Tailwind Operations

Tailwind Operations

Definition

Tailwind Operations in fixed wing aircraft are considered to be takeoffs or landings with a performance diminishing wind component – that is, a tailwind.

Effects

Tailwind Operations have a detrimental effect on aircraft performance.

  • Take Off - The take off run will be longer and the maximum allowable take off weight for a specific runway and temperature may have to be reduced. The climb gradient will be reduced due to the higher groundspeed and could result in a CFIT accident due to inability to out clear an obstacle.
  • Approach - On approach the increased groundspeed will necessitate an increased rate of descent. Failure to compensate for these factors could easily result in an unstable approach. An unstable approach should result in a go-around.
  • Landing - The ground speed at touchdown will be greater than usual and any float tendency will result in a long landing. The stopping distance will be significantly increased due to the higher groundspeed and, in combination with a long landing, could easily result in a runway excursion.

Defences

  • Operate in accordance with Manufacturer’s Limitations: Aircraft manufacturers publish a tailwind component limit for both takeoff and landing in the AFM. In most cases, it is in the order of 10 knots but may be as high as 15 knots.
  • Accurate performance calculations must be completed for all tailwind operations. For headwind operations, the use of the wind factor is optional and regulations dictate that a maximum of 50% of the headwind component can be used. However, for tailwind operations, regulations state that the tailwind component MUST be considered in the performance calculations and that 150% of the actual tailwind component must be used.
  • Maximize Runway Performance: Use of the full length of the runway for takeoff is highly recommended. Manufacturers may prohibit reduced power takeoffs under tailwind conditions.
  • Evaluate the Risks: Obstacle clearance and climb gradients must be carefully examined. Although once airborne the rate of climb in feet/minute will not change, during tailwind operations the lift-off point will be further along the runway (thus closer to the obstacle) and, due to the higher groundspeed caused by the tailwind, the climb gradient in feet/mile will be reduced.
  • Configure Early: For approach under tailwind conditions, the groundspeed will be higher and, as a consequence, greater descent rates will be required. This will result in the requirement to configure the aircraft sooner than is normal to reduce the potential of a go-around due to an unstable approach.
  • Maintain Accurate Speed Control: Fly the appropriate speed for the aircraft configuration and weight. Increasing the Indicated Airspeed will also increase the energy that must be dissipated after touchdown and could compromise the ability to stop in the available distance.
  • Land in the Touchdown Zone: The performance calculations are generally predicated on landing distance from 50’ (which assumes a threshold crossing height of 50’, a 3 degree descent to the runway and touchdown with minimal float). If the aircraft is landed “long” due to a shallow final descent or a protracted float, the landing distance will be compromised and a runway excursion could result.
  • Optimise the Use of Stopping Devices to the Landing Distance Available: Appropriate use of all available stopping devices will help ensure that the aircraft can be safely stopped.

Contributing Factors

Air Traffic Services will often determine preferential runways based on noise abatement or traffic flow criteria and will not change the active runway until the tailwind component exceeds a predetermined value – normally in the order of 5 knots. It is up to the aircraft commander to ensure that the aircraft can be safely operated with this tailwind component. If not, the aircraft commander must request a different runway and be prepared to accept the delay that the accommodation might incur.

Operators may request or, in the case of uncontrolled aerodromes, choose to operate from an out-of-wind runway for convenience or to save time. Again, it is an aircraft commander's responsibility to ensure that the takeoff or landing can be safely conducted with the existing wind conditions. It should be noted that a tailwind has a much greater effect on a light aircraft than it does on a large commercial jet as the percentage increase in groundspeed due to the tailwind is significantly higher for the smaller aircraft.

When a circling approach is in use, there may be a significant tailwind in the descent and intermediate approach even if the landing runway is into wind.

In rapidly changing surface wind conditions associated with phenomena such as microbursts or sand storms, tailwinds may be encountered on final approach or landing and possibly without the aerodrome controllers being aware of the fact.

Solutions

Understanding the performance characteristics of the aircraft you fly is critical for safe operations under tailwind conditions. If the performance data is not available or the tailwind component exceeds the allowable limit, another runway must be used.

Accidents & Incidents

The following events involved a significant tailwind component:

On 21 November 2019, with variable cross/tailwind components prevailing, a Boeing 737-800 went around from its first ILS approach to Odesa before successfully touching down from its second. It then initially veered left off the runway before regaining it after around 550 metres with two of the three landing gear legs collapsed. An emergency evacuation followed once stopped. The Investigation attributed the excursion to inappropriate directional control inputs just before but especially after touchdown, particularly a large and rapid nosewheel steering input at 130 knots which made a skid inevitable. Impact damage was also caused to runway and taxiway lighting.

On 16 May 2013, a DHC6-300 on a domestic passenger flight made a tailwind touchdown at excessive speed in the opposite direction of the of 740 metre-long runway to the notified direction in use and, after departing the runway to one side during deceleration, re-entered the runway and attempted to take off. This failed and the aircraft breached the perimeter fence and fell into a river. The Investigation identified inappropriate actions of the aircraft commander in respect of both the initial landing and his response to the subsequent runway excursion and also cited the absence of effective CRM.

On 2 May 2016, a Boeing 737-800 veered off the 2,500 metre-long landing runway near its end at speed following a night non-precision approach flown by the Captain. It then stopped on grass having sustained damage to both the left engine and landing gear. The Investigation noted that a significant but allowable tailwind component had been present at touchdown and found that the approach had been unstable, the approach and touchdown speeds excessive and that touchdown had occurred beyond the touchdown zone after applicable operating procedures had been comprehensively ignored in the presence of a steep authority and experience gradient.

