Singapore to New York: How pilots fly this epic 18-hour journey
Last week saw Singapore Airlines resume its record-breaking flight between Singapore and New York. The 9,530-mile journey takes just over 18 hours on an A350-900, flying a route that can take it close to the North Pole.
With such a long flight comes a number of challenges for the crew of four pilots. A heavyweight takeoff, some serious mountainous terrain, the remoteness of the Arctic and northern Canada and a 20-hour shift all need careful thought and execution.
For the nonstop flight to New York, the A350-900 will require around 100 tons of fuel. With a good payload of passengers and cargo on board, this means that the aircraft will be very close to its maximum takeoff weight of 268 tons.
Manufacturers design the aircraft and engines to be able to get airborne using as little engine power as possible. This is known as a de-rated takeoff. Not only does save on engine wear, but it also reduces the noise experienced by those who live and work near the airport.
However, this creates a trade-off. Take off too far down the runway and you run the risk of going off the end should something unexpected happen. Take off too soon and you’re using more engine power than you need to, increasing engine wear and fuel burn.
Read more: Why pilots don’t have to wear masks when flying
On a twin-engine aircraft such as the A350, the loss of power from one engine during the takeoff run is one of the more serious events that could happen. Although this is highly unlikely, pilots always plan for the worst possible scenario.
Even though an aircraft can safely climb away from the runway on just one engine, should the failure happen whilst still on the ground, it would be preferable for the pilots to reject the takeoff and stop on the runway. However, there comes a point where there will not be enough runway remaining in which to stop safely. So how do we know where this point is?
Before every takeoff, the pilots must calculate the speeds, flap setting and engine power required to take off safely. This includes the engine failure scenario.
If an event occurs before the aircraft reaches V1 (the takeoff decision speed), the pilots know that they are able to stop safely. Any events occurring after V1, the pilots must continue to get airborne. The decision to stop or go isn’t made in the heat of the moment -- it’s a binary decision calculated at a time of low workload.
Normally, at least three pilots will be on the flight deck for the departure and once safely into the climb the two relief pilots will go on their rest. Planning to return from the final rest period around an hour before landing, the remaining flight time is divided in two. So, for a 17-hour, 30-minute flight time, the rest periods would be around eight hours each.
The ultimate aim is to ensure that the crew who are flying the approach and landing are as fresh as they can possibly be. To achieve this, there are a couple of options.
The easiest option is to do a straight 8/8 schedule where, in this example, each crew gets a solid eight hours rest, with the operating crew both returning to the flight deck an hour before landing.
The downside to this is that if the weather conditions have changed at the destination during the time the operating crew were on their break, there could be a lot of work to do with very little time remaining.
Read more: A balanced approach: How weight and loading are critical for takeoff
Another option is a 6/8/2 schedule. In effect, the sleep quality of the relief crew is sacrificed to ensure that the operating crew get a solid rest in the middle of the flight. They then return to the flight deck for the final three hours before landing.
This affords them enough time to wake up properly and then adapt to any changes that may have occurred during their rest period.
On the A350, the rest area for the pilots is hidden away above first class, accessed by a hidden door. Once upstairs, there is a seat for watching the in-flight entertainment and two beds. To ensure a good sleep, these are normally finished with the same bedding as used in first class.
There is a control panel to control the temperature of the rest area and a curtain to close off the foot end of each bed. The major benefit of the rest area is that once the lights are off, it really is quite dark and surprisingly quiet.
That said, there is no bed like your own, and there are very few beds that will throw you around because of turbulence as you try to sleep. If the pilots have managed their sleep well before the flight, they'll hopefully drop off to sleep pretty quickly. If they weren’t able to manage their sleep, it’s going to be a long flight.
Once level in the cruise, the pilots can start to divert their attention onto other tasks. The first is to make a fuel check.
As part of the pre-flight procedure, the pilots will check the flight plan issued to them by the company’s operations department. Not only does this gives them information as to how much fuel they will need for the entire flight but it also breaks it down into how much fuel they require at any given stage of the flight.
Passing the first waypoint after the top of the climb, it is the pilot monitoring’s (PM) job to make a fuel check. They will look at the fuel system display and write down on the flight plan what the actual fuel on board is. They will also write down the time.
Read more: What happens when pilots have to fly without an autopilot?
By comparing the amount of fuel actually in the tanks against what they need to reach their destination as per the flight plan, they can calculate how much fuel they expect to land with. The time check also enables them to see whether or not the flight is progressing as expected. Losing time may indicate that the tailwinds are not as strong as expected.
Fuel and time checks are then completed every 30 minutes for the rest of the flight. By keeping a vigilant eye on the fuel they can determine if they are using fuel faster than expected. If so, they need to work out why. Quite often, it’s because of stronger headwinds or because ATC is keeping them at an altitude lower than their optimum. For these fairly regular cases, they always carry a certain amount of contingency fuel.
