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
- DH8A, Nuuk Greenland, 2011 (On 4 March 2011, an aircraft left the runway during a mishandled landing at Nuuk, Greenland which resulted in the collapse of the right main landing gear due to excessive 'g' loading. The landing followed an unstabilised VMC approach in challenging weather conditions. The Investigation concluded that the crew had become focussed solely on landing and that task saturation had mentally blocked any decision to go around. The aircraft commander had less than 50 hours experience on the aircraft type and had only been released from supervised line training 6 days earlier.)
- CRJ2, Barcelona Spain, 2011 (On 30 July 2011, an Air Nostrum CRJ200 continued a significantly unstable visual approach to Barcelona in the vicinity of a convective storm to a point where the aircraft commander considered that a go around would be less safe than continuing the approach. In an attempt to regain a viable vertical profile from above, sustained and very high rates of descent were flown triggering a continuous 16 seconds of EGPWS Mode 1 PULL UP Warnings which were completely ignored. The resultant very hard landing caused structural damage to the aircraft and the sole cabin crew sustained a minor injury.)
- A332, Caracas Venezuela, 2013 (On 13 April 2013, an Air France Airbus A330-200 was damaged during a hard (2.74 G) landing at Caracas after the aircraft commander continued despite the aircraft becoming unstabilised below 500 feet agl with an EGPWS ‘SINK RATE’ activation beginning in the flare. Following a superficial inspection, maintenance personnel determined that no action was required and released the aircraft to service. After take off, it was impossible to retract the landing gear and the aircraft returned. Considerable damage from the earlier landing was then found to both fuselage and landing gear which had rendered the aircraft unfit to fly.)
- A321, Fuerteventura Spain, 2016 (On 16 July 2016, an Airbus A321’s unstabilised approach at Fuerteventura during pilot line training was not discontinued and takeover of control and commencement of a go-around had occurred just before a very hard runway contact. The subsequent landing was successful but serious damage to the main landing gear was not rectified before the next flight. The Investigation found that the hard touchdown had been recorded as in excess of 3.3g and that the return flight had been “risky and unsafe” after failure of the Captain and maintenance personnel at the Operator to recognise the seriousness of the hard landing.)
- A320, Macau SAR China, 2018 (1) (On 28 August 2018, an Airbus A320 bounced touchdown in apparently benign conditions resulted in nose gear damage and debris ingestion into both engines, in one case sufficient to significantly reduce thrust. The gear could not be raised at go around and height loss with EGPWS and STALL warnings occurred when the malfunctioning engine was briefly set to idle. Recovery was followed by a MAYDAY diversion to Shenzen and an emergency evacuation. The Investigation attributed the initial hard touchdown to un-forecast severe very low level wind shear and most of the damage to the negative pitch attitude during the second post-bounce touchdown.)
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