Hi everyone,

I don't usually post but this question has been weighing on me and I thought I'd see what the opinions about it are. (If it's been repeated please let me know)

I flew on a 737 combi up to Iqaluit recently and I just thought it was such an amazing use of space. With the growing cargo operation currently enveloping the world, I would imagine the balance between cargo and pax demand on air routes will not have the same balance as before until global demand starts to normalize. Although some airlines are strategically performing cargo-only flights, would there be any possibility of doing split cargo/passenger flights? I understand the installation of a cargo door in a fuselage is quite an effort but I was thinking more if airlines kept their seat-cargo model.

I've only done minimal load sheets before and can't fully think of a reason why it would be an issue so long as seats were blocked ahead of time, cargo/pax cabins were separated, and dangerous goods weren't allowed in the cabin. Since airlines use seats for cargo storage the aisles would be clear for evacuations as well. The only complication I can come up with is the chaos of trying to offload the cargo while the aircraft is at a gate boarding/deplaning passengers and getting catered/groomed with everyone trying to access the cabin during a quick turn-around. It might also make for awkward trips for the FA's to access the rear galleys with the trolleys getting caught on the nets.

Again I'm just a novice and would like to understand if anyone knows of legal or (probably) liable implications of having mixed loads in the cabin and why airlines haven't considered this model. Or if it's just a matter of complexity to try and arrange the configuration in booking systems/load planning?

The common believe that I've seen in this forum is that the 789 and 77W are today's combi. I also read that for aircraft to be allowed to carry pax and cargo on the same deck, it requires a solid and permanent divider, not just a net. I also think that strapping boxes with nets is not a proper way to secure item on an aircraft.

The loading will be a nightmare as well since everything thing needs to be loaded by hand via a normal exit, which will also require extra staffs. Due to the non existence of a solid divider, passengers will be able to see or even sit in front of those boxes. It'll definitely creates a not very good image on the customer.

scorpiok wrote:

Since airlines use seats for cargo storage the aisles would be clear for evacuations as well. The only complication I can come up with is the chaos of trying to offload the cargo while the aircraft is at a gate boarding/deplaning passengers and getting catered/groomed with everyone trying to access the cabin during a quick turn-around. It might also make for awkward trips for the FA's to access the rear galleys with the trolleys getting caught on the nets.

You mean on days where only 70% seats are sold the remaining 30% can be used to place parcels on them?
Or do you want to remove some seats?

I believe Lufthansa ordered the B777-9X because of belly cargo capacity.
A330-300s on five hour trips also take a lot of cargo.
Anybody has a number how many tons of belly cargo modern twins can take?

The regulations on cargo carriage keep getting stricter, which is making it more difficult to certify and operate combos. Ever since the National Air 747 crash in Afghanistan concerns about cargo shifting and rigid cargo barriers have increased. There have also been inflight fires that have brought down some cargo aircraft. Between cargo barriers, smoke detection and fire suppression, the complexities of a combi are more difficult. A quick change aircraft will never likely be certified again. Combis with rigid barriers are getting more difficult to certify.

Production built combis are a bit different. Boeing had a 737-700C that is purpose built as a combi. That’s probably more feasible than mods since the structure can be designed from scratch to accommodate the regulations. I’m not saying combi conversions can’t happen. I’m saying that the regulations make the conversion and operation more expensive, which hurts the viability and profitability.

Legality... where, please?

No disrespect intended, but Iqaluit isn't representative of the broader freight market. It's lucky to get what it gets, with whatever frequency, unless the national government wants to shovel an endless and generous stream of subsidy. (The Territory government couldn't afford it.) Iqaluit, the rest of the Canadian North, Alaska... these aren't markets big enough to drive investment for a sub-type, either. As such, freight prices clear the market at a level high enough to cover lots of labor/aircraft inefficiencies that would kill FedEx -- or people do without.

trent768 wrote:

The common believe that I've seen in this forum is that the 789 and 77W are today's combi. I also read that for aircraft to be allowed to carry pax and cargo on the same deck, it requires a solid and permanent divider, not just a net. I also think that strapping boxes with nets is not a proper way to secure item on an aircraft.

The loading will be a nightmare as well since everything thing needs to be loaded by hand via a normal exit, which will also require extra staffs. Due to the non existence of a solid divider, passengers will be able to see or even sit in front of those boxes. It'll definitely creates a not very good image on the customer.

