[Short Version] The Science of Landing | What Pilots Think About During Landing

Altitude 1,000 feet. A little over a minute until landing.

Even if it is a moment of relief for passengers as the 'end of the journey,' for pilots, it is the final touch of the flight—the time when they must be most alert.

Landing is the process of converting the 'kinetic energy (speed)' and 'potential energy (altitude)' accumulated during flight into 'thermal energy' using brakes, reversers, spoilers, and air resistance. Controlling the vast energy of a massive aircraft within the limits of a runway and bringing it to a complete stop—that is the essence of landing.

What is a good landing?

'A shockless landing is a good landing'
—this is half true and half a misconception. A good landing has two axes: 'safety' and 'quality'.

Safety

• No matter how smooth it is, it is meaningless if you cannot stop within the runway

• On a dry runway, it is required to be able to stop within 60% of the LDA (Landing Distance Available)

• If the touchdown G-force exceeds a certain level, maintenance inspection is mandatory

• The judgment to go around (abort landing) without hesitation if necessary

Quality

• Beyond just comfort, 'where you can exit the runway' is directly linked to punctuality

• If the brake temperature is too high, the departure of the next flight will be delayed

• Reversers (reverse thrust) consume fuel and also generate noise

Conditions that influence landing

By combining these conditions, which differ every time, pilots derive the 'optimal solution for today.'

Runway conditions

• From DRY to WET to snow/ice, braking performance decreases in stages

• On a runway covered with a water film, there is a risk of hydroplaning (a phenomenon where tires float)

Wind

• Headwind: Braking distance becomes shorter. Basically, this runway is used

• Tailwind: Braking distance becomes longer. Limit values are set for each aircraft model

• Crosswind: Limits vary depending on runway conditions and aircraft type. This is why you might think, 'That plane was able to land, so why not this one?'

Illusions

• Illusions caused by runway width

• At night, the effect of runway lights makes the runway appear to be 'floating'

• Snow-covered runways are entirely white, causing a loss of depth perception

• Illusions caused by an uphill slope

Crosswind Landing Techniques

There are three main techniques for crosswind landings, each with its own characteristics.

Crab Landing

• Approaching with the nose pointed into the wind and touching down in that orientation

• Called 'Crab' because it looks like a crab walking sideways when viewed from the ground

• Recommended for landings on slippery runways

Wing-Low Landing (Sideslip)

• Lowering the upwind wing while using the rudder to align the aircraft's axis with the runway

• More comfortable with less lateral impact, but requires precise coordination of all three flight controls

• Many passenger aircraft have bank angle limits, which restricts the amount of crosswind they can handle

Mixed

• Combining crab and wing-low techniques when crosswinds are strong

• Requires higher piloting skills, but significantly expands the range of crosswinds that can be handled

Division of Roles for Braking Systems

Airliners stop by using a combination of multiple braking systems.

Ground Spoilers

• Deploy upon touchdown to eliminate lift and ensure load on the tires

• The "first line of defense in the braking system." If these do not deploy, the effectiveness of other devices also decreases

Thrust Reversers

• Direct engine exhaust forward to decelerate

• Effectiveness is greatest at high speeds, and significant braking force cannot be expected at low speeds

• On long, dry runways, they are not "devices for stopping" but rather "devices for keeping brake temperatures down"

Wheel Brakes

• The most fundamental device for converting kinetic energy into thermal energy

• Brake energy is proportional to the square of the speed

• Anti-skid systems activate on slippery surfaces, but the braking distance still increases significantly

Landings intentionally made firmly

A "thud" landing is sometimes chosen intentionally.

• Short runways: Prioritize minimizing the flare to ensure touchdown at the targeted point

• Slippery runways: A soft touchdown delays spoiler deployment, increasing braking distance. If there is a water film, there is also a risk of hydroplaning

Judgment when a bounce (a phenomenon where the aircraft lifts off again after touchdown) occurs

• Assess the remaining runway length and energy to determine if a "re-touchdown is possible"

• In situations where you are unsure, a **go-around is the best option**

Do not hesitate to go around

When a runway is in front of you, the brain begins to process landing there as the default path. This is called Commitment to Land.

• A certain number of aviation accidents are caused by continuing an unstable approach

• The role of the Pilot Monitoring (PM) in objectively monitoring the Pilot Flying (PF) is the key to safety

• A culture where the entire cockpit understands that 'a go-around is not a failure' is the greatest line of defense

Characteristics of Haneda Airport

Haneda has four runways, each with different characteristics and difficulties.

RWY 34L (Runway A)

• The primary landing-only runway used at Haneda during northerly winds

• 'Hangar waves' (orographic turbulence) caused by adjacent hangars occur just before touchdown

• To reduce noise over the Boso Peninsula, an approach path is set that meanders over Tokyo Bay

RWY 34R (Runway C)

• The longest runway at Haneda (3,360m)

• This is the only runway capable of CAT 2/3 bad-weather landings

• In good weather, a 'highway visual' approach that circles widely over Tokyo Bay is used

RWY 22/23 (Runways B and D)

• Used during southerly winds

• In good weather, a special instrument approach method is used that is significantly offset from the runway

• It is easy to confuse the countless lights of Tokyo with runway lights, and cases of misidentification by overseas pilots have been reported

RWY 16L/16R (Runways C and A)

• Special operations limited to 3 hours between 15:00 and 19:00 during southerly winds

• A descent angle of 3.45°, which is steeper than the standard 3°, is set, resulting in an approach with a higher rate of descent than usual.

• RNP approaches utilizing GPS and FMS are the primary method, and detailed restrictions are imposed to reduce noise.

In the paid article, I provide a detailed explanation of each of these topics from the perspectives of the author's analysis, decision-making structure, actual techniques, and points of caution for Haneda Airport from an aerodynamic viewpoint. Please enjoy the detailed version as well.