How pilots operate cargo flights on passenger aircraft
With a frightening drop in passenger numbers due to the COVID-19 pandemic, airlines are having to think up new ways to keep revenue coming in. Even though very few passengers are still flying, thousands of tons of cargo still need moving to keep food on tables, drugs in hospitals and toilet paper in bathrooms. While the world has shut down, global supply chains still need to be kept running.
To do this, many airlines are using their passenger aircraft to fly freight exclusively. Some flights just use the cargo holds, others are using the space on seats and overhead lockers to load bulky, lighter items. Some aircraft, like the 787 Dreamliner, are even specialized to carry temperature-sensitive cargo such as vaccines.
From cooking our own meals to arming the emergency evacuation slides, operating a passenger aircraft as a freighter requires a considerable change of procedures from the pilots.
Transporting vaccines
The Boeing 787 Dreamliner is unique in that it can chill the forward cargo compartment to maintain an exact temperature between 4 degrees Celsius (39 Fahrenheit) and 27 degrees Celsius (81 Fahrenheit). This enables airlines to carry a whole range of cargo such as perishable and live goods, but also specialist freight, which needs to be kept at a low temperature, such as vaccines.
Vaccines are incredibly temperature sensitive and need to be kept between 2 degrees Celsius (36 F) and 8 degrees Celsius (46 F) from the point of manufacture, all the way through to being administered to the patient. Even the smallest of temperature excursions along the transport chain could result in decreased effectiveness of the vaccine.
According to the World Health Organization, vaccines for influenzas are some of the most sensitive to temperature excursions, particularly to heat. Getting too warm during the transportation process and the whole batch could become void.
Studies have shown that ineffective or degraded vaccines could be the reason for the resurgence of certain vaccine-preventable diseases in countries such as Malaysia, Pakistan and Afghanistan.
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As a result, manufacturers need a reliable logistical set up which will ensure that the drugs reach the patient at the required temperature. This isn't a problem for short-range travel where a refrigerated truck can be used, but when the journey is thousands of miles and time is of the essence, air transport is the only option.
When leaving the manufacturing plant, vaccines are packed in a specialist box along with a number of coolant packs. When they are loaded into the aircraft's cargo compartment, the pilots are informed by means of a notice to the captain -- the NOTOC.
This informs us of the temperature to which we must set the forward cargo hold. When the door closes, the air conditioning system quickly chills the hold to the desired temperature and maintains this for the entirety of the flight.
Freight in the cabin
Along with the passenger baggage, commercial flights have always carried freight in the cargo compartments. Avocados from Mexico, salmon from Scotland and mangos from India all need moving quickly to reach the consumers on the other side of the world -- fresh and ready to eat. Once again, the only way to do this is by air.
However, with the passenger seats now empty, airlines are utilizing this space in the cabin to increase the cargo-carrying capacity.
There is a weight limit of 110 lbs. for each seat to ensure that the item can be secured safely, and items are restricted by how the weight is distributed. Too tall with a too high a center of mass and there's a chance that the object could topple over the seat in front in the event of turbulence or an emergency landing.
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The freight is then secured to the seats with nets to stop it from becoming dislodged during the flight. The space in the overhead lockers can also be utilized, so long as the maximum weight restrictions are complied with.
As always, the potential of a fire in the cabin remains one of the biggest threats to the safety of the aircraft. To reduce this risk, the power to the in-flight entertainment system (IFE) is switched off. The airline may also decide to have a few flight attendants on duty to provide fire watch and firefighting cover should the need arise.
Freight in the hold
Even during normal passenger operations, airlines try to maximize any spare cargo hold capacity by carrying freight. Whatever space isn't used up by passenger baggage can be utilized to carry time-sensitive cargo. It's for this reason why aircraft such as the Boeing 777 and 787 are preferred by airlines for cargo over the A380.
On the 777 and 787, a cross-section of the aircraft shows that the fuselage is roughly split in half. The upper half is where the passengers sit and the lower half is where the cargo goes. As a result, there is roughly a 1:1 ratio of passenger space to cargo space.
However, the same cross-section of the A380 shows that the aircraft is split into three sections. The upper deck, the main deck and the cargo hold. This means that there is a 2:1 passenger to cargo space ratio. With twice the number of passenger bags to fit into the same size cargo hold, there is often not much space left for extra freight.
