Passenger and cargo aircraft look the same when flying over head. Most of the popular Boeing and Airbus passenger jets, like the 767, 747, A330, and A350, have cargo counterparts. From a distance, they all look about the same.
Passenger and freighter aircraft look similar on the outside, but they’re quite different inside.
When manufacturers build or modify aircraft, they often customize the design to meet the needs of the customer. For this reason, many variations exist. Unless otherwise noted, the following information refers to UPS aircraft, which include a few unique features.
Several Types Of Freighters
Engineers design dedicated cargo aircraft from the ground up with little or no consideration for carrying passengers. Aircraft shape and size is optimized for loading and unloading freight.
Most dedicated cargo aircraft are military transports, e.g., C-17 Globemaster, C-130 Hurcules, Antonov’s heavy-lift family.
A few military transports have crossed over to civilian cargo duty, like the Lockheed L-100 (C-130 Hercules). Delta Airlines operated a fleet of four L-100 freighters in its cargo operation from 1966 to 1974.
A cargo variant is designed for passenger service, but manufactured as a freighter, often on the same assembly line as its passenger sibling. As an example, the Boeing 767-300F cargo aircraft is nearly identical to the 767-300ER passenger jet.
Retired people-haulers often go through a conversion process to start a new life as a freighter. Converting an aircraft to a freighter can be a third of the cost of a new jet, so there is a brisk market for conversions. The economics of flying freight are different than carrying passengers; a retired passenger jet can operate profitably for years as a freighter.
Check out the process of converting a 757 passenger jet into a freighter in this video produced by Boeing:
Is it a Variant or Conversion?
Look for passenger windows.
Cargo conversions have passenger windows. Conversion facilities usually replace the clear window panes with lightweight plugs. Even when painted, the plugs are still visible (they’re easier to see on dirty airplanes).
Factory-built cargo variants do not have passenger windows; the fuselage sides are smooth. Building a freighter without windows lowers manufacturing cost and reduces the aircraft weight by hundreds of pounds.
Note: 747 freighters usually have windows in the “hump” where crew seating and rest areas are located.
Combination (or combi) aircraft are the best of both worlds. A combi is configured to carry both passengers and containerized freight. Many aircraft models have been configured as combis.
Alaska Airlines operated combi aircraft continuously from the 1940’s until 2017 when they replaced five 737-400 combis with 737-700 dedicated freighters.
The Alaska 737-400 combis held 4 standard cargo containers in the front, and 72 passengers plus two flight attendants in back. The passengers boarded from aft air stairs. Four emergency exists were located over the wings and in the rear.
Quick Change (QC) Aircraft
Another entry in the “Best of Both Worlds” department is the “Quick Change.” QC aircraft can be converted from passenger to cargo configuration in a few hours.
UPS Airlines flew passengers on a fleet of five 727-100QC aircraft from 1997 to 2001. That’s right, UPS flew human cargo (with first class service).
QC aircraft are by no means unique to UPS, but the story behind the delivery company’s passenger service is fascinating: UPS 727 Passenger Flights.
The Big Door
The most obvious exterior feature of a freighter is the big cargo door. Main cargo doors are about 11 feet (3.4 m) wide and 7-10 feet (2-3 m) tall depending on fuselage diameter. Door widths are similar on most aircraft to accommodate standard loading equipment, pallets, and containers.
Cargo doors require serious muscle power to open and close. Hydraulic actuators powered by the ship’s main hydraulic system or a dedicated electric hydraulic pump operate the doors.
For really BIG missions, Boeing 747 freighter variants have a nose door for loading extra large items like cars, trucks, and even other aircraft.
A small fleet of 747s have a tail that swings open. The Boeing “DreamLifter” is a modified 747 designed to carry large components for the 787 DreamLiner. Boeing built only four DreamLifters, so it’s always a treat to see one. DreamLifter Trivia: Only the flight deck is pressurized on this 747 conversion.
Crew Entry Door
Conversion freighters usually retain the original full-size passenger doors. Freighter variants have crew entry doors positioned to maximize usable cargo space. The doors are similar in size to their passenger counterparts.
One notable exception is the Boeing 757-200PF (Package Freighter). In order to make room for an extra cargo position, Boeing designers moved the crew entry forward several inches and reduced its size. At 48 inches tall, the door is more of a hatch; watch your head!
Main Cargo Deck
I took the photos below on a passenger 767-300ER and 767-300F freighter. The two aircraft have identical dimensions. Quite a difference!
Cargo Deck Floor System
Cargo decks have integrated rollers and ball bearing mats for fast loading and unloading. Unit Load Devices (ULDs) filled with packages are lifted onto the aircraft and easily maneuvered into position.
Floor locks hold ULDs and pallets to the floor to assure cargo won’t shift in flight. A loaded ULD can weigh thousands of pounds; that much weight shifting during takeoff or in turbulence can be catastrophic. Load crews make sure the floor locks are securely engaged on all ULDs.
Some aircraft have an automated cargo-handling system. Power-drive units (motorized wheels) built into the floor move ULDs into and out of the airplane. A small crew can load a 747 main deck in minutes with a control panel and joysticks.
Walking Tour of a Boeing 767-300F
The following video begins in the back of a Boeing 767-300F. Notice the rollers and locks integrated into the floor. At the end of the video, a crew member closes the cargo door using a control panel by the galley. It takes about a minute to close the door.
Loading, Unloading, and Sorting
UPS Airlines produced a fun time lapse of its Worldport operation in Louisville, Kentucky. Watch how ULDs are unloaded, packages sorted, and reloaded onto the aircraft.
From the pilot seats forward, a freighter is virtually identical to its passenger counterpart. The UPS 757-200PF, shown below, has new, state-of-the-art avionics.
Behind the pilot seats, a freighter is very different from its passenger sibling.
