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In a commercial airplane, when a landing has been a bit firm, a passenger may think it was not perfect, or maybe performed by an inexperienced pilot.
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A perfect landing is seen by passengers as one where the contact with the runway is almost imperceptible. Is that true? are there other technical or regulatory explanations?
First of all, the landing should be in the touchdown zone. Often I see pilots try to achieve a very smooth landing but floating far out of the touchdown zone before touching terra firma. Then they have to brake hard and taxi of at the far end. There are no points for landing outside the touchdown zone, even if it is the smoothest landing imaginable. In many overruns, landing late is a contributing factor.
A good landing is in the touchdown zone, firm enough to quickly spin up the wheels (and prevent wear by smearing rubber over hundreds of feet), and not so hard that it bounces up again. In calm winds, that can be very smooth, cross wind and wet / contaminated runways require a bit more of firm landing.
Hard landings1 can occur due to turbulence (wind shifts), upslope of the runway or when the air density above the runway is lower due to heating (typically in calm winds, with sun heating the runway surface)
So a hard landing is not necessarily an indication of pilot inexperience. However, some of the hardest landing I have ever experienced were when I joined in a training flight where new airline pilots were practicing landings in a Boeing 737 for the first time after their simulator training. I wouldn't be surprised if the runway was dented :-)
1Hard landing is used as a colloquial term here, not in the context of EASA CS 25 §473. See this answer for that context.
A perfect landing is seen as one where the contact with the runway is almost imperceptible.
No, the perfect landing is firm. The aircraft should touch down with a not strong, but still perceptible jolt. The reasons are:
the wheels take longer to spin up I've always wondered if the wheels are spinning before touchdown. And if not, why. Can the manufacturers put little wings on the wheels to get them spinning via airflow? Is that a bad idea for some reason?
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Jun 28, 2016 at 15:51
are there other technical or regulatory explanations?
A few points to add to the excellent answers already given:
Different aircraft models vary widely insofar as getting smooth landings. If you fly a lot, keep track of the aircraft type and what kind of landing you experience. Over time and many landings, you may see a difference.
In my own experience as a pilot, I found the Boeing 727-100 to be the hardest aircraft in which to get consistently good landings. Actually, I was never able to get consistently good landings in the 727. A string of, say, four landings in a row that could reasonably be described as "smooth" was rare. The joke among our pilots was that for the last six vertical feet before touchdown, it was the airplane, not the pilot, that was deciding what kind of landing it would be.
On the other hand, the easiest aircraft to get smooth landings in for me was the Boeing 747-100/200. You rarely got a landing that wouldn't be described as a good landing. Landings in which the first indication that you were down was the deployment of the speed brakes were not uncommon. When the mains were on, the speed brake handle in the cockpit would very noisily come out of its detent and travel all the way aft.
The pilot's landing currency also plays a role. A 747 pilot's day is one leg, one landing. If the pilots are trading legs, you're only going to get a landing every three days or so, maybe less. Commuter pilots on the other hand can get multiple landings every flying day. We tend to be better at doing that which we do often.
It doesn't often occur, but an aircraft configuration different than that which a pilot is used to can also affect the quality of the landing. For example, when they load 747-100/200/400 freighters they aim for a zero fuel weight c.g. of 26.6% MAC. One day due to the unique load we were carrying, the c.g. was up against the forward limits, 13% for both the zero fuel and landing c.g.s. The difference between 13% and 26.6% translates to a little over 44 inches. That meant that once the mains were down, the nose would want to fall through much more quickly than normal. I had forgotten about the forward c.g. and failed to use the necessary up elevator. The nose gear came down on the runway really hard, so hard I embarrassingly asked the flight engineer (an A&P) to inspect it.
As it relates to large aircraft, a hard landing means something very specific, defined in EASA CS 25 §473 and in its FAR equivalent, which is an event in which the aircraft design parameters may have been exceeded with compromise to its structural integrity.
The event may be reported by the pilots and/or detected by the aircraft's ECAM / AHM and possibly transmitted via ACARS. In any case, a thorough inspection will follow along with an occurrence reporting. Where deemed necessary, an internal or external investigation may be opened.
As to the causes, they are myriad. I am not going to speculate on their relative probabilities but anyone interested is free to trawl over the incident reports published by the accident investigation boards of his choice and come to their own conclusions.
