Why did they exist in the first place? Certainly there must have been a financial case to be made, for so configuring aircraft in that manner.

...was it just that the extensive network of Cargo Logistics operators (FedEx, UPS, DHL, etc). render the "Combi" configuration obsolete?

My guess is that Warm Bodies in Business Class are more profitable than for a substantial increase in cargo capacity. Nonetheless, for me the question, particularly with an uptick in demand for air cargo( eCommerce) could this make business sense today (probably "no" otherwise we'd see them) so are there other mitigating factors preventing this configuration from ever being seen again?

What was the business case in the first place for Combi's?

AFAIK, there are no new combis because the powers that be will no longer certify a new aircraft with cargo and pax on the same deck.

Economically, I get the feeling that given the increasing fragmentation of routes, you need more flexibility than a combi will provide. As in you don't want to be stick with the same schedule constraints for the cargo and the pax.

The current generation of airliners have quite a lot of spare capacity in the holds for cargo, especially long haul aircraft. Add to that the explosion of routes and frequencies all over the planet that has occured in the last decade or two, and the general availability of belly cargo capacity has revolutionized the air freight market.

A 77W can easily carry 20T of cargo on a 12 hour flight, on top of a full load of pax and their bags. Not quite a combi, but throw in 2 or 3 flights a day over that route, as is now common, and all of a sudden that's the equivalent of an entire mid-size freighter worth of cargo...

I can't remember the exact figure, but I know that a vast majority of the World's air freight now travels on scheduled pax flights.
Parcel carriers tend to have their own fleets, and dedicated cargo carriers take care of the remaining 'trunk' cargo routes and oversize items.

Even if they could somehow be certified, I doubt combis would bring anything to the market.

Still some COMBI"s around Africa...depends on what the client wants...still fits the UN....but it varies. Cost vs practically vs getting the job done.

The reason is the SAA crash due to a fire on the main deck. The FAA issued a NPRM which if put into place would make an existing combi and new builds extremely expensive to modify/purchase and operate. The proposal would require a main deck firefighting capability as well as a dedicated firefighter. That adds a tremendous amount of weight/costs which make the combi not very cost effective if the rule was implemented.

mmo wrote:

The reason is the SAA crash due to a fire on the main deck. The FAA issued a NPRM which if put into place would make an existing combi and new builds extremely expensive to modify/purchase and operate. The proposal would require a main deck firefighting capability as well as a dedicated firefighter. That adds a tremendous amount of weight/costs which make the combi not very cost effective if the rule was implemented.

What about the "full switch" use case?

LH used to fly their frames with PAX over the day and then do one round of freight ( mostly mail ) in the night.
sorry only in German available, use Gtranslate:
https://de.wikipedia.org/wiki/Nachtluftpost

Afair and like the A310 MRTT seating was attached to pallets.

If it were a Combi, it would have to comply with the NPRM if it was ever introduced. It would be up to LH to either run it as a F or a Pax only version if they wanted to but they would have to make the change permanent.

Aircraft are expensive to convert over to Combi’s and they are becoming a niche market anyways, as explained above, most aircraft can carry full loads of both passengers and their cargo. If airlines want to establish such a service, they will most likely fly dedicated aircraft to their respective and desired configuration. The only airlines that really need combi are the ones that fly in very remote places where no other airlines fly to, and a place that usually doesnt have a full load of passenger traffic, hence the combi which can bring much needed supplies to remote villages and fill up seats as well. If you are interested in this topic, I’d look up Nolinor Aviation or Northern Air Cargo.

Part of it is an engineering issue: look at the root chord of a 747, L-1011, and DC-10, then compare that to their length. Next, look at the A340 and 777 and do the same. Longer fuselages and higher aspect ratios mean much more underfloor cargo area, so once pax pags are accounted for, there are plenty more container positions for cargo. Modern widebodies are essentially rearranged combis: lengthen the tube, put the cargo below decks, and use the main deck for pax space, et voila.

WIederling wrote:

mmo wrote:

The reason is the SAA crash due to a fire on the main deck. The FAA issued a NPRM which if put into place would make an existing combi and new builds extremely expensive to modify/purchase and operate. The proposal would require a main deck firefighting capability as well as a dedicated firefighter. That adds a tremendous amount of weight/costs which make the combi not very cost effective if the rule was implemented.

What about the "full switch" use case?

LH used to fly their frames with PAX over the day and then do one round of freight ( mostly mail ) in the night.
sorry only in German available, use Gtranslate:
https://de.wikipedia.org/wiki/Nachtluftpost

Afair and like the A310 MRTT seating was attached to pallets.

I think Jet2 used to do that, or maybe do it still. Fly pax during the day and at night fly mail for the Royal Mail.

