VikKarabin t1_ize86m9 wrote
eli5 why?.
JaggedMetalOs t1_izea3ve wrote
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.
Hailgod t1_izefewi wrote
hub and spoke approach is getting replaced by more direct routes that carry less passenger each
Jbstargate1 t1_ize8tmy wrote
Newer models being produced?
[deleted] t1_izfelgi wrote
[deleted]
XJDenton t1_izgg6ng wrote
The massive jumbos were built to service the largest airports, when most long haul service operated on a "Hub and spoke" model. This is when the big international airports serve as a "hub" for the vast majority of incoming flights, where people would then connect on to another flight which would fly a shorter distance to the final destination. However airlines, for a number of reasons, have shifted more towards using smaller, more efficient aircraft that serve more direct routes. Larger aircraft also require bigger runways, which means they are not as flexible as smaller craft.
forrest_the_ace t1_izhl6hz wrote
They're too expensive to fly because they are hard to fill with passengers for even the most popular long haul routes. This was the original purpose of the aircraft. Many airports do not support them limiting their market. They being outclassed by significantly more efficient aircraft.
Boeing not producing them doesn't mean companies will stop flying them today. It just means that they will not fill and complete anymore orders. They are still popular aircraft for cargo, military, and some smaller roles.
ODBrewer t1_izff9gj wrote
It was cutting edge in the 60’s and 70’s but new technology has made it fade out.
Viewing a single comment thread. View all comments