In any event, in aviation a landing is either hard or not, there is no such thing as "a bit hard" (well, except on some pilots' tech log entries). There is also a number of other abnormal landing conditions which are just as if not more serious, such as nose-wheel landings, crabbed landings, etc.
A perfect landing is seen as one where the contact with the runway is almost imperceptible.
By whom? It is imperative, for reasons that have already been explained in other answers, that positive contact with the runway be achieved. Smooth landings are suboptimal and end up as a contributory factor to runway overruns.
From a passenger cabin point of view, you will know if you've experienced a hard landing by checking the weather: if it's raining luggage, it probably counts.
hard landing. I've updated my answer.
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I think you are confusing "hard" with "firm". A hard landing is one where the airplane needs a full inspection and possibly repairs, a firm landing is where the airplane is fine but the pilot's pride is damaged.
A simple way of explaining what happens in landing is that you reduce the airspeed of the airplane to the point where the wings no longer produce enough lift to keep the airplane off the ground, and therefore it settles onto the runway. If you hold the airplane too far up during the flare then it will drop much further when this point is reached, and the landing will be firmer and you may get a bounce or two. A sudden, powerful downdraft of wind when you are in the flare can drop you onto the runway surface before you intend as well.
Good landings take practice but nobody is perfect, and even very experienced pilots make jaw-juddering arrivals occasionally. Less experienced pilots will tend to make more of these than more experienced pilots, but it can happen to anyone.
A firm landing is no more an indication of pilot inexperience than rotation velocity. Different airframes have different flight characteristics, such as jets which are "Slick" or "Clean" - and as a result of this, they must literally be flown onto the runway with drastically less feathering than "Dirty" airframes such as single engine land airplanes. There are many factors which contribute to the impact moment experienced when contacting the tarmac, to include: Deflection due to flap positioning, characteristics of the airframe, speed of approach, glideslope, headwind, tailwind, quartering headwind or tailwind, whether the pilot chooses to crab into the runway or adjust his angle of bank, wind velocity at the surface, variability in wind velocity at the surface of the tarmac, variability in ground effect lift present, presence of wingtip vortices from preceding aircraft, the amount air pressure in the tires, the flexion and suspension travel in the suspension system for the landing gear (varies based on intended load), the density altitude at field level, thermal updrafts from the asphalt, any cratering or potholes in the runway, the powerplant/engine being used (Reciprocating engines are much more responsive to adjustments in rpm/power than jet engines which "Lag" input stimuli - therefore landings in reciprocating engined airframes can be softened by application of power with flaps dirty), etc. I could go on for hours - but it is important to realize: Any landing you (and the plane) walk away from is a good one. This is the great gulf of disparity between a human pilot and a Drone Operator - experience, skill, judgement, knowledge, and risk management.
Not necessarily. A 'hard' landing being a relative term can be due to a number of factors, some outside of the pilot's control.
Landing technique is going to vary depending on aircraft type, the type of landing gear fitted to the a/c, the runway conditions and local weather, specifically windspeed and direction. A 747 captain may 'grease' a properly executed landing while an F-18 pilot making a pass at the boat will slam it into the deck at 700 feet/min for a good landing as well.
And also good pilots mess up a landing every now and then.
Many airline pilots are ex-military. Landing style may be indicative of their previous experience. Navy pilots are trained to stick a landing more firmly than Air Force pilots. Such preferences may be in addition to the other technical factors cited by more experienced pilots above.
A bad landing can be due to conditions or just random factors. Even the best pilots have rocky landings, it's just they get a lot fewer of them than inexperienced pilots.
In general, though, it is more likely that a bad landing is due to inexperience or lack of skill in the pilot.
Sometimes if I notice an older, experienced captain with a much younger first officer on a commercial flight and we have a rocky landing, I think to myself, "Guess he let the co-pilot land the plane."
On an old-timey note, believe it or not, in the 1970s it was a common practice for passengers to applaud after a good landing.
I think that the landing has more to do with pilot preference.The pilot is supposed to land within a "touchdown zone" (as mentioned above) and how hard the landing is really just depends on what the pilot prefers. (most of the time anyway...) When pilots try to make light landings for the passengers they end often end up outside their preferred comfort zone and end up landing wrong anyway. Based on that info I believe that a firm landing isn't a sign of pilot inexperience.
