Wow…I did not know that (and I live here).
Is there a rationale for this or is it appeasing the people who bitched a lot only to screw over some people who haven’t bitched because it was not a problem for them?
Also, I thought the pickup-sticks runways were to be able to have options for takeoff and landings based on the wind. But I really do not know.
So, put another way, why pick-up stick runway configuratrions?
Aircraft like to land and take off into the wind. Higher airspeed—which is what causes the wings to lift, and the airplane to fly—with lower ground speed. Older airplanes were underpowered enough that they couldn’t readily deal with large crosswind components the way modern heavy jets can. Crosswind component shrinks the more into (or downwind) one flies, so multiple crossing runways ensure smaller crosswinds, no matter the prevailing wind at that time.
Parallel runways allow for more traffic than crossing runways. Simple as that.
ETA: Beaten by @Gray_Ghost’s succinct points.
@Whack-a-Mole
As you say pickup stick runway configs are all about taking off and landing into the wind. But there’s a backstory.
Set the Wayback Machine to the 1920s.
Airports were simply large flat areas, typically 1x1 mile or 1/2x1/2 mile that were entirely, except for a terminal building in a corner, available for landings & takeoffs. Pilots picked out which direction and where to land on each arrival based on the wind of the moment. Over time, based on the prevailing winds, ruts and hardened areas where the grass didn’t grow occurred along the predominant takeoff and landing runs.
Fast forward to the 1940s.
Dirt / grass wasn’t strong enough to support heavier, bigger airplanes, some of which even had new-fangled nosewheels. Nor was it all-weather enough; muddy fields stopped scheduled service all too often. So they simply applied asphalt to the existing pattern of beaten down worn areas and the pickup sticks airport was born.
Fast forward to the 1960s & 1970s.
Jets don’t much care about crosswinds; not nearly like DC-3s & DC-4s did. But they do need long runways, so the airports extend a half-mile or even a mile in whatever direction they can buy land. Often reorienting an existing pickup stick 10 or 20 degrees to take best advantage of whatever land they could buy, but leaving the rest intact.
Fast forward to the 1990s & 2000s.
With airline deregulation well-established, the volume of air travel explodes. A two-runway airport can’t move enough metal to satisfy the cities’ demands. And as traffic gets denser, the delicate dance to interleave arrivals and departures onto intersecting runways (whether they intersect on the ground or their arrival / departure paths intersect in the air) gets harder and harder to accomplish. Said another way, 2 intersecting strips (e.g. LGA) cost just as much to build and operate as two parallel strips the same size, but move 50% more traffic. By the 00’s nobody had the 50% capacity to waste.
Managing 2 intersecting arrival or departure streams is hard; 4 or 6 is impossible. The only way to have that many streams is to have all the runways be parallel. ATL & DFW were the prototypes, but everybody else aspires to somehow turn into that arrangement.
Fast forward to 2019 (IOW just pre-COVID).
20+ years of local wrangling at the few remaining pickup-stick airports has finally bowed to reality and dirt is being moved, concrete laid, and the pickup sticks are headed for oblivion. O’Hare is about 90% of the way there today.
As to O’Hare specifically… of the 6 runways they had when I started flying into there in 1989, 3 of them have been closed for years now. And 3 others have been built. There is still one more to (re-)build, and one more to possibly / probably shut down. But that one oddball is takeoff only; it hasn’t been landed on in a decade or more. Why not? Because its arrival path cuts across all the other parallel runways’ arrival paths.
They are also replacing substantially all the old terminals.
Here’s the O’Hare project website which is remarkably fact-free, but does have some interesting vids. Sadly they’ve taken down all the history of what they’ve done and are just breathlessly promoting what remains to be done.
The wiki has some info on the evolution:
Late add:
This ~100 pic slide show shows the whole evolution of the airfield. And a lot more besides. Highly recommended.
There was a military airfield that adjoined O’Hare. I know for years they were separate things. Have they finally merged them?
