On 1 March 2008 an Airbus A320 being operated by Lufthansa on a scheduled passenger flight from Munich to Hamburg experienced high and variable wind velocity on short finals in good daylight visibility and during the attempt at landing on runway 23 with a strong crosswind component from the right, a bounced contact of the left main landing gear with the runway was followed by a left wing down attitude which resulted in the left wing tip touching the ground. A rejected landing was then flown and after radar vectoring, a second approach to runway 33 was made to a successful landing. No aircraft occupants were injured but the aircraft left wing tip was found to have been damaged by the runway contact. The track of the aircraft and spot wind velocities given by ATC at key points are shown on the illustration below.
An investigation was carried out by the German BFU. It was determined that the co pilot had been PF for the attempted landing and that the AP and autothrottle had been disconnected at 940 feet agl. After the second runway contact with the left wing down, the aircraft commander took and retained control except whilst giving a passenger briefing whilst the aircraft was being positioned for the second approach. Both flight crew reported being unaware of the wing ground contact.
Contact with the runway was found to have resulted in damage to the wing tip fence, slat No. 5 and leading edge slat rail guides 11 and 12. These components were replaced before the aircraft was returned to service.
The Findings of the Investigation included the following:
Crew and flight operational aspects
- This was the first occasion on which the co-pilot had landed an Airbus A320 under such large crosswind influence.
- The weather situation with unusually strong gusts was an exceptional situation for both members of the flight crew.
- There was no basic training exercise, or simulator training and check procedure, in which real life situations could be practised.
- The workload was very high for both members of the crew during the approach to Runway 23 and go-around. At times during the approach, the co-pilot almost reached the limit of her mental reserves for further actions and decisions.
- In this instance it would have been appropriate to classify this landing as a "critical landing" within the meaning of the description given in (the Company Operations Manual) so that the Captain would have been personally tasked with making the landing as pilot flying (PF).
- During the final approach to land the tower reported the crosswind as gusting up to 47 knots, and the aircraft continued the approach. In view of the maximum crosswind demonstrated for landing, a Go-Around would have been reasonable.
Aircraft (Lateral control)
- When the left main landing gear first touched the runway, the lateral control system condition (thus) met all the requirements for the transition from Flight Mode to Ground Mode, so the system switched from lateral Flight Mode to lateral Ground Mode even though the aircraft was once again in the air.
- The aircraft was designed so that the effect of lateral controls (along the longitudinal axis) would reduce by about one half of full deflection as soon as one main landing gear touched down.
- The reduced effect of controls was not documented in the system description and was unknown to pilots or the training department.
Aircraft track before and after the Incident
(‘Böen’ = ‘Gust’)
Manuals and type certification
- The crew did not interpret the wording given in the Operations Manual instruction “The steady crosswind and gust component for take-off and landing must not exceed the values specified in (the Operations Manual) Where no gust limit is specified, gust exceeding crosswind limitations must be considered whenever judged operationally significant.” as a flight operational limit. The gusts were not viewed as a limiting factor.
- The aircraft certification method for setting the crosswind landing limits or guidelines,
respectively, permitted a method of demonstrating compliance which did not take into full account the real effect of crosswinds.
- The values for maximum crosswind demonstrated were presented differently for different types within the Airbus family (average wind speed plus gusts, average wind speed including gusts).
- The description of different crosswind landing techniques (crab-angle, sideslip or a combination) contained in flight operations documentation FCOM, FCTM, FCOM Bulletins and FOBN were not uniform and in part contradictory.
- The crosswind landing description given in FCOM was less suitable for use in very strong crosswinds, because it could result in the aircraft drifting from the runway centreline.
- There were different descriptions given in the aircraft manufacturer's flight documentation with respect to the use of rudder in crosswind conditions.
- One Flight Operation Briefing Note (FOBN) issued by the aircraft manufacturer described a technique for landing in strong crosswinds that would have been suitable for the Hamburg landing in question but it was not part of the official Operations Manuals.
- The description of the crosswind landing technique given in the Company Operations Manuals did not correspond fully with the one given by the aircraft manufacturer in the FCOM.
- There were differences between the landing techniques described the Operations Manual volumes covering ‘Aircraft Type’ and ‘Fight Training’; under strong crosswind conditions the wings low with crabbed approach technique described in the Flight Training volume would have been more suitable and was the method taught and practised in the simulator.
- The weather conditions at the time of the occurrence essentially matched those of the forecast.
- The wind conditions on the day of the occurrence were significant but not unusual.
The Investigation found that “this serious landing incident took place in the presence of a significant crosswind and immediate causes are as follows:
- The sudden left wing down attitude was not expected by the crew during the landing and resulted in contact between the wingtip and the ground.
- During the final approach to land the tower reported the crosswind as gusting up to 47 knots, and the aircraft continued the approach. In view of the maximum crosswind demonstrated for landing, a go-around would have been reasonable.”
The Investigation also found that “the following systematic causes led to this serious incident:
- The terminology maximum crosswind demonstrated for landing was not defined in the Operating Manual (OM/A) and in the Flight Crew Operating Manual (FCOM), Vol. 3, and the description given was misleading.
- The recommended crosswind landing technique was not clearly described in the aircraft standard documentation.
- The limited effect of lateral control (after a main gear touchdown) was unknown.”
During the Investigation, on 20 March 2009 the BFU issued five Safety Recommendations.