There’s no regulatory reason that Boeing couldn’t build and certify a 74M-like 77W combi with a proper main deck cargo door and a rigid divider (or the same for Airbus and a 330 or 350). Whether there’s a commercial case for that sort of aircraft is a different matter.

Cubsrule wrote:

There’s no regulatory reason that Boeing couldn’t build and certify a 74M-like 77W combi with a proper main deck cargo door and a rigid divider (or the same for Airbus and a 330 or 350). Whether there’s a commercial case for that sort of aircraft is a different matter.

Not quite. After the SAA 747 crash, the FAA put out an NPRM which really was the death knell for the combi. While not a regulation per se, it gave a look at what the FAA was looking at. The regulations made the combi extremely difficult to run at a profit because of the regulatory requirement for fire protection and detection. Plus it required a dedicated crewmember to act as a fire marshall on the main deck. Again, while nowhere near the final rules, it does give an indication of where the FAA was going. When the 744 was introduced AC purchased 2, IIRC, combis which they never took delivery of. (IIRC). But clearly, the days of the widebody combi was over.

VMCA787 wrote:

Cubsrule wrote:

There’s no regulatory reason that Boeing couldn’t build and certify a 74M-like 77W combi with a proper main deck cargo door and a rigid divider (or the same for Airbus and a 330 or 350). Whether there’s a commercial case for that sort of aircraft is a different matter.

Not quite. After the SAA 747 crash, the FAA put out an NPRM which really was the death knell for the combi. While not a regulation per se, it gave a look at what the FAA was looking at. The regulations made the combi extremely difficult to run at a profit because of the regulatory requirement for fire protection and detection. Plus it required a dedicated crewmember to act as a fire marshall on the main deck. Again, while nowhere near the final rules, it does give an indication of where the FAA was going. When the 744 was introduced AC purchased 2, IIRC, combis which they never took delivery of. (IIRC). But clearly, the days of the widebody combi was over.

My point was simply that if money is no object, a compliant combi can be built and certified.

Cubsrule wrote:

My point was simply that if money is no object, a compliant combi can be built and certified.

And as you wrote, there was no commercial case!

VMCA787 wrote:

Cubsrule wrote:

My point was simply that if money is no object, a compliant combi can be built and certified.

And as you wrote, there was no commercial case!

No. And I'm not really sure there was much of a commercial case for the 74M either. Certainly they were not a rousing sales success.

Sokes wrote:

scorpiok wrote:

Since airlines use seats for cargo storage the aisles would be clear for evacuations as well. The only complication I can come up with is the chaos of trying to offload the cargo while the aircraft is at a gate boarding/deplaning passengers and getting catered/groomed with everyone trying to access the cabin during a quick turn-around. It might also make for awkward trips for the FA's to access the rear galleys with the trolleys getting caught on the nets.

You mean on days where only 70% seats are sold the remaining 30% can be used to place parcels on them?
Or do you want to remove some seats?

I believe Lufthansa ordered the B777-9X because of belly cargo capacity.
A330-300s on five hour trips also take a lot of cargo.
Anybody has a number how many tons of belly cargo modern twins can take?

I imagine they can take however many tons is the normal payload for the plane, as long as it all fits. The website I linked below has United being able to haul ~60t on a 787-9.

https://www.unitedcargo.com/shipping/pr ... ppingGuide

trent768 wrote:

The common believe that I've seen in this forum is that the 789 and 77W are today's combi.

Combis work on high passenger yield at low volume and high cargo volume. With the increased range of narrowbody aircraft, new hubs (e.g., ADD), there is less need.

The A359/K and 777x are the next combis. There would be a surplus of freight capacity if airlines were running a normal schedule.


Freight is a tough market.

Lightsaber

I'm sorry but isn't this default for the ATR-72?
Pax and cargo in same level?

ojjunior wrote:

I'm sorry but isn't this default for the ATR-72?
Pax and cargo in same level?

It’s how most regional aircraft are set up . . .

