JaggedMetalOs t1_izea3ve wrote
Reply to comment by VikKarabin in Last Boeing 747 rolls off line after half a century of production by diacewrb
Widebody twin jets are more cost effective for airlines than quad jets.
koko-jumbo t1_izealf7 wrote
It's because engine's are crazy expensive in maintenance. So having 50% of engine's and taking 70% of the load is pretty good deal for airlines
vibranium-501 t1_izelvcf wrote
But that does mean they are reducing redundancy the same way they reduce maintenance cost.
UncommercializedKat t1_izenlge wrote
Yes. But also less chances of failure. I think airplanes are required to be able to fly with one engine out, regardless of how many they have. Maybe some here can confirm.
yikesbrosef t1_izensxe wrote
Yep. Google ETOPS if you’re curious what the requirements are.
NPCwithnopurpose t1_izfk6at wrote
From a quick google search, a 747 can’t really maintain altitude with one engine, unlike twin jets. So, 50% of engines to maintain altitude in either case, but the 747 will cost more. That said, one engine providing thrust (to exclude APUs) is better than none. Also, the loss of an engine will probably just lead to an early landing anyway. The pilot just has more options when they started with 4 engines
anengineerandacat t1_izf54sm wrote
Higher complexity doesn't generally improve your reliability aspects though and whereas I don't know much about the 747 it's entirely possible the 4 engines aren't entirely independent.
They might share fuel-pumps per-wing, so if say something happened to fuel pump 1 out of 2 you might not have engines 1 & 2 while engines 3 & 4 are calmy doing their thing.
Less moving parts is generally always a good thing, and if it weren't a passenger aircraft potentially eliminating down to a single engine "might" be acceptable if the gliding capabilities were very good (much like some turbo-prop planes) and the risk of losing life was overall lower.
fjingpanda t1_izf9243 wrote
It's actually mostly because airlines are unable to fill these jumbos as regularly so they have lower utilization.
The narrowbodies/modern widebodys do have slightly lower maintenance costs, but also actually have a higher load factor since they can be filled regularly and flown more often.
Redbaron1960 t1_izfb313 wrote
I remember going to Hawaii in the early 80’s and having a whole middle row of 4 seats to myself. The flight was probably 20% full
Sixspeeddreams t1_izfe6f9 wrote
I flew on a BA A380 two weeks ago from London. The big jets are a fantastic passenger experience (so much less turbulence, a much quieter plane) but the plane was like you mentioned only 80% full. They let me sneak up to premium from coach for most of the flight since they had empty seats
SparksMurphey t1_izfi3ul wrote
Ironically, the 747 actually lasted a lot longer than they expected it to. The whole reason for the raised cockpit was to allow a hinged nose with direct cargo loading under the cockpit - the idea being that all the passenger 747s could be quickly and easily converted to cargo once supersonic airliners like Concorde made them obsolete. Except that never happened, and the 747 passenger role lingered much longer.
Nobel6skull t1_izf201f wrote
Also Moden jets are much much more fuel efficient.
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