Why some landings are hard: firm landings, wet runways and crosswinds

The landing gear slams down, the overhead bins rattle, somewhere in row 23 someone lets out an “oof.” Many passengers take a touchdown like that for a blunder in the cockpit. In the vast majority of cases, that isn’t true. Why some landings are hard has solid reasons: on a wet runway, in crosswinds or on short runways, a decisive touchdown is simply the better technique. This article explains what a firm landing is, when a landing counts as technically hard and how you recognize it at the fence as a spotter.

The short answer

A landing feels hard when the aircraft comes onto the runway with a noticeable sink rate. That is mostly intentional: on a wet runway, a decisive touchdown pushes the tires through the water film; in crosswinds, it prevents the aircraft from being displaced sideways at the last moment; and on short runways, it makes sure the touchdown point is where it belongs. Pilots then talk about a firm landing – firm, but normal.

A hard landing in the technical sense is something different. It only exists when the limits set by the manufacturer for sink rate or load at touchdown are exceeded. An inspection is then mandatory. Such cases are rare – and usually far from what you perceive as “rough” in the cabin.

Firm landing and hard landing: two different things

In everyday speech, the two terms get mixed up. In aviation, they are clearly separate.

Feature	Firm landing	Hard landing
Character	noticeable, decisive touchdown	manufacturer limits exceeded
Intent	often deliberately chosen	unintended
Typical causes	wet runway, crosswind, short runway, gusts	unstable approach, sink rate too high, botched flare, wind shear
Consequences	none – normal operations	mandatory inspection per manufacturer specification
What passengers notice	a clear jolt, rattling bins	usually a very violent impact, often with rebound

The limits for a hard landing are set by the manufacturers. The safety platform SKYbrary cites, as a reference from certification, a load factor of 2.6 g or a sink rate of more than 600 feet per minute at touchdown, relating to landings up to maximum landing weight. For overweight landings – for example, on a return shortly after takeoff – considerably lower values apply, according to SKYbrary 1.7 g or 360 feet per minute. Some manufacturers additionally define more cautious thresholds above which a supplementary inspection is due, graded by the severity of the event.

Modern airliners record the values at touchdown. If the crew reports a hard landing or the data show an exceedance, maintenance takes a look. The firm landing, by contrast, appears in no report. It is everyday business.

What actually causes a hard landing

According to SKYbrary, the most common trigger is an unstable approach: too fast, too high, too steep or not cleanly aligned. Add tailwind, a rushed approach, demanding air traffic control clearances, gusty weather, precipitation and poor visibility. If speed or sink rate are not right on short final, the flare just before the ground becomes difficult. That is why there are fixed criteria for a stabilized approach – if they are not met at a certain altitude, a go-around is flown. How that works is explained in the article Go-around.

Wet runway: why firm is right here

Rain is the classic reason for a deliberately firm touchdown. The problem is called hydroplaning: the tires glide on a film of water instead of having contact with the surface. Braking effect and directional control are then missing.

SKYbrary distinguishes three forms:

• Dynamic hydroplaning: Above a certain speed, a wedge of water builds up in front of the tire and lifts it. The threshold depends on tire pressure. The well-known rule of thumb by Horne is: speed in knots equals 9 times the square root of the tire pressure in psi. For modern tires, the factor according to SKYbrary is more like 6 to 7 – at around 150 psi, hydroplaning can then already occur from about 70 knots.
• Viscous hydroplaning: On unusually smooth surfaces, a very thin film of water is enough, at any speed. Typical are touchdown zones with thick rubber deposits from thousands of landings.
• Reverted-rubber hydroplaning: A locked wheel overheats, the water beneath it turns to steam, and the tire glides on a cushion of vapor. This mainly affects braking without working anti-skid.

On runways with normal friction, hydroplaning is considered unlikely at water depths up to about 3 millimeters. In Europe, this value is also the threshold above which a runway is classified as contaminated for performance calculation. How quickly water drains depends on slope, grooving and porous surfaces.

The trick with wheel rotation

This is where the firm landing comes into play. A wheel that is still stationary at touchdown can hydroplane directly on the wedge of water in front of it. Important systems wait for exactly this signal, though: ground spoilers deploy automatically when the wheels spin up or the landing gear reports ground contact, and autobrake and anti-skid need the wheel speed. A decisive touchdown without a bounce pushes the tires through the film, brings them up to speed immediately and lets the chain of spoilers, reverse thrust and brakes start cleanly. That is exactly what SKYbrary and the Flight Safety Foundation recommend for wet runways.

Then there is the touchdown point. Anyone who floats over the runway for a long time on a wet runway to make it smooth gives away braking distance – on a surface that brakes worse anyway. An early, firm contact therefore makes double sense.