This is a purely hypothetical question, but I always wondered if there are any routes in the world where a 744 Combi could hit a capacity sweet spot by completely filling the main deck with cargo, and only carrying passengers on the upper deck..say 60-70 economy seats installed?

opticalilyushin wrote:

This is a purely hypothetical question, but I always wondered if there are any routes in the world where a 744 Combi could hit a capacity sweet spot by completely filling the main deck with cargo, and only carrying passengers on the upper deck..say 60-70 economy seats installed?

I'm sure some cargo airlines like CargoLux could probably sell 60-70 seats on some of there flights out of LUX (and other cargo hubs), however, it would not be worth it. They would then have to set schedules months in advance, pay a lot of additional costs for passenger handling, would have to park at passenger terminals and pay associated fees and the list goes on! Also cargo flights often depart at unfriendly times. Too many reasons it wouldn't work, as great as it would be for AvGeeks!

opticalilyushin wrote:

This is a purely hypothetical question, but I always wondered if there are any routes in the world where a 744 Combi could hit a capacity sweet spot by completely filling the main deck with cargo, and only carrying passengers on the upper deck..say 60-70 economy seats installed?

I've often wondered the same thing. When a 744 is converted to 74Y, what do they do of the upper deck cabin? Do they keep the seats, the galleys etc? Would it be feasible (and legal) to carry pax there? After all, people do routinely travel on cargo ships as pax, why not on planes?

Weatherwatcher1 wrote:

The regulations on cargo carriage keep getting stricter, which is making it more difficult to certify and operate combos. Ever since the National Air 747 crash in Afghanistan concerns about cargo shifting and rigid cargo barriers have increased. There have also been inflight fires that have brought down some cargo aircraft. Between cargo barriers, smoke detection and fire suppression, the complexities of a combi are more difficult. A quick change aircraft will never likely be certified again. Combis with rigid barriers are getting more difficult to certify.

Production built combis are a bit different. Boeing had a 737-700C that is purpose built as a combi. That’s probably more feasible than mods since the structure can be designed from scratch to accommodate the regulations. I’m not saying combi conversions can’t happen. I’m saying that the regulations make the conversion and operation more expensive, which hurts the viability and profitability.

The National crash could not be more irrelevant to combi operations and the issue is not strength of structural barriers
... what on earth are you talking about here

Qantas16 wrote:

opticalilyushin wrote:

This is a purely hypothetical question, but I always wondered if there are any routes in the world where a 744 Combi could hit a capacity sweet spot by completely filling the main deck with cargo, and only carrying passengers on the upper deck..say 60-70 economy seats installed?

I'm sure some cargo airlines like CargoLux could probably sell 60-70 seats on some of there flights out of LUX (and other cargo hubs), however, it would not be worth it. They would then have to set schedules months in advance, pay a lot of additional costs for passenger handling, would have to park at passenger terminals and pay associated fees and the list goes on! Also cargo flights often depart at unfriendly times. Too many reasons it wouldn't work, as great as it would be for AvGeeks!

There could be a network of brokers selling itineraries and finding appropriate flights. That's how it works with ships. You tell them where and approximately when you want to go, they start looking for a ship that does the route close enough to the date. Once they've found it, they call you to ask if you're still interested. They can even offer you a slightly different destination (say, you want to go to New York, then they call you back saying: "There's nothing for New York this week but would Boston be OK for you?").

Qantas16 wrote:

would have to park at passenger terminals and pay associated fees

Passengers could go through the regular (or business) terminal and be bussed to the cargo terminal.

workhorse wrote:

opticalilyushin wrote:

This is a purely hypothetical question, but I always wondered if there are any routes in the world where a 744 Combi could hit a capacity sweet spot by completely filling the main deck with cargo, and only carrying passengers on the upper deck..say 60-70 economy seats installed?

I've often wondered the same thing. When a 744 is converted to 74Y, what do they do of the upper deck cabin? Do they keep the seats, the galleys etc? Would it be feasible (and legal) to carry pax there? After all, people do routinely travel on cargo ships as pax, why not on planes?

There is no door to secure the flight deck. There are some seats and bunks and a small galley. No cargo airlines are not going to bother carrying pax.

b747400erf wrote:

Weatherwatcher1 wrote:

The regulations on cargo carriage keep getting stricter, which is making it more difficult to certify and operate combos. Ever since the National Air 747 crash in Afghanistan concerns about cargo shifting and rigid cargo barriers have increased. There have also been inflight fires that have brought down some cargo aircraft. Between cargo barriers, smoke detection and fire suppression, the complexities of a combi are more difficult. A quick change aircraft will never likely be certified again. Combis with rigid barriers are getting more difficult to certify.