Freighters usually have extra seats available beyond what is necessary for the crew.
An additional seat on the flight deck (immediately behind the Captain and First Officer seats) is used by authorized observers, instructors, and FAA Safety Inspectors. When available, the seat can be used by off-duty pilots, maintenance technicians, and dispatchers for company required repositioning or commuting to work.
Only authorized company personal, FAA, and pilots from other airlines with reciprocal agreements can use the extra seats. Unfortunately, cargo airlines can not make these seats available to the public.
Observer seats are typically uncomfortable. Most freighters have additional, more comfortable seating options.
One of the roomiest rides is the Boeing 747. The Jumbo has plenty of room for extra seats on the upper deck behind the cockpit.
747 freighters lack the fancy staircase installed on passenger models. Permanent stairs would use valuable cargo space. Pilots access the crew areas via a folding metal ladder.
Seating in Smaller Freighters
Additional seating in the 767-300F is located on the flight deck aft of the flight crew and observer seat. The 767 observer seat (behind and between the captain and FO) is not a flight engineer position. An FAA inspector, company check pilot, or international relief officer use the seat to observe crew performance or participate as an additional crew member.
The three flip-down seats have thick cushions, recline slightly, and are reasonably comfortable for a few hours. Seat positions include air vents, reading lights, and emergency oxygen.
UPS MD-11F seating is located behind a bulkhead aft of the flight deck. The three seats are similar to narrow-body domestic business class seats.
Like the MD-11, Airbus A300-600RF seating is located behind a bulkhead. Four flip-down seats are similar to those found on the 767-300F.
Regulations require additional pilots for long flights so crew members have an opportunity to rest. Long range freighters often have beds or bunks for rest periods.
747 Sleep Rooms
In the back of the 747 crew area are two small private rooms, side-by-side, with full length beds. The sleep rooms have emergency oxygen bottles, air vents, and intercoms to communicate with the flight deck.
The MD-11 freighter has a novel rest area stored just behind the cockpit. When the aircraft reaches cruise, the crew extends the bunks. Once extended, the area has full length upper and lower bunks. Here’s a video of the rest area being configured.
767 Pilot Rest Module
UPS 767 aircraft are equipped to carry a Pilot Rest Module. The PRM is installed on flights that require more than two crew members.
The module exterior is shaped like a standard ULD. Load crews position the PRM behind the flight deck in position one. Maintenance techs connect the PRM to aircraft electric and pneumatic systems via umbilicals installed on the aircraft. The installation takes only a few minutes. The cargo access door at the rear of the flight deck provides entry to the module.
The module has two bunks with privacy curtains. Module designers angled the bunks so, during cruise, they are perfectly level. Two coach-style seats with reading lights and tray tables are also available.
Other PRM features include temperature control, reading lights, flight deck intercom, emergency oxygen bottles, portable breathing equipment, fire extinguisher, smoke detectors, and emergency lights.
The rest module is extraordinarily quiet; the perfect place to take a nap or watch a movie while not on duty. If jumpseaters are on board, they are usually welcome to utilize unused bunks or seats in the module.
All UPS aircraft have a galley (some fancier than others). Catering vendors provide crew meals on most international flights and many domestic US flights. All UPS flights are stocked with an assortment of water, juice, coffee, and tea.
The 747 galley includes refrigerated storage, drip coffee maker, hot water pot, and a programable convection/steam oven. The MD-11 galley is smaller, and does not include a coffee maker. Water for coffee/tea can be heated in a hot pot.
The 767 galley has a convection oven and hot water pot, but no refrigerator. A small pantry below the cooking unit holds food (usually packed with dry ice) and supplies. Below the pantry is storage for an Igloo-style cooler for drinks and ice. It’s a compact area, but works well, even on long flights with five people on board.
We aren’t going to hold it for 9 hours!
A300, MD-11, and 747 lavatories are just outside and behind the flight deck.
UPS 757 & 767 lavatories are on the flight deck, behind the first officer’s seat, next to the jumpseats.
The most popular question I hear is something like: “Do you guys actually use the toilet, right there in the cockpit? With the rest of the crew there?”
Well, yes. Because that’s where Boeing put it. But it’s really not that bad…
Like passenger lavatories, cargo lavs are small and have a privacy door. It’s a tight squeeze, but manageable. Going during turbulence is always an adventure.
Notice the emergency oxygen bottle next to the commode. The O2 is ready in the event of a rapid depressurization – sure beats passing out with your pants down.
Commodes flush and are serviced with the infamous airline “blue juice.”
Noise and Odor
Flight deck noise levels from outside airflow and the air conditioning system assure sonic privacy. No one can hear what’s going on in there.
It might come as a surprise that odor is not an issue. Thoughtfully designed airflow quickly removes odors from the lav and away from crew areas. Your business remains your business.
Toilet Paper: It’s stocked on every aircraft. TP is a no-go item.
Washing Up: UPS 747 lavatories have sinks with hot & cold water and liquid soap; very fancy. No running water on other UPS aircraft. All aircraft are stocked with plenty of paper towels, moist towelettes, and alcohol wipes. Plenty of options to stay clean.
There’s nothing worse than boarding an aircraft with a dirty lav (especially after parked in the hot sun). Thankfully, lavatories are cleaned and serviced when aircraft arrive. Ground crews connect the lav truck to exterior access ports to take care of our business (which then becomes their business).
If you’d like to learn more about freighter aircraft, be sure to check out these articles at NYCAviation and AeroSavvy:
- Come Along As We Cross The Pacific (NYCAviation.com)
- Airline Flying: Cargo vs Passengers (AeroSavvy.com)
- UPS 727 Passenger Flights (AeroSavvy.com)
An earlier version of this article appeared at NYCAviation.com way back in 2015.