Here’s O’Hare in its earliest days:
https://i0.wp.com/airwaysmag.com/wp-content/uploads/2016/10/DouglasFactoryandRunways.jpg?w=600&ssl=1
Wiki has the history. In a nutshell …
What is now O’Hare was originally built as a military factory airfield before / during WWII. After the war the factory left and the USAF moved in. By the 1960s the airlines started moving in too and they shared the airfield with the military but had totally separate ground facilities. By the 80s when I got involved, the airlines were the vast bulk of the acreage and the air operations. There was just a small, almost vestigial, National Guard KC-135 tanker squadron and few buildings remaining in the far northeast corner of O’Hare’s footprint. On the comparatively rare occasions they flew, they still used the same runways and taxiways as the airliners. In the late 90s the civilian airport authorities pushed USAF out for good. All the military facilities were promptly removed. That area is now buried under new runways or new car parking lots.
Of interest (happened today - 11/13/20):
Article on same event:
Ouch! At least everybody reportedly got out OK.
The intended flight was about 2800 miles, so not too long for an unladen ferry flight. That implies they were not extremely heavy as these things go.
The things I noticed from the vids were that they established runway alignment rather late, maybe only 2 miles out. We’d plan for more like 8 miles unless we had a fire in the cabin.
Most big airplanes make engine-out approaches with a reduced flap setting to preserve excess performance in the event of a go-around. That results in a faster than normal landing speed, a tendency to float in the flare, and reduced aero drag once on the runway. From the vid they looked faster than typical, didn’t float much, but did seem to have less than typical landing flaps. They also landed rather long vs the ideal touchdown point. So far, much as expected.
Once on the ground, they did not slow well. The vids are fuzzy enough I can’t be sure, but I believe they did not have spoilers deployed on the wings. That’s bad for slowing in its own right and even worse greatly reduces the effectiveness of the wheel brakes as well.
They may well have had one or more hydraulic systems out and may have been left with limited or no wheel braking also. I don’t know if those engines have thrust reversers, but even if they do, they may well be hydraulically powered
Overall, uncontained engine failures are probably the most common highly dangerous mechanical failure we get. They’re still very rare. But when one does happen it’s a very large wildcard thrown into the game due to the random battle damage inflicted.
There is at least one non sequitur in the article. It claims they had climbed to 18,000 ft, but also that they landed within 2 minutes of takeoff. Those can’t both be true.
Separately, a two-minute flight time would be all but impossible; Even if the engine failed during the takeoff, you just can’t make that small a pattern. But 4 or 5 minutes is certainly doable if you stick real close to the field. Which is also consistent with the close-in turn to final we saw in the vids.
Whether such a short pattern represents unseemly haste that led to mistakes and incomplete checklists or was sound “pilot shit” given a rapidly snowballing disaster of multiple failing systems on board remains to be seen. My gut leans towards the former but we have no info on how badly damaged the airplane was. It’ll make for interesting reading when the report comes out. I’ve been very impressed with the last couple of Russian accident investigations I’ve read. Thorough, careful, and competent seemed to be the watchwords.
I thought jet engines were specifically engineered to not have uncontained engine failure (“uncontained” being the operative word)?
I remember the Qantas Flight-32 which had one. IIRC Qantas is suing Rolls Royce because it was an uncontained engine failure that came close to crashing the plane.
Can an airport remove fuel from a plan if needed?
I know some GA planes can’t take off with a full load of fuel and full cargo capacity.
So, if for some reason the plane needs to fly with a lot of cargo and needs less fuel to meet its takeoff requirements can the fuel trucks siphon fuel out of the plane? If they can do you get a credit for the fuel they took back?
Or are you just SOL and have to fly around for a awhile with no cargo to burn off fuel?
Can an airport remove fuel from a plane… 
Re AN-124 accident
This is a cut & paste from pprune.org (kind of SDMB with an aviation focus).