Production built combis are a bit different. Boeing had a 737-700C that is purpose built as a combi. That’s probably more feasible than mods since the structure can be designed from scratch to accommodate the regulations. I’m not saying combi conversions can’t happen. I’m saying that the regulations make the conversion and operation more expensive, which hurts the viability and profitability.

The National crash could not be more irrelevant to combi operations and the issue is not strength of structural barriers
... what on earth are you talking about here

When was the last time someone designed a rigid cargo barrier in a widebody between the passenger and freight sections? It’s added cost and essentially prohibits a quick change aircraft from being certifiable.

opticalilyushin wrote:

This is a purely hypothetical question, but I always wondered if there are any routes in the world where a 744 Combi could hit a capacity sweet spot by completely filling the main deck with cargo, and only carrying passengers on the upper deck..say 60-70 economy seats installed?

I was wondering the same for A380.

Weatherwatcher1 wrote:

b747400erf wrote:

Weatherwatcher1 wrote:

The regulations on cargo carriage keep getting stricter, which is making it more difficult to certify and operate combos. Ever since the National Air 747 crash in Afghanistan concerns about cargo shifting and rigid cargo barriers have increased. There have also been inflight fires that have brought down some cargo aircraft. Between cargo barriers, smoke detection and fire suppression, the complexities of a combi are more difficult. A quick change aircraft will never likely be certified again. Combis with rigid barriers are getting more difficult to certify.

Production built combis are a bit different. Boeing had a 737-700C that is purpose built as a combi. That’s probably more feasible than mods since the structure can be designed from scratch to accommodate the regulations. I’m not saying combi conversions can’t happen. I’m saying that the regulations make the conversion and operation more expensive, which hurts the viability and profitability.

The National crash could not be more irrelevant to combi operations and the issue is not strength of structural barriers
... what on earth are you talking about here

When was the last time someone designed a rigid cargo barrier in a widebody between the passenger and freight sections? It’s added cost and essentially prohibits a quick change aircraft from being certifiable.

The AS 737-400Cs (mid 2000s). As you said, they were a downgrade from the flexibility of the 200QC and were recently replaced by a trio of 700Fs. That being said they were a staple of flying between SEA and the state of Alaska. I had the pleasure of flying on the retirement flights, very unique experience

ILikeTrains wrote:

I imagine they can take however many tons is the normal payload for the plane, as long as it all fits. The website I linked below has United being able to haul ~60t on a 787-9.

https://www.unitedcargo.com/shipping/pr ... ppingGuide

The link is misleading, the maximum capacity of the cargo hold on the TCDS is 32005 kg forward hold, 25655 kg aft hold, and 2735 kg in the bulk.

However that is not achievable as there isn’t 60 tonnes of payload between empty weight and MZFW. The MZFW is 181.436 kg, the empty weight is greater than 121,436 kg.

They also list the 787-10 capacity as 70,319 kg, again on the TCDS it says maximum load in the forward hold is 36967 kg, 30617 kg in the aft, and 2735 in the bulk. The MZFW is 192777 kg, and we know from
Jayunited posts on other threads the actual empty weight of the UA 787-10 is 136 tonnes, which means the actual maximum payload is around 56 tonnes.

The numbers on the TCDS represent the maximum load the individual hold is certified for, it is incorrect to add these limits to establish the maximum payload.

You guys who are talking about 747 upper deck being used for pax, remember that in the currently-certified conversions, they install a bulkhead right behind the upper deck exit door, and remove the floor of the rest of the upper deck, to allow more 10 foot pallets on the main deck. And they relocate the staircase and replace it with a ladder, IIRC. A very-rough number would be that half of the 744 upper deck pax area is removed in the conversion.

workhorse wrote:

Qantas16 wrote:

opticalilyushin wrote:

This is a purely hypothetical question, but I always wondered if there are any routes in the world where a 744 Combi could hit a capacity sweet spot by completely filling the main deck with cargo, and only carrying passengers on the upper deck..say 60-70 economy seats installed?