As the aircraft crosses over into Alaska, it will cross the Alaska Range with mountains peaks over 20,000 feet. On a moonlight night, these will be quite a spectacular sight. However, no matter the weather conditions, they must always be aware of the height of the terrain around them.
At all times during the flight, even though the pilots may appear relaxed, they are always thinking “What if?” One of the biggest what-ifs is what would they do if they had a sudden loss of cabin pressurization?
Part of the procedure in this event is to “descend to 10,000 feet or the MSA (minimum safe altitude), whichever is highest.” As a result, they need to constantly be aware of what that MSA is.
As part of the printed paperwork, pilots always have a paper copy of the flight plan. Not only does this detail the route, but it also gives them the minimum safe altitude for that particular section of the route.
However, with MSAs in this area of over 22,000 feet, this can cause a problem in not only the loss of pressurization case but also in the case of an engine failure.
Most aircraft have enough oxygen to supply the masks in the cabin for 15 to 20 minutes. This is more than enough time in the case of rapid descent. However, the planned route may not enable them to descend quickly enough to an altitude where the mask is not required.
In the engine failure scenario, as much as an aircraft like the A350 can fly safely on a single-engine, it is often too heavy to maintain the cruising altitude. As a result, they must descend to a lower level. The heavier the aircraft is, the lower that lower level must be.
It gets to a point where this lower altitude, know as the drift down altitude, may be lower than the MSA, which gives them a problem.
In both cases, to enable them to rapidly descend down to the required lower altitude, the airlines’ operations department calculates escape routes that they use to get away from the worst of the terrain as quickly as possible.
Once clear of the terrain, they can then descend down to the lower altitude as required for the rapid descent or drift down.
North Atlantic Tracks
One of the most fascinating points of this flight is the routing. If you take a globe and a piece of string, the shortest route between Singapore and New York is over the top via the North Pole. However, the most direct route isn't always the quickest.
The flight on the way back, between New York and Singapore, actually took a route which will look very familiar to regular Atlantic flyers.
For aircraft to be able to take advantage of routes across the North Atlantic, the North Atlantic Track structure has been created. Before reaching the start of the track, pilots must receive an ATC clearance. This includes the flight level, speed and track to which the crew must adhere to.
At all times of a flight, a good crew will always be thinking, “What if?” What if an engine was to fail right now? What if we develop a fuel leak? What if a passenger gets ill? They will always have a plan of action up their sleeve.
As the aircraft heads into the remoteness of Khazakstan and Uzbekistan, part of this plan of action is always knowing where the most suitable diversion airport is. I use the phrase most suitable, as the closest airport may not necessarily be the best option.
When selecting a diversion airfield, not just any airport will do. The pilots must ensure that the runway is long enough for them to be able to stop the aircraft safely, given the surface conditions. It will take a longer distance to top on an icy runway in Khazakstan than it will on a dry runway in Germany.
In addition, they must also consider what will happen when on the ground. A small airport in Uzbekistan may not have steps high enough to reach the door of an A350 or there may not be any hotels in which to accommodate scores of passengers.
As a result, the nearest suitable airport may be several hours flying time away.
Like radar, the range of normal voice communications is limited to a few hundred miles. As the very high frequency (VHF) radio waves travel in a straight line, the curve of the earth becomes an impediment. The earth literally gets in the way of transmissions being sent from aircraft.
Traditionally, oceanic communications relied on high frequency (HF) radio communications. These don’t require line of sight for a connection as they use the earth’s upper atmosphere to bounce back down. However, these are notoriously unreliable as they are affected by the earth’s magnetic field and can quite often be unusable. As a result, HF comms are mostly used as a backup.
The advent of satellites in orbit above the earth solved this problem. By using satellite communications, the CPDLC system can keep the pilots in contact with the controllers on the ground.
Each time the aircraft crosses a waypoint on the track, the communications system automatically sends a position report to the controllers on the ground. This enables them to know what time the aircraft passed that point and at what altitude. It also tells them at what time they estimate the next waypoint. In the absence of radar, these position reports enable controllers to keep tabs on aircraft and ensure they remain safely separated.
As the flight approaches its oceanic exit point, it is transferred to controllers in Europe. Here, back under radar and VHF radio range, the aircraft has to be integrated into the domestic traffic flow. Once off the track, pilots are then able to return to their preferred speed, if different to the oceanic clearance.
The flight between Singapore to New York is a monster. As a result, some serious thought goes into all elements of the flight.
It's imperative that the crew are well-rested, ensuring that they are in peak condition when it comes to landing the aircraft some 18 hours after they took off. The route itself provides some challenges, from the high mountains of the Himalayas to the remoteness of northern Canada.
However, like any other flight, it all comes down to the three basic fundamentals of flying an airliner. Aviate, Navigate, Communicate.