What do pilots do during the cruise?
It's quite often said that the job of a pilot is very much like that of an anesthetist. It's pretty busy at the start and end of the operation, but in the middle it's a bit more relaxed. With the intensity of the departure complete, the atmosphere in the flight deck relaxes.
The pilots instruct the Autopilot to do the dogs work of keeping the wings level and flying the route entered into the Flight Management Computer (FMC) on the ground. Whilst one pilot is always responsible for ensuring the Autopilot is doing exactly what they expect it to do, it creates spare capacity for the crew to attend to other matters.
On a typical 10-hour flight from Los Angles to London, there's plenty to be done whilst up at 37,000 feet. It may seem like the pilots are just there for the ride, but that couldn't be further from the truth. Here's what is going on in the pointy end whilst you're trying to get some sleep.
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Fuel and Time Checks
It will normally take around 30 minutes for a heavy 787 Dreamliner to climb from the runway to its initial cruising altitude. During this time, we normally do very little except concentrate on flying the aircraft and talking to ATC. Once level in the cruise, we can start to divert our attention onto other tasks. The first is to make a fuel check.
As part of our preflight procedure, we check the flight plan issued to us by the company's operations department. Not only does this gives us information as to how much fuel we will need for the entire flight, it also breaks it down into how much fuel we require at any given stage of the flight.
Passing the first waypoint after the top of 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.
By comparing the amount of fuel actually in the tanks against what we need to reach our destination as per the flight plan, we can calculate how much fuel we expect to land with. The time check also enables us to see whether or not the flight is progressing as expected. Losing time may indicate that the tail winds 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 we can determine if we are using fuel faster than expected. If so, we need to work out why. Quite often, it's because of stronger head winds or because ATC are keeping us at an altitude lower than our optimum. For these fairly regular cases, we always carry a certain amount of contingency fuel.
Rarely — and I mean very rarely — a discrepancy in the fuel checks may be a result of a fuel leak. In this situation, there is a regimented checklist that we must follow to ascertain if there is indeed a fuel leak. Depending on where the leak is coming from, we may have to shut an engine down. If the leak cannot be controlled, an immediate diversion is made before the situation gets any worse.
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.
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. You'll see why shortly.
Two hours into the flight from Los Angeles to London, the aircraft is approaching Aberdeen, South Dakota.
Whilst Aberdeen does have an airport, we need to be sure it’s somewhere that we can not only land the aircraft, but also get airborne again. The first thing we will check is the runway length. At just 2,100 meters, landing a heavy 787 would be tight. There may also issues with parking and having steps big enough to reach the door. All in all, not a great option.
Off to the left is Bismarck, North Dakota. With a 2,700-metre runway, it’s a viable option, but on checking the weather, heavy snow is reported. Maybe not the best place to divert to.
A little further along the route is Minneapolis, Minnesota. It has a couple of runways over 3,000 meters long, the weather is great and the ground facilities cater for large jets like the 787. A suitable diversion airport. To aid our situational awareness, we’ll put a ring around the airport on our map display.
The airspace over the North Atlantic is some of the busiest in the world. However, as there is no radar coverage, there is a system in place to ensure that all aircraft remain safely separated for the duration of their crossing.
To aid this flow, a number of tracks are created by ATC each day. These enable pilots to take advantage of the most favorable winds going eastbound and avoid the strong headwinds going westbound. As there are hundreds of aircraft crossing the Atlantic each day, they must not only be separated laterally, but also vertically. Normally in 1,000-foot increments.
As the pilots near the entry point to the oceanic track, they request a clearance from ATC to fly at their chosen altitude and speed. These requests are collated by ATC and a clearance is issued to each flight.
On receipt of the clearance, both pilots must then stringently check that the route, altitude and speed that the aircraft has been programmed to fly matches the clearance. If there are any changes, normally to the altitude or speed, corrections must be made.
On rare occasions there is a bottle neck on one of the tracks, and a re-clearance onto another track may be made. This involves some serious workload to accurately change the route in the Flight Management Computer and, once again, check for any errors.