Crosswind: align, then get down

The second major cause of noticeable landings is crosswind. In crosswind, airliners usually fly the final approach in what is called a crab: the wings stay level, and the nose points somewhat into the wind so that the aircraft stays on the approach line anyway. At 30 knots of crosswind, SKYbrary cites a crab angle of about ten to twelve degrees at three to four miles from the runway.

Shortly before touchdown, this angle has to go, because the landing gear is built for rolling in the longitudinal direction. The pilot steps on the rudder, turns the longitudinal axis onto the runway centerline and keeps the wings level with the ailerons – the de-crab. It is a brief moment with large control inputs. Every second the aircraft still floats over the runway afterward gives the wind a chance to displace it sideways or lift a wing. That is why, in crosswinds, pilots prefer to touch down promptly and decisively rather than seek the perfect soft contact.

It doesn’t always work without any residual drift. If too much of it remains, the aircraft on a slippery runway may follow its nose rather than the centerline. And even a few degrees of bank bring the nacelles dangerously close to the ground on aircraft with engines under the wings. Here, too, an early, clean ground contact is the better solution. More on the technique is in the article Crosswind landings, and if you want to film such approaches, the guide Filming crosswind landings and storms helps.

Gusts and wind shear

Gusty wind makes it even more demanding. Because the wind at the moment of touchdown can differ from the last report from the tower, crews usually fly an approach with a speed additive in gusts. If a gust drops out shortly before the ground, the aircraft sinks – the result is a firm contact that the pilot did not have entirely in hand. Situations like this are a typical reason why landings are rougher overall on windy days. How turbulent air near the ground feels and why it is not critical for the aircraft is explained in Turbulence explained.

Short runway, long float: the price of the soft landing

The butter-smooth landing that makes the cabin applaud has a flip side. Anyone who drags out the flare to let the aircraft touch down gently often floats hundreds of meters down the runway. The touchdown point moves back, and the remaining braking distance gets shorter.

On many large runways, wide white bars mark the aiming point for the landing, with further markings before and after marking the touchdown zone. That is where the main landing gear ideally touches the ground. On a long, dry runway, a few hundred meters of floating is not critical. On a short, wet or downhill runway, however, it can become a problem. Runway markings and designations are explained in the article Airport runways: designations, the lights in Runway and taxiway lighting.

That is why a well-known principle applies in the industry: a good landing is one that happens at the right time, in the right place, at the right speed – not necessarily the softest.

Why it feels different in the back

Many passengers report that the same landing feels different depending on the seat. That has to do with geometry: the main landing gear sits under the wings, so roughly in the middle of the aircraft. If you sit far forward or far back, you experience the lowering of the nose and the rebound of the fuselage differently from someone over the wing. Sounds add to it: the deployment of the spoilers, the roar of reverse thrust and the rumbling over runway joints reinforce the impression that it was “hard.”

If you struggle with fear of flying, just knowing that a noticeable jolt is usually intentional often helps. You can find more background in Understanding and overcoming fear of flying and in the article Why window shades, seat backs and lighting are regulated during takeoff and landing.

Which airports are known for firm landings

Certain airports are popular among spotters for exactly such landings because wind, topography or runway length regularly challenge the crews:

• Hamburg: In westerly wind situations and autumn storms, Hamburg Airport often delivers spectacular crosswind approaches. From the Affenfelsen and the observation deck, you are close; the Hamburg guide sums up the spots.
• Madeira: Funchal Airport lies between mountains and the Atlantic and is known for demanding wind conditions. An overview of the spots, such as Pico do Facho, is given in Plane spotting on Madeira.
• Innsbruck: At Innsbruck Airport, the mountains in the Inn valley shape approach and wind. The Innsbruck observation deck is a good starting point.

Which runway is active on a given day depends on the wind. How to predict that is covered in Understanding runway direction at airports and Using Windy and other weather maps.

Reading landings: what to watch for as a spotter

From the outside, you cannot measure whether a landing was technically hard. But you can read a lot about the technique if you know what to look at.

You see the differences most clearly if you photograph landings rather than takeoffs on purpose. Which spots are better for that is explained in Landings or takeoffs?. In bad weather, the tips from Plane spotting in bad weather help.

Conclusion

A noticeable landing is not a sign of poor piloting. Usually a deliberate decision is behind it: on a wet runway, a firm touchdown brings the wheels up to speed immediately and lowers the hydroplaning risk; in crosswinds, it prevents sideways displacement; and on short runways, it secures the full braking distance. A true hard landing, by contrast, is defined by manufacturer limits, is recorded and leads to an inspection. For you as a spotter, windy and wet days are therefore often the most exciting – with crab approaches, plumes of spray and landings that show what good technique is all about.