differences, airport operating hours, slot availability, etc... and it would screw up the above numbers
When losing situational awareness, pray Cumulus Granitus isn't nearby !
Roseflyer From United States of America, joined Feb 2004, 10414 posts, RR: 52
Reply 9, posted (2 years 2 months 2 weeks 5 days 9 hours ago) and read 3516 times:
Most airlines don't operate their planes on isolated routes. The airplanes usually freely rotate throughout the network. So while if the block time is under 10 hours, it could only require 2 planes, technically it isn't a one for one relationship. Maintenance needs some extended ground time once a week and then more significant maintenance every two or three months.
When an airline adds a route they look at their spare aircraft, downtime and extended ground time to see how to schedule the flight. The more time the plane is in the air, the poorer the reliability. Each airline is different.
If you have never designed an airplane part before, let the real designers do the work!