How Flying Works
How Flight Routes Are Planned — and Why Crews Change Mid-Flight
Singapore Airlines’ nonstop flight from Singapore to New York, SQ23/SQ24, is the longest scheduled commercial route in the world — roughly 9,500 miles, 18 to 19 hours in the air, flown on a specially modified Airbus A350-900ULR. No two pilots fly that entire duration. Four do: two captains and two first officers, taking turns at the controls while the off-duty pair sleeps in a dedicated two-bed rest compartment. It’s the clearest possible illustration of two things most passengers never think about together — how a route actually gets built before a flight ever departs, and why the people flying it aren’t necessarily the same two people the whole way.
The route is built by a dispatcher, not the pilot
Before any flight departs, an airline dispatcher, working from the airline’s operations center and typically responsible for roughly 20 flights at a time, builds the proposed route using flight-planning software that generates multiple candidate paths and calculates total fuel burn for each. The dispatcher weighs forecast winds, airspace restrictions, aircraft performance limits, and alternate airports before selecting and refining the best option — then, in US operations specifically, both the dispatcher and the captain personally review and sign the dispatch release before the flight is legally permitted to depart. That's genuine shared legal responsibility for the route and the flight's safety, split between two people who never fly the aircraft together, one in an office on the ground and one in the cockpit.
The real numbers
SQ23/24 — Singapore to New York, by the numbers
18-19 hrs
Flight duration
The world's longest scheduled commercial route
4 pilots
Cockpit crew carried
2 captains, 2 first officers, taking turns at the controls
13
Cabin crew, including purser
With a separate 6-bunk dedicated rest area
2 beds
Pilot rest compartment
A dedicated, separate area from the cabin crew's bunks
Why the crew has to change at all
Flight Time Limitation (FTL) rules exist specifically to prevent fatigue, and they cap how long a pilot can remain actively at the controls without a genuine, defined rest period — not a nap in the jump seat, a real break in a dedicated rest facility. No two-pilot crew is legally permitted to fly an 18-19 hour sector alone under those rules, which is exactly why Singapore Airlines carries two full cockpit crews instead of one. Partway through the flight, the resting pair swaps in: a formal handover briefing covers the current fuel state, weather, and any open items, responsibility formally transfers, and the pair coming off duty goes to rest while the fresh pair takes over — the same shift-change discipline used anywhere duty-time rules matter, just happening 35,000 feet over an ocean instead of on the ground. Cabin crew operate under a related but separately regulated set of rest rules, which is why the aircraft carries 13 flight attendants with their own six-bunk rest area rather than just enough staff to cover the flight if nobody needed a break.
None of this is unique to one airline or one aircraft — it’s the same underlying logic behind every augmented crew on every genuinely long route, just most visible on the single longest one currently flying. The route gets planned on the ground, hours in advance, by people who never board the aircraft; the people who do board it aren’t necessarily the same two who land it — and neither fact is a compromise. Both exist specifically because they make a very long flight measurably safer than the alternative of asking one crew to do the whole thing themselves.
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Sources & Further Reading
Common Questions
Frequently Asked Questions
Does the pilot choose the route?
Not from scratch. A dispatcher, working in the airline's operations center and typically handling around 20 flights at a time, builds the proposed route using optimization software, weather data and airspace restrictions. In US operations, both the dispatcher and the captain have to review and sign off on the plan before departure — real shared legal responsibility, not just a formality.
Why can't the same two pilots just fly an 18-hour flight and rest in turns in their seats?
Because duty-time regulations don't allow it. Flight Time Limitation rules cap how long a pilot can be actively at the controls without a genuine rest period, defined specifically as time away from operating duties — which is exactly why ultra-long-haul flights carry extra pilots and real bunks, not just an understanding that someone can nap in the jump seat.
How does a mid-flight pilot swap actually work?
One qualified pilot pair hands over active control to another qualified pair already on board, following the same handover discipline used for any shift change — briefing the current situation, fuel state, weather and any open items before formally transferring responsibility. The outgoing pair then goes to the dedicated rest compartment for their scheduled break.
Do cabin crew have the same rest requirements as pilots?
A related but separately regulated set of rules, generally requiring at least 10 consecutive hours of rest across a duty period on international operations — which is exactly why Singapore Airlines' 18-19 hour Singapore-New York flight carries 13 flight attendants with their own dedicated six-bunk rest area, not just the four pilots.