Hard Landing
Hard Landing
Definition
A Hard Landing, in some regions referred to as a heavy landing, is a landing in which the manufacturer's touchdown limitation, expressed either as a rate of descent or as a 'g' loading value, has been exceeded. A hard landing has the potential to result in Loss of Control and/or aircraft damage, and will necessitate a manufacturer defined hard landing inspection.
Criteria
Almost all of us, either as pilots or as passengers, have experienced what we may have considered a less-than-ideal landing. These might have been manifested in a firm or bounced touchdown, a sudden longitudinal swing to realign the aircraft with the runway centreline, overly harsh deceleration, or even the unexpected displacement of loose articles or the deployment of some of the passenger oxygen masks. Whilst uncomfortable for most, and potentially frightening for some, these events seldom cross the threshold required to be classified as a hard landing. In some situations, such as during a landing on a contaminated runway, the firm touchdown may have been intentional.
As stated in the definition above, a hard landing is classified as the exceedance of a manufacturer limitation, which will vary by the category and purpose of the aircraft. For example, the hard landing threshold for an aircraft such as the MCDONNELL DOUGLAS F-4 Phantom, designed to land on an aircraft carrier, could be expected to be higher than that of a commercial airliner such as the MCDONNELL DOUGLAS MD-11. That said, based on certification criteria, the hard landing threshold is the same for virtually all commercial pattern aircraft and is expressed either as a touchdown 'g' loading of 2.6, or as a touchdown rate of descent exceeding 600 feet per minute (fpm), for landing weights up to the certified maximum for the aircraft type. For aircraft that are certified to conduct precautionary or emergency landings at weights above their normal landing limitation, the hard landing threshold is reduced to 1.7g or 360 fpm in the overweight condition. Whilst an exceedance of these values will trigger a mandatory hard landing inspection, many manufacturers also publish one or more cautionary thresholds at trigger values progressively less than the hard landing limit. Breaching a cautionary value will result in a supplementary inspection that is commensurate in scope with the severity of the event.
Cause
The most common cause of a hard landing is an unstable approach. Amongst other reasons, these can occur due to tailwind, a "rushed" approach, an attempt to comply with an overly demanding air traffic control clearance, adverse weather conditions or the improper use of automation. Abnormal speed or excessive rates of descent can make execution of the landing flare more difficult as the usual visual cues may be skewed or accelerated and the aircraft response to control inputs somewhat different to that normally experienced; that is, the input may cause the aircraft to balloon or, conversely, fail to arrest the descent. Gusty winds, active precipitation and reduced visibility can all make execution of the landing more difficult and can, therefore, increase the potential for a hard landing.
Prevention
There are a number of ways to help reduce the likelihood of a hard landing. Some of these are as follows:
- Ensure that a stabilised approach is flown. If the criteria for a stablised approach, as mandated in the company Operations Manual, have not been achieved by the prescribed height above runway, the approach should be abandoned and a go around initiated.
- Use manufacturer recommended landing configuration, approach speed, and speed additives appropriate to the runway available, aircraft weight, and any residual airframe icing.
- Use manufacturer recommended speed additives appropriate to the reported wind speed and gust increment.
- Execute the flare at the manufacturer recommended wheel height. Avoid an excessively high (or low) flare height.
- Avoid an extended hold off.
- In the event of a bounced landing, follow manufacturer recommendations for recovery. Baulked landing protocols may be necessary to prevent a hard landing.
Accidents and Incidents
On 4 April 2023, an Airbus A320 landing at Hat Yai was mismanaged, after a sudden change from headwind to tailwind just before the flare, leading to a gentle bounce. The almost immediate second touchdown occurred at a greater pitch than the initial touchdown and a resulting tail scrape led to other aircraft damage. The aircraft remained on the runway and taxied to stand normally. Both pilot’s responses to the situation were addressed by corresponding crew-specific and general crew training actions.
On 4 April 2022 an ATR 72-600 inbound to Hiva-Oa-Atuona in challenging but not unexpected conditions of terrain-induced turbulence encountered a sudden downdraft close to touchdown. The pilot monitoring made an unannounced pitch-up input to check descent. This was not recognised by the pilot flying who reversed the input, and a pitch disconnect resulted. A bounced runway contact was followed by a go-around and visual circuit to a successful landing on the opposite direction runway. Significant deficiencies were found in the provision of meteorological service at both Hiva-Oa-Atuona and many other airports in French Polynesia.
On 1 October 2022, a Boeing 737-800 first officer undergoing routine supervised training mishandled the touchdown at Nantes. The aircraft sustained substantial damage but there were no injuries. The potential consequences of an inexperienced first officer still undergoing line training attempting to land on the nonstandard runway profile at Nantes with little related coaching from the training captain were underestimated. The aircraft operator enhanced its management of line training, and a safety recommendation to improve operator awareness of Nantes’ nonstandard runway profile was made.
On 29 July 2023, a Boeing 767-300 first officer mismanaged the de-rotation of the nose landing gear during touchdown in benign daylight conditions at Houston Intercontinental. A hard nose landing gear bounce followed main landing gear touchdown, and a further nose landing gear bounce followed after the thrust reversers were selected with the nose landing gear airborne. This resulted in the unarmed speedbrakes deploying. A momentary third bounce then completed full touchdown, and the captain took control. On arrival on the assigned gate, significant structural damage was found to have been caused to the forward fuselage structure.
On 9 February 2024, an Airbus A300-600F bounced four times during an attempted landing at Leipzig with a significant tail strike occurring during the second bounce. This resulted in structural damage to the aircraft. A go-around and a second approach to a successful landing on an alternate runway followed, thus avoiding the damaged runway surface and debris from fuselage-runway contact. Having experienced several similar events in the same month, the aircraft operator significantly increased its pilot training focus on Hard Landing Avoidance, Bounce Recovery, Go-around Technique, and Tail Strike Avoidance in all three aircraft types operated.
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