I'm sure some cargo airlines like CargoLux could probably sell 60-70 seats on some of there flights out of LUX (and other cargo hubs), however, it would not be worth it. They would then have to set schedules months in advance, pay a lot of additional costs for passenger handling, would have to park at passenger terminals and pay associated fees and the list goes on! Also cargo flights often depart at unfriendly times. Too many reasons it wouldn't work, as great as it would be for AvGeeks!

There could be a network of brokers selling itineraries and finding appropriate flights. That's how it works with ships. You tell them where and approximately when you want to go, they start looking for a ship that does the route close enough to the date. Once they've found it, they call you to ask if you're still interested. They can even offer you a slightly different destination (say, you want to go to New York, then they call you back saying: "There's nothing for New York this week but would Boston be OK for you?").

Sure and suddenly yields are through the floor and any chance of the service being profitable is now gone.

I would mention that there are already airlines (pre-COVID) that use seat packs to fill up the last rows of the plane with cargo and have passengers at the front, though passengers still go down the back for bathroom etc. It does not require a door between cargo and passengers though presume regulations on what can be stored in the cabin are quite strict and certainly nothing dangerous.

Thanks for all the replies. My question was not aimed at all the practicalities and legalities (or probably a lack of), i just meant in the ideal world where a cargo airline owns a fleet of 744 Combis or converted pax planes, operates on a fixed schedule and there are no other issues, in theory where could they fly to with those pax and cargo capacity numbers? Luxembourg sounds quite good for longhaul routes!

Weatherwatcher1 wrote:

The regulations on cargo carriage keep getting stricter, which is making it more difficult to certify and operate combos. Ever since the National Air 747 crash in Afghanistan concerns about cargo shifting and rigid cargo barriers have increased. There have also been inflight fires that have brought down some cargo aircraft. Between cargo barriers, smoke detection and fire suppression, the complexities of a combi are more difficult. A quick change aircraft will never likely be certified again. Combis with rigid barriers are getting more difficult to certify.

Production built combis are a bit different. Boeing had a 737-700C that is purpose built as a combi. That’s probably more feasible than mods since the structure can be designed from scratch to accommodate the regulations. I’m not saying combi conversions can’t happen. I’m saying that the regulations make the conversion and operation more expensive, which hurts the viability and profitability.

The 737-700C is a convertable, not a Combi. Seating in on pallets that lock in place & can be removed to allow full cargo use. You cannot load main deck cargo & passenger seats at the same time which would make it a combi.

Commercial aviation is facing the huge challenge that many routes won't make it back as those airport-pairs will not be able to sustain non-stop flights in the current scenario.
It's up to the airlines facing those challenges to study if destinations in their network would be able to sustain service if flights are flown with combi-aircraft.
And if that's the case, be ready to make their demand for combi aircraft to A + B.
IMHO, combi conversions may have a hard time getting certification in U.S.A. and Europe, but if the market for combi aircraft may expect an increase, those strict regulations might be met by A + B and the M.R.O. offering aircraft conversions.
Would we be seeing A320 family and B737NG/MAX combi within a year? It could be a dream or a prediction.

zeke wrote:

ILikeTrains wrote:

I imagine they can take however many tons is the normal payload for the plane, as long as it all fits. The website I linked below has United being able to haul ~60t on a 787-9.

https://www.unitedcargo.com/shipping/pr ... ppingGuide

The link is misleading, the maximum capacity of the cargo hold on the TCDS is 32005 kg forward hold, 25655 kg aft hold, and 2735 kg in the bulk.

However that is not achievable as there isn’t 60 tonnes of payload between empty weight and MZFW. The MZFW is 181.436 kg, the empty weight is greater than 121,436 kg.

They also list the 787-10 capacity as 70,319 kg, again on the TCDS it says maximum load in the forward hold is 36967 kg, 30617 kg in the aft, and 2735 in the bulk. The MZFW is 192777 kg, and we know from
Jayunited posts on other threads the actual empty weight of the UA 787-10 is 136 tonnes, which means the actual maximum payload is around 56 tonnes.

The numbers on the TCDS represent the maximum load the individual hold is certified for, it is incorrect to add these limits to establish the maximum payload.

So the hard cap would be whatever the max payload is for that plane then. 56T in particular for the 787-10, I think the -9 maxes out at ~53T.

Seaboard World used to sell tickets on the upper deck of their 747 Containerships, albeit I think it was only for staff, Seaboard World customers, military etc. They even had a scheduled route, JFK to FRA, with reverse timings to a normal airline — daylight eastbound leaving New York early in the morning and landing in Frankfurt in time for a late-night schnitzel, and a red eye westbound, leaving Frankfurt at 2am and getting into New York at 5am, handy for beating the traffic on the Van Wyke Expressway into town. The product was called the Captain’s Deck and was very popular. 19 seats and one flight attendant. I wrote about it in my book Tiger 747 (Astral Horizon Press, 2017).

VMCA787 wrote:

Cubsrule wrote:

There’s no regulatory reason that Boeing couldn’t build and certify a 74M-like 77W combi with a proper main deck cargo door and a rigid divider (or the same for Airbus and a 330 or 350). Whether there’s a commercial case for that sort of aircraft is a different matter.

Not quite. After the SAA 747 crash, the FAA put out an NPRM which really was the death knell for the combi. While not a regulation per se, it gave a look at what the FAA was looking at. The regulations made the combi extremely difficult to run at a profit because of the regulatory requirement for fire protection and detection. Plus it required a dedicated crewmember to act as a fire marshall on the main deck. Again, while nowhere near the final rules, it does give an indication of where the FAA was going. When the 744 was introduced AC purchased 2, IIRC, combis which they never took delivery of. (IIRC). But clearly, the days of the widebody combi was over.

AC did operate 747-400 Combi aircraft. I flew one from LHR in 2000 or 2001.

Canadian North currently operate 737-400C in a fixed 78 seat configuration with a permanent bulkhead, while the two 737-300C aircraft are flexible combi - the options are general 120ish seats, 80 seats with a movable bulkhead, or zero seats. Seats are installed on pallets, so reconfiguration doesn’t take an age to complete. They’re more like the QC destinations.

ILikeTrains wrote:

So the hard cap would be whatever the max payload is for that plane then. 56T in particular for the 787-10, I think the -9 maxes out at ~53T.

Yes that is for any aircraft, from a little Cessna 172 to an A380.

aamd11 wrote:

VMCA787 wrote:

Cubsrule wrote:

There’s no regulatory reason that Boeing couldn’t build and certify a 74M-like 77W combi with a proper main deck cargo door and a rigid divider (or the same for Airbus and a 330 or 350). Whether there’s a commercial case for that sort of aircraft is a different matter.

Not quite. After the SAA 747 crash, the FAA put out an NPRM which really was the death knell for the combi. While not a regulation per se, it gave a look at what the FAA was looking at. The regulations made the combi extremely difficult to run at a profit because of the regulatory requirement for fire protection and detection. Plus it required a dedicated crewmember to act as a fire marshall on the main deck. Again, while nowhere near the final rules, it does give an indication of where the FAA was going. When the 744 was introduced AC purchased 2, IIRC, combis which they never took delivery of. (IIRC). But clearly, the days of the widebody combi was over.

AC did operate 747-400 Combi aircraft. I flew one from LHR in 2000 or 2001.

That’s correct and the three 747-433Cs were very unique aircraft.

Transport Canada tabled new specifications with regard to main deck cargo shortly after the loss of the SAA Combi in the Indian Ocean due to an uncontrollable main deck cargo fire. Air Canada took those specifications to Boeing who said they could build a “Combi” but with a fixed wall, separate air conditioning and electrical with enhanced smoke/fire detection. This satisfied Transport Canada and the order was placed.

After construction had started, Canada’s “arctic” airlines told Transport Canada that the new rules were unworkable and that likely air service to the arctic would stop. As air service was a life line to arctic, TC had to relent and rules were relaxed. However, AC’s three 747-433Cs had reached a point in construction that the fixed wall could not be reversed. They were odd aircraft indeed!

There were new rules though that did change. I remember one of them where every hour or so, I had to put on a nomex suit and armed with a 12 foot wand attached to a huge halon bottle, I would pick around the cargo of a 737 Combi. When newly started, the Flight Attendants were not aware and I scared the crap out of one that was bring us up some coffee! Tossing coffee and tray into the air, she went screaming to the back warning of a monster up front! (I may have made Yeti growls, but I still deny it).