From the pilot's perspective, whether the cargo holds are full of all freight or a mixture of freight and passenger baggage makes very little difference. In order to carry freight safely, certain procedures must be applied. Firstly, rules on dangerous goods still apply. To keep aircraft safe, the International Air Transport Association (IATA) has strict rules on what cargo airlines can carry, how it must be packaged and where it can be loaded on the aircraft. For example, lithium-ion batteries must be kept away from oxygen generators.
For every flight, the NOTOC notifies the crew of any special items that are being carried, including any items that are covered under the IATA Dangerous Goods Regulations. Should a problem develop with the cargo during the flight, using an IATA manual we are able to use the cargo's shipping code to determine the course of action to take.
Special procedures
When operating an aircraft with no passengers, we have to make a few changes to how we configure the aircraft. These are mainly focused around reducing the risk of a fire in the cabin that would go undetected due to the absence of flight attendants.
The biggest threat of fire comes from the in-flight entertainment system and the ovens and other equipment in the galleys. As a result, the first thing we do is cut the power to the IFE system. This also removes the power from the premium seat reclining mechanism.
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Next, we ensure that the electricity in all the galleys (except the front one) is switched off. This stops the ovens, microwaves, brewers and trash compactors from being powered. Each galley has a master switch that enables all power to be removed in that galley with the flick of a single switch. We also have to ensure that there are no loose trolleys or canisters. Having bar boxes and trolleys crashing into the cabin on takeoff and landing could damage the aircraft, delaying the next departure.
In the flight deck, we remove the power to the locking system of the flight deck door. With just the pilots on board and no passengers, there is no risk of unauthorized personnel trying to access the flight deck. This means that if one pilot leaves the flight deck, there's no way that they can accidentally get locked out.
Finally, like any normal flight, we need to "arm" the doors should we need to evacuate the aircraft in an emergency. This procedure, normally carried out by the flight attendants as we push back, connects the evacuation slide in the door to the floor of the aircraft. If the door is then opened, the slide is pulled out from its stowage and inflates automatically.
However, as the likelihood is that we'd evacuate out of the front set of doors, we only arm these two.
Once airborne, one of us must then take a walk around the cabin every 30 minutes or so to ensure that nothing untoward is going on.
This walk is one of the eeriest parts of the flight. With all the cabin lights off and all the seats empty, it feels like a ghost ship. All the usual engine noises are there, just with none of the people. No smiles from passengers, no banter with the crew. A somber and sobering experience.
Cooking our own meals
When operating a 12-hour flight across the Atlantic, we'll drink a lot of coffee and will need to eat at some point. We're normally well looked after by our amazing flight attendants who keep our stomachs full and our brains caffeinated whenever we need it.
However, when we're operating cargo-only flights, there are no passengers and hence no flight attendants. So what do we do when we don't have our colleagues to help us out? The short of it is, like full-time cargo pilots, we have to fend for ourselves.
Now, I know a lot of flight attendants reading this will be laughing out loud right at this moment. There's well-established humor between pilots and flight attendants that we don't know how anything works behind the flight deck door. Well, now it's time for us to step up.
The catering company will load enough food and drink to keep even the hungriest of pilots satisfied for the duration of the flight. This will normally consist of a few hot meals, trays with salads and desserts along with a few snacks to keep us going in between.
Drinks are also loaded, normally just bottles of water, but sometimes a few cans of Coke and juices are also included. There is also enough tea and coffee to have a party in Boston.
When it's time for something to eat or drink, one of us will hop out of our seats and into the galley. With the flight deck door still open, we can still hear everything that is going on in the cockpit. Should the need arise, we can get back into our seat much quicker than we would when visiting the bathroom on a normal flight.
The aircraft technical manuals contain details of how to use the ovens and brewers. Before long, the meals are heating up in the oven, the coffee is brewed and we're ready to enjoy our self-service meal as we head toward the sunset.
Bottom line
Operating a passenger aircraft as a freight-only flight is quite a change from normal passenger operations. There's normally no flight attendants to chat with and no customers to look after. As a result, we need to change the way in which we set up the aircraft.
Reducing the threat of an inadvertent fire is the main priority, removing the power from the major cabin electrical systems takes care of this for the most part. On the flip side, making your own food and drinks brings a novel element to the flight. As the face of commercial aviation continues to evolve, airlines must adapt and change with it. Sitting still is not an option and certainly not when there are mouths to feed and lives to save.