On 7 August 2020, a Boeing 737-800 making its second attempt to land at Calicut off a night ILS approach with a significant tailwind component became unstabilised and touched down approximately half way down the 2,700 metre-long wet table top runway and departed the end of it at 85 knots before continuing through the RESA and a fence and then dropping sharply onto a road. This caused the fuselage to separate into three pieces with 97 of the 190 occupants including both pilots being fatally or seriously injured and 34 others sustaining minor injuries. Significant fuel spillage occurred but there was no fire.

On 3 May 2019, a Boeing 737-800 significantly overran the wet landing runway at Jacksonville Naval Air Station at night when braking action was less than expected and ended up in shallow tidal water. The Investigation found that although the approach involved had been unstabilised and made with a significant tailwind and with only a single thrust reverser available, these factors had not been the cause of the overrun which was entirely attributable to attempting to complete a landing after touching down on a wet runway during heavy rain in conditions which then led to viscous aquaplaning.

On 7 November 2018, a Boeing 747-400F overran wet landing runway 14 at Halifax at night and was sufficiently damaged as a result of exceeding the available RESA to render it a hull loss. The Investigation attributed the overrun to a combination of factors including use of un-factored landing distance, momentary mishandling of the thrust levers just after touchdown, a pilot-caused lateral deviation diverting attention from deceleration, inadequate braking and late recognition of an approach tailwind component. Poor NOTAM presentation of runway availability also led the crew to believe that the longer and more suitable runway 25 was not available.

On 5 January 2020, a Boeing 737-800 overran the wet snow contaminated landing runway at Halifax by almost 100 metres after a touchdown zone landing and a maximum deceleration effort followed a stabilised ILS approach to a shorter runway than originally intended which also had an out of limits tailwind component and was anyway flown contrary to required tailwind speed control. The Investigation found the crew had assumed the only significant difference between the initially planned and eventually used runways was the shorter length of the latter which was judged acceptable and no new landing performance data had been accessed.

On 30 September 2017, an Airbus A320 touched down late after an ILS approach to runway 32 at Sylt with a significant tailwind component being reported and failed to stop before overrunning the end of the runway and subsequently stopped on grass 80 metres beyond it. The Investigation noted that the calculated required landing distance was close to the landing distance available, the actual approach speed was 20 knots above the calculated one and that the aircraft had floated in the flare above a wet runway. It was concluded that the runway excursion was attributable to non-performance of a go-around.

On 22 December 2009, the flight crew of an American Airlines Boeing 737-800 made a long landing at Kingston at night in heavy rain and with a significant tailwind component and their aircraft overran the end of the runway at speed and was destroyed beyond repair. There was no post-crash fire and no fatalities, but serious injuries were sustained by 14 of the 154 occupants. The accident was attributed almost entirely to various actions and inactions of the crew. Damage to the aircraft after the overrun was exacerbated by the absence of a RESA.

On 25 May 2010 an Air France Airbus A318 making an automatic landing off an ILS Cat 2 approach at Nantes experienced interference with the ILS LOC signal caused by a Boeing 737-800 which was departing from the same runway but early disconnection of the AP removed any risk of un-correctable directional control problems during the landing roll. Both aircraft were operating in accordance with their ATC clearances. Investigation attributed the conflict to the decision of TWR not to instruct the A318 to go around and because of diminished situational awareness.

On 31 July 2008, the crew of an HS125-800 attempted to reject a landing at Owatonna MN after a prior deployment of the lift dumping system but their aircraft overran the runway then briefly became airborne before crashing. The aircraft was destroyed and all 8 occupants were killed. The Investigation attributed the accident to poor crew judgement and general cockpit indiscipline in the presence of some fatigue and also considered that it was partly consequent upon the absence of any regulatory requirement for either pilot CRM training or operator SOP specification for the type of small aircraft operation being undertaken.

On 14 February 2011, a Lion Air Boeing 737-900 making a night landing at Pekanbaru overran the end of the 2240 metre long runway onto the stopway after initially normal deceleration largely attributable to the thrust reversers was followed by a poor response to applied maximum braking in the final 300 metres. Whilst performance calculations showed that a stop on the runway should have been possible, it was concluded that a combination of water patches with heavy rubber contamination had reduced the friction properties of the surface towards the end of the runway and hence the effectiveness of brake application.

On 10 June 2008, a Sudan Airways Airbus A310 made a late night touchdown at Khartoum and the actions of the experienced crew were subsequently unable to stop the aircraft, which was in service with one thrust reverser inoperative and locked out, on the wet runway. The aircraft stopped essentially intact some 215 metres beyond the runway end after overrunning on smooth ground but a fuel-fed fire then took hold which impeded evacuation and eventually destroyed the aircraft.

On 26 April 2011 a Southwest Boeing 737-700 was assessed as likely not to stop before the end of landing runway 13C at alternate Chicago Midway in daylight and was intentionally steered to the grass to the left of the runway near the end, despite the presence of a EMAS. The subsequent investigation determined that the poor deceleration was a direct consequence of a delay in the deployment of both speed brakes and thrust reverser. It was noted that the crew had failed to execute the Before Landing Checklist which includes verification of speed brake arming.

On 22 May 2011 a Britten-Norman BN2A Islander being operated by Bermudian domiciled carrier Montserrat AW on a scheduled passenger flight from Antigua to Montserrat was considered at risk of an overrun after visual positioning to a day landing on runway 28 at destination in normal ground visibility. The pilot intentionally steered the aircraft off one side of the runway to decrease the degree of potential hazard and the aircraft came to a stop beside the runway and 46 metres from its end without injuries to any of the 8 occupants or damage to the aircraft.

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