The pilot’s description of the incident, as quoted by Oleksiy Sokolov on ‘Mentour Pilot’:
Quote:
The second engine exploded and cut electric wires, so we lost all the electricity. And we returned to the aerodrome of departure on an airplane having a total electric failure. We lost all the communication, both intra-cockpit and with the ATC. We just gained 300m altitude at that point. We were a crew of 6, and other technical crew of 8, they were in the rear cabin. We took a decision to return to the aerodrome of departure, visually, we tried to establish visual communication but that didn’t work. We took a decision to land on RWY25, since it was a critical situation and we took a decision to land as soon as possible. Since we didn’t have a lot of altitude and excess of thrust too. There was a complete electric failure, brakes didn’t work, reverse didn’t work either since the wires were cut. The landing was soft, there was no damage during the touchdown, all the damage was due to the runway excursion. The gauges in the cockpit didn’t work, from the angle of attack we figured out the speed was about 280, it was a calculated airspeed. We haven’t even raised the flaps at that time, just raised the gears and we heard a bang. We still had control, but the electrical system failed completely.
Yikes. That incident could’ve gotten a lot uglier.
Sort of. It’s designed and tested against loss of a single fan blade. The assumed risk scenario is a bird strike. YouTube has many of these spectacular “blade-off” tests.
A failure deeper in the engine may or may not be contained. There are no guarantees. Because the engine throat gets smaller as you progress from fan through compressor to combustor, any part that breaks off is too big to fit through the the smaller layer. That tends to lead to cascading failure where, e.g. 1 first stage blade breaks off which breaks three 2nd stage blades, and by the time you’re back at the 10th or 12th stage, you’ve stripped all the stator & rotor blades for 1/4th of the circumference.
As a rule of thumb, blades themselves generally make it out the tailpipe. Uncontained failures are usually hub bursts. You’ve got a hunk of super-steel between the size of a dinner plate and a manhole cover and from 1 to 3 inches thick turning at ~20K RPM when it spontaneously disassembles into large sectors due to an existing crack. Nothing but a cocoon of inches of military armor plating is going to contain those fragments.
The other common failure mode is a bearing failure, usually the fan bearing. Over time it damages the shaft at that station and eventually the shaft parts. The fan starts moving forward as a unit, twists sideways in the cowling duct and comes apart violently. The cowling then fails in gross overload and the whole front of the engine is gone. The AN-124 failure looks like one of those to me based on what’s still hanging on the wing.
Here in the USA there is a list of about 15 severe malfunctions that require an immediate report to NTSB, like within a couple hours of landing or crashing as the case might be. Uncontained failure is one of them.
Off the top of my head here are some uncontained failure mishaps beyond the Qantas you mentioned: AAL383, DAL1288, SWA3472.
This famous recent incident was almost the same thing: SWA1380. They had a single fan blade-off event which “should” have been contained. The blade was, but contrary to engineering expectations, the forward duct & cowling came completely unglued. And those parts were energetic enough to puncture the cabin, damage flaps, and all the rest. So technically it wasn’t an uncontained engine failure, but it was an uncontained failure. There is much finger pointing between the folks who built the engine and those who built the cowling nacelle. And some concerns between FAA & Boeing. If there had not been the MAX accidents and groundings, or if this had resulted in more fatalities, IMO this would be the aviation safety cause celebre of the last couple of years.
It turns out wiki has a nice list of uncontained failures. Though this is not all of them.
As I said, they’re a very high-risk failure. But other than for the relatively large & low-speed fan there’s simply not a way to ensure every possible failure is contained at a weight and cost that’s currently acceptable. Could FAA/EASA / etc. up their game and mandate serious armor plating around the engines? Sure. That would still leave the residual hazard of parts hitting the tail. And might add high strength high mass parts to that debris field as hunks of armor break off doing their protective energy absorbing duty.
Substantially no aircraft can take off with full full tanks and “full cargo capacity”. That would be an example of silly over-engineering that simply isn’t done. Even my generic 737 with a 175K-ish max weight has roughly 10K lbs of capacity that can be fuel or payload, but not both. Said another way, if we filled the tanks and loaded the max allowed payload, we’d be 10K lbs too heavy to taxi or to take off. Something needs to be left partly empty on every flight.