A major part of long-haul flying is managing tiredness. Some flights can be more than 17 hours long, so ensuring that we perform at our best during the most critical stage of the flight — landing — is of utmost importance.
To help us achieve this, sleep is a major part of the flight. On the longer flights, there will be one and sometimes two extra pilots. This enables us to take it in turns to get some shut eye.
That said, sleeping in the cabin is far from ideal. It’s often noisy with the cabin service, sometimes too hot and normally too bright to get any quality rest. Fortunately, most long-haul aircraft have a dedicated area where the crew can rest.
On the 787 Dreamliner, the Overhead Flight Crew Rest is located above first class. Accessed by a secret door, it gives way to two beds, which are furnished with anything from a blanket to first-class bedding, depending on the airline.
The isolation of the OFCR means that it is quiet, dark and has the facility to control the temperature. All in all, it makes for a great place to get some quality sleep in preparation for landing.
As mentioned before, the Autopilot is great for keeping the wings level but will only do what the pilots instruct it to do. This normally involves following the planned route. This is fine for the most part, but when there are thunderstorms ahead, the pilots need to take action.
As commercial pilots, our main role is to keep you the passenger safe and comfortable. Staying clear of thunderstorms is part of this remit. Most, if not all, passenger aircraft have a weather radar system. This sends out electronic pulses which bounce back off water droplets (clouds) ahead. The system then picks these return signals up and displays them on our screens.
Using our theoretical knowledge and experience, we then have to decide on the best route to keep us clear of the weather. This may just be a small jink left or right to avoid an isolated storm cell. If we can, we’ll always try to avoid flying downwind of a thunderstorm. As the wind whips around the cell, it can create turbulence in this downwind area.
However, in equatorial areas, there can be bands of thunderstorms hundreds of miles wide. With these clouds often reaching 50,000 feet, going over the top is not an option. The only course of action is to pick a route around them.
As part of the preflight briefing, we will study the weather charts to see if this eventuality is likely. If so, we will carry extra fuel to allow us to safely deviate around the storms, even if it’s by adding hundreds of miles to the route.
In my previous article on fuel, I explained that a long-haul aircraft may depart with around 70 tonnes of fuel in its tanks. When the flight takes off, there is an optimum altitude at which the aircraft will fly for its weight.
As the flight progresses, fuel is burned by the engines, which reduces the weight of the aircraft. As the fuel on board reduces, the lift available becomes greater than the weight, so the aircraft is able to climb to altitudes where the engines are more efficient.
So, as the aircraft gets lighter, we can request from ATC that we climb to a higher altitude. This is why on a long flight you may start at 35,000 feet, a few hours later climb to 37,000 feet and then some hours later climb to 39,000 feet.
As the flight nears the destination, it’s time for the pilots to start thinking about the arrival. The latest weather conditions are obtained, including the runway in use and the type of approach which the crew can expect to fly.
The crew will perform a landing distance calculation for the given conditions, taking into consideration the wind speed and direction, temperature, runway length and how slippery the runway may be. Once satisfied that there is enough distance to stop safely, they will carry out an approach brief.
The aim of the brief is to ensure that all pilots in the flight deck for landing understand how they plan to fly the approach and landing. We will discuss the main threats, often referred to as the ‘6 Ts’ – Terrain, Thunderstorms, Track miles, Tail winds, Traffic and aTc.
We will identify how any of these factors could cause problems during the approach and then come up with a plan on how we will deal with them. By planning ahead, we avoid being surprised and making poor decisions in the heat of the moment.
Contrary to popular belief, pilots don’t just sit there with their feet up during the cruise as the Autopilot does all the work. Whilst the workload is not as intense as during takeoff and landing, there is still plenty to be done.
Keeping tabs on the fuel status is a core part of the cruise workload. Keeping a good situational awareness of suitable airports around the aircraft is also extremely important. As these pass behind on the route, new ones must constantly be updated.
Whilst the cruise isn't as busy as takeoff and landing, there's still plenty to be done to ensure the safety of all those on board.