To Airbus that:
The aircraft manufacturer should take immediate steps to ensure that the landing technique most recently described (March 2009) should be incorporated in the flight operations documentation for the Airbus Types A318/A319/A320/A321. The descriptions given in FCOM, FCTM, in the FCOM Bulletins, FOBNs and all other documents should be uniform, clear and understandable without any contradictions.
Recommendation No.: 12/2009
Should it not be possible to implement recommendation 12/09 without delay for editorial reasons, or for reasons of unalterable amendment procedures for the respective flight documents, the aircraft manufacturer should inform all operators of the Airbus Types A318/A319/A320/A321 without delay and in suitable form, about the circumstances of this Serious Incident and the planned changes.
Recommendation No.: 13/2009
To Lufthansa that:
It must be ensured that the crosswind landing technique described in the Operations Manual, Part B (OM/B), Chapter 2, is the same as the instructions and descriptions given by the aircraft manufacturer. When incorporating supplements and background information that are not incorporated in the aircraft manufacturer's FCOM documentation into the description of crosswind landing techniques, the working process and an associated quality assurance (QA) procedure should be described and applied; the QA procedure should ensure plausibility and correctness of the instructions and check for the absence of instructions and descriptions that are contrary to those of the aircraft manufacturer.
Recommendation No.: 14/2009
It must be ensured that the crosswind landing technique given in the Operations Manual, Part D (OM/D) is not in conflict with that described in OM/B.
Recommendation No.: 15/2009
To the Luftfahrt-Bundesamt (German Civil Aviation Authority) that:
The Luftfahrt-Bundesamt should ensure that maximum crosswind take-off and landing speeds are set for German Air Operators. Within the context of flight operations management, all air operators should examine the handbooks provided by different aircraft manufacturers for different aircraft types and study how the handbook wording maximum crosswind demonstrated is interpreted and acted upon. When indicated, an instruction should be issued based on EU-OPS 1.015 to require that maximum crosswind values be set for crosswind take-offs and landings.
Upon the conclusion of the Investigation, the BFU issued seven further Safety Recommendations:
To Airbus that:
The aircraft manufacturer should initiate an assessment for the Aircraft Type A320 and Series with the aim that the transition logic Flight Mode/Ground Mode of the lateral control system switches into Ground Mode only if the aircraft is indeed on the ground. At the same time the updated landing technique in strong crosswind conditions should be taken into account. Furthermore, it should be ensured that such a change will not limit or impede existing system functionalities for other situations.
Recommendation No.: 01/2010
The aircraft manufacturer should, as a transitory action (until the Safety Recommendation No. 01/2010 has come into effect), amend the system descriptions for the lateral control in the flight operations documentation (FCOM, etc.) and training documentation for the Aircraft Type A320 and Series indicating that under certain circumstances limited rudder deflection may occur during landings. The explanation in the system description for the transition logic Flight Mode/Ground Mode in the FCOM “The lateral control mode does not change until the wheels are on the ground, so there is no discontinuity in the control laws.“ should be rectified.
Recommendation No.: 02/2010
The aircraft manufacturer of the Aircraft Type A320 and Series should remove the term maximum crosswind demonstrated for landing from the chapter Operating Limitations, also from the respective Flight Crew Operating Manuals (FCOM), all other flight operation instructions and information references, and place this elsewhere. The aircraft manufacturer’s flight operations documentation should incorporate the guidance that this value bears the character of ’Information’. The aircraft manufacturer should adopt a uniform presentation of maximum crosswind demonstrated for landing for the entire range of the same series of aircraft. The maximum crosswind demonstrated for landing should be described either as a dual value (average wind speed and gust) or as a single value (average wind speed including gusts). Manufacturers should make recommendations to air operators as to the suitable maximum crosswind component for landings.
Recommendation No.: 03/2010
To EASA that:
EASA should revise the Flight Test Guide Material requirements contained in the Certification Specifications CS 25.233 (Directional stability and control) and CS 25.237 (Wind velocities) to define and elucidate the term maximum crosswind demonstrated for landing. The definition adopted should make clear that this value has the character of ‘Information’, and that the same uniform terminology is adopted throughout all instruction documentation relating to flight operations. Air operators should be advised to set operational crosswind limits for their own specific operations. The value should be described either as a dual value (average wind speed and gust) or as a single value (average wind speed including gusts).
Recommendation No.: 04/2010
EASA should initiate an amendment to EU No. 859/2008 (EU-OPS) requiring special operating procedures for the operation of civil aircraft by airlines engaged in public transport activities in the presence of extreme weather situations In addition to provisions and decision guidance air operators should establish an organizational structure or unit to provide assistance to crews for pre-flight preparation and in-flight support, when faced with defined (extreme) weather conditions. If necessary, the organizational structure or unit must take the decision to cancel a flight for reasons of weather. In this context, the pilot-in-command's power of decision should remain unaffected.
Recommendation No.: 05/2010
EASA should place a contract with a suitable research institute (DLR, University or similar) to determine what measuring systems are suitable to detect the presence of near-surface gusts on airports, and how the resulting gust data and wind direction information should be processed and communicated to pilots. The results should lead to a process through which the information so obtained can be standardised and incorporated into the regulations governing air operations.
To ICAO that:
The International Civil Aviation Organisation (ICAO) should amend Annex 3 to require the incorporation of GAMET and AIRMET meteorological services in Chapter 9, to ensure the optimum provision of meteorological information to crews engaged in public transport duties for pre-flight preparation.
Recommendation No.: 07/2010
The Final Report was published in March 2010 and may be seen in full at SKYbrary bookshelf: Investigation Report 5X003-0/08 March 2010 - A320 Crosswind landing at Hamburg, 1 March 2008