As to airlines:
So called “defueling” is routine. We try hard to avoid it, but it’s occasionally necessary. So a procedurally routine operation that’s rarely used unless a real oops gets involved. mechanically, the defueler hooks his truck up to the same connector(s) used for fueling, sets a few valves and the airplane fuel pumps that normally deliver fuel to the engines are rerouted to push the fuel from the airplane tanks into the truck. Neat & sweet.
Part of the reason we don’t fuel until very close to departure time is to preserve the flexibility to adjust fuel up or down based on changing payload and weather. When it’s real skoshy we sometime leave the fuel truck hooked up to the bitter end. We account for every pound of payload after all the doors are closed. Then carefully add the last X lbs of fuel to meet our various targets without causing an exceedance.
But we also delay fueling to near departure time for another reason. Just in case we need to swap airplane B for airplane A. It would suck to have already fueled airplane B for a long haul flight departing 4 hours from now but suddenly need to swap it into a short haul flight right now because airplane A just broke. If the weights still work, we’ll just “tanker” the excess fuel to the next destination and perhaps even the one after that. We’ll waste some of it carrying the excess weight, but not much. But if the weights don’t work, and there’s no airplane C available to sidestep the problem, the excess fuel will need to be pumped out.
The removed fuel cannot be reused in an airplane. It’s pumped out of the airplane into a special tanker truck designated for contaminated fuel. Typically it gets trans-loaded into the various diesel trucks, tugs, etc. that any carrier has all over the airport. With the increasing electrification of these ground machines, this reuse will become more problematic as time goes forward.
There’s no dollar credit, but since the carrier already paid for the fuel, they just end up paying jet fuel prices for fuel the use as diesel. In fact they also pay something extra for the time and effort to remove the fuel.
As to GA:
The same processes would apply to a bizjet, although the bizjet operator won’t have a convenient ground machine to burn the contaminated fuel. But the fuel company will.
Lightplanes and avgas are similar, but the airplanes aren’t equipped with a means to pump the fuel out. So the fueling company would have to have a suction pump to pull it from tank fill ports, much like pumping or siphoning gas from a car.
Yowza! Yeah, that was time for some pilot shit. Good thing it was a sunny day.
The backup flight instruments should have continued working, but all electrics and comms out is not a happy spot. Once you have shrapnel damage, it could be anywhere and take out primary and backup systems all at once. The AN-124 was designed as a military aircraft so you’d expect they’d have tried to position boxes and route wiring & hydraulic lines to reduce the likelihood of lose-them-all failures. But any given failure can exceed any given level of counter-engineering.
UAL232 was another example of uncontained engine failure leading to shrapnel damage that trashed all the primary and backup systems simultaneously. Which did lead to a bunch of changes in FAA certification standards for service routing.
Not the “280” speed the pilot mentions is almost certainly in km/h which converts to 151 knots which is a plausible landing speed for a midweight jet.
Some additional info:
Russian forums reporting substantial electrical loss after an uncontained engine #2 failure coupled with a loss of engine #1 control, which remained on 70% thrust all way down including the landing roll, kept running after the aircraft went stand still.
So they were lucky to land in one piece. They were also lucky that it didn’t catch fire…
Why do large passenger jets seem to approach the runway in a slightly nose-up attitude and kinda float onto the runway while smaller planes (GA mostly) seem to be pointed nose down almost all the way to the runway and only flare at the last moment (and a kinda small flare at that)?
I can provide videos of this if someone wants it.
Continuing about uncontained engine failures …
AF66 was an A380 over Greenland about 3 years ago where the whole fan module detached when the fan hub came apart. This was massively uncontained, but by a stroke of luck the escaping high speed parts fanned out above & below the fuselage, not through it. So there was no collateral damage.
Just a few weeks ago the French accident investigation authority BEA released their report. Which raises some significant concerns about the metallurgy, design, and construction of engine hubs in general, not just those on this model of engine.
This Aviation Week article summarizing the BEA report is behind a paywall, but I don’t know if they have some trial subscription or free allowance to let any interested Dopers see it: