You insinuate that freight airlines as opposed to pax airlines do not incurr monetary losses due to poor dispatch reliability or delays. This is absolutedly false and a misconception on your part. As I've been an A/C mechanic for several major pax carriers and now at Fedex, I can tell you that any delay that can be pinned on mx is taken very seriously and after all the finger pointing is over, is analysed to avoid a repeat occurance. As far as the assertion that pax airlines have to incurr the cost of disrupted passenger travel plans and cargo carriers don't have that worry is really off base. Let me say that a Fedex MD11 filled with cargo has potential revenue (so I've been told) in the millions of dollars. If that plane should last minute go out of service and a spare aircraft is unavailable to retreive the freight in time for its eventual promised "on time" delivery. Guess what, all that freight is FREE. I'd almost have to say IMHO that having good dispatch reliability from a revenue point of view is more important on a/c flying for FDX/UPS due to the potential enormous revenue loss from just 1 widebody going into a long delay or AOG situation as opposed to a horde of angry passengers. Actually both situations are highly undesireable.
As far as reliability is concerned, its difficult to compare a freight vs pax MD11 because of the number of problems that will occur in the pax version due to the complexity of the pax cabin versus a relatively empty shell hehind the cockpit door. Of all our widebodys (MD11,DC10,A300-600,A310) the MD11 has the lowest dispatch reliability but it is still very good. IMO the larger and more complex the a/c the more susceptable it becomes to problems, especially last minute ones. It has been generally getting better over time due to the improved learning curve of maint., the working out of some troublesome bugs in different systems and the steady determination to improve the a/c over the long term.
No doubt its an excellent freighter (at least from a beancounters perspective) as many worldclass airlines such as FDX,Lufthansa and UPS (so I hear) like it to carry the boxes.
The MD11 is actually a very interesting aircraft with IMO a cockpit full of contradictions. On the one hand the automation of its different subsystems is second to none. For instance the fuel system, their is no need to turn on pumps or configure crossfeed valves if the fuel sys. controller is in auto. Its all done automatically and reconfigures the pumps, valves, etc for all flight modes and abnormal conditions. The hydraulic, electrical and pneumatic/airconditioning systems are much the same way with very little pilot action required if these systems are in auto mode. By the way, you can put these different subsystems in manual and this puts you in charge.
On the other hand the cockpit still retains aileron and rudder trim knobs as opposed to electrically operated trim switches that go as far back as the 737-300.
Overall, the MD11 is a very good aicraft with good reliablity. BUT. The thing I and most mechs who work the MD11 or DC10 dislike most is working the #2 engine. This is where MDD in my opinion screwed up royally on the MD11. The two main objectives to #2 engine is opening up the cowlings and then accomplishing the task at hand. On the DC10 you needed a Makita to raise the fan cowl on the MD11 you need a heavy hydraulic handpump to pump the fan cowl open. You would have thought MDD could have improved the accessability of #2 engine (a real Achilles Heel) learning from the DC10 but that was not to be. Actually they offer an option for a built in electric pump (I think Delta took it) but we didn,t. Still, you figure a 90 million dollar jet would come with it.
You're only as good as your last departure.