Perhaps pilots can correct me if I’m wrong on the following:
Another reason planes tend to be safe is that for most of their travel time, if something goes wrong, they have time to correct it since there’s nothing around them in any direction for several kilometers. If something goes wrong while in a car, you’re nearly always close to other objects, most notably cars.
In case of complete engine failure, are nearly all airplanes designed to be able to glide down for a rough but survivable landing?
May I tack on a question related to airplane safety?
Which is most dangerous, take-off or landing? Why?
Here’s a fine example, a commercial airliner that suffers a birdstrike upon lifting off from the runway. The damaged engine exhibits repeated compressor stall events (the POP-POP-POP action) until the pilot shuts the engine down at 0:33, and then calmly flies around to a trouble-free landing a few minutes later.
Mechanical reliability has been covered. As far as mid-air collisions are concerned, they are rare because the FAA mandates a certain amount of vertical and horizontal separation between planes. When you hear on the news of a “near miss,” it usually means the involved planes violated that rule by a very small amount; it’s rare for planes to get “holy shit” close in the air.
Note too, though, that even as to motor vehicles, accidents and deaths consistently continue to decrease, even as more and more cars take to the roads.
I’m pretty sure it’s a combination of the obsessive maintenance, rigorous certification of parts, and exhaustive training and certification of pilots and maintenance staff.
If we as drivers, had the level of licensing requirements that a typical commercial pilot has to have, and our cars were maintained like airliners are, accidents and breakdowns would be just as unheard of as airline crashes.
I was an aircraft mechanic for over 20 years. I did a lot of pre-flight and post-flight inspections. We had large checklists of what to inspect plus were suppose to look around at things not on the checklist.
Then every so often the aircraft were pulled into a hanger and given a really deep inspection that entailed removing panels and other parts.
Next came time change items. Certain parts of an aircraft are replaced or closely inspected based on the number of flight hours or landings and take-offs. Almost always these parts look perfectly fine.
Lets say that a mechanic found a part broken or there’s an incident in flight cause be a defective or worn part. If it’s serious enough all the same aircraft can be grounded until the part is replaced or inspected to be good. If it’s not so serious, you might have something like 180 days to inspect the entire fleet.
So on the maintenance side of the equation, things are pretty good. Of course things aren’t always perfect as many of the inspections are done on midnight shift with tired workers. Also maintenance costs are high so keeping employment costs low happens. And people make mistakes. There’s been a few crashes and other incidents due to bad maintenance.
I’m proud to say that there was never a problem with an aircraft due to something I did or something I failed to do.
Not really. There may not be any ‘objects’ i.e. other aircraft around them compared to cars, but the ground is never far away and always much more deadly. And while all aircraft can glide to some degree, the instant you lose power you start to descend and the stopwatch to find a relatively flat, clear spot starts running down very quickly. Big airliners especially, they glide only slightly better than bricks!
Take-off by far. Passengers are more scared of landing because the big hard ground is coming at you. But landing is like coasting downhill, you’re 90% there if something goes wrong. Something goes wrong on take-off you have fewer options and, more importantly, much much less time to use them.
What is the mechanism by which airlines share significant events with one another? In the nuclear industry we share Operating Experience (OPEX) bulletins. These consist of anything and everything that could potentially cause concern, or that have resulted in systemic failure, component failure, or human performance failure.
WANO - The World Association of Nuclear Operators issued 12 such bulletins in June of this year.
A 747 has four engines. It can lose one engine on takeoff and still takeoff safely. It can lose two engines and still climb (slowly) and fly just fine. If it loses 3 engines it will have difficulty climbing, but can maintain flight for a very long time and can land safely.
If it loses all four engines, it doesn’t drop like a rock. It can still glide like a glider. A 747 will glide roughly 15 km horizontally for every 1 km it loses vertically. So if you are at 10 km (roughly 32,000 feet) it can glide 150 km and land. Power for the hydraulics and instruments comes from the engines, but if all four engines fail they can use an emergency generator that basically drops down and uses the air from the plane’s movement to spin a propeller driving the generator to power essential controls and instruments.
Most other planes are similar. Not all planes have four engines of course, but a two engine plane can lose one engine on takeoff and a three engine plane can usually lose one on takeoff and lose another in flight and still land.
Here’s the wikipedia page about the famous “Gimli Glider”, a 767 that ran out of fuel due to a calculation error and glided to a landing at an unused air field. It shows that a plane losing all of its engines can still travel a fair distance and land:
In this video, a Thomson 757 loses one engine due to a bird strike (important note - a 757 only has 2 engines). Video has ATC conversations between the plane and tower and video of the plane, including the bird strike and the resulting flameout of the engine:
There was one episode of the show “Air Crash Investigations” where the plane lost one engine and became surprisingly difficult to fly. They made note on the show how unusual this was, and that normally a plane that loses an engine can be flown and landed fairly easily. What happened in this case though as that the engine broke loose (but did not come completely off of the wing) and turned sideways, creating a huge amount of drag. It would have been better if the engine had completely fallen off. Still, the plane managed to land safely.
There are a lot of good episodes of Air Crash Investigation (also called Mayday) on YouTube. If you’re interested in how airline safety works (and very occasionally fails) it’s an excellent show to check out. They go into a good amount of detail about how this stuff works.
I think that may well be the most important reason of all. Read Henry Petrowski on how failure breeds success–if you pay close attention to the causes of the failure.
Not on a 747. The engines windmilling give you enough power.
On 757 and 767, the “Ram Air Turbine” (RAT) provides hydraulic power to operate flight controls; on the 777, the RAT provides hydraulic and electrical power. But 747s don’t have a RAT.
That’s not correct. Big jets are actually quite good gliders. They have long, high aspect ratio wings for efficient flight at high altitudes. They have low drag for the same reason. Both of these characteristics are similar to gliders.
A large jetliner can have a glide ratio close to 20:1, meaning it will glide 20 miles for every mile of altitude it loses. That’s far better than most small propeller aircraft, and is within the range of training gliders. Even a 747 with its large fuselage has a glide ratio of 15:1 to 17:1, depending on the model.
A typical airliner that lost all engines at cruising altitude could be expected to glide 100 miles or more, assuming the engine failures don’t compromise aerodynamics and the pilot can find the correct glide speed for the aircraft’s weight.
I’m almost surprised things like that don’t happen more often. How many maintenance people are working on one plane at the same time? That every step of every procedure gets done right is quite a feat.
I wonder if the stats back that up. At takeoff, you’re at full power, the plane is heavy, but the window you’re trying to maneuver in has pretty wide tolerance. Landing may be like coasting downhill, but you’re trying to hit a runway that’s not much wider than the airplane, and if something goes wrong you’ve got to get those engines spooled to go around. I know of wind-shear accidents on landing (but none lately); don’t know if it’s ever brought down an airliner on takeoff.