QF also AFAIK do cargo-only turns with some of their all-pax aircraft at night, in addition to their dedicated subsidiary and contracted freighters.

Starlionblue wrote:

AFAIK, there are no new combis because the powers that be will no longer certify a new aircraft with cargo and pax on the same deck.

Economically, I get the feeling that given the increasing fragmentation of routes, you need more flexibility than a combi will provide. As in you don't want to be stick with the same schedule constraints for the cargo and the pax.

I would actually think that there aren't enough potential operators to try to get a combi certified, either from the factory or as an STC (one would need at least 20 wide-body orders from a carrier OR 40 or so narrow-body orders). This will be interesting for an airline like KLM...the last major 747 Combi operator, which relies on combi planes to carry live main-deck cargo. However, there have been aftermarket combi conversions in the 737 Classic and 757 series, and the 777 freighter, which is really optimized for denser cargo, could take the place of the 747 combi and fly farther.

There seems to be a myth on A-net that (international) combi's are difficult or not to be certified under the current regulations.

This certainly not the case and even a future 747-8 combi can be certified under the present legal requirements :

The maindeck cargo compartment must be certified as FAA/EASA fire-Class C (identical to the lower cargo holds) , with an improved( one minute response time) fire/smoke warning installation (744combi -3 minutes warning time) , "fire proof cargo lining" , plus a " rigid 9G barrier , with compartment acces* ".

* = incl. airlock - if animal attendants are required (transport of live animals , e.g. horses), with a fire indication all animal attendants leave the maindeck ASAP , via the airlock.

"Sealing prefends entering fumes or smoke into the pax. compartment, identical to the lowerdeck cargo holds.
In case of fire and/or smoke, a slight underpressure, created in the maindeck cargo deck by the airconditioning system, will further prefend smoke from entering the pax compartment".
A " Halon knock-down" system must be installed to keep a metered constant halon concentration to suppress a maindeck fire , identical to the present 744combi.


The (carbon) rigid 9G barrier*, will be attachted to the (adapted) fuselage and can be removed (in two parts) with a configuration change. A configuration change will be more labour intensive than with current combi's (also removing the rigid barrier and cargo fire lining), but this configuration change will be only performed together with a C or D-check, like the current 744combi's

See 757-200combi. FAA certified in 2013 : http://www.precisionaircraft.com/combi/

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It all depends on your particular cargo/pax network if the combi operation may be profitable
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XAM2175 wrote:

QF also AFAIK do cargo-only turns with some of their all-pax aircraft at night, in addition to their dedicated subsidiary and contracted freighters.

I think it was Eastern Airlines that
did this in the ‘80’s with the A300
used as a lower deck cargo carrier


Then someone had the idea ‘why
not sell the empty seats and make
some extra $ ?


And that’s what they did on those
red eye flights, the fares were dirt
cheap


I don’t think these flights lasted very
long though

Max Q wrote:

XAM2175 wrote:

QF also AFAIK do cargo-only turns with some of their all-pax aircraft at night, in addition to their dedicated subsidiary and contracted freighters.

I think it was Eastern Airlines that
did this in the ‘80’s with the A300
used as a lower deck cargo carrier


Then someone had the idea ‘why
not sell the empty seats and make
some extra $ ?


And that’s what they did on those
red eye flights, the fares were dirt
cheap


I don’t think these flights lasted very
long though

The Moonlight Special. Hubbed in IAH. CF Airfreight filled the cargo hold. Passengers could check their bag for a fee but there was no guarantee that the bag would travel on their flight.

Lorenzo (Texas Air) came in and saw that the Moonlight Special was cutting into the business of a post-sham 1983 bankruptcy Continental, and moved The Moonlight Special to ORD.

ORD proved to be a major challenge for The Moonlight Special. Though there was evidence that it remained profitable, Lorenzo was intent on choking Eastern...upstreaming assets and routes to Continental; selling SystemOne for a promissory note; etc. Texas Air ended up shutting The Moonlight Special down.

Back to the original topic...the loss of the Helderberg really helped bring the combi era to an end.

As was burried in recent post, essentially new regulations require a fireproof barrier between the cargo and pax compartments. This practically means a fixed bulk-head, as opposed to a moveable one.

This fixed bulkhead makes a combi impractical because since you can’t move the bulk-head you have either the cargo in the front or the back. If you put 20,000 lbs of cargo on the front in order to balance the airplane you more or less have to have 20,000 lbs of passengers in the back. 20,000 lbs of passengers in the back is about 100 passengers worth.

With their combis Alaska put a few thousand pounds of lead in the aft cargo hold which helped a bit but it is an expensive and inefficient solution. If you had a light load of pax going to Nome for example that greatly restricted how much cargo you could carry.

That’s why the old combis are still flying around but the classic combis are mostly getting converted to pure freighters.