If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user

Tailwind Operations

From SKYbrary Wiki

Jump to: navigation, search
Article Information
Category: Runway Excursion Runway Excursion
Content source: SKYbrary About SKYbrary
Content control: EUROCONTROL EUROCONTROL

Contents

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 IAS 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 commande 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 ommander'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.

Related Articles

Accidents & Incidents

The following events involved a significant tailwind component:

  • B738, Limoges France, 2008 (RE WX HF) (On 21 March 2008, a Boeing 737-800 being operated by Ryanair on a scheduled passenger flight from Charleroi, Belgium to Limoges carried out a daylight approach at destination followed by a landing in normal ground visibility but during heavy rain and with a strong crosswind which ended with a 50 metre overrun into mud. None of the 181 occupants were injured but both engines were damaged by ingestion of debris.)
  • CRJ7, Kanpur India, 2011 (RE HF) (On 20 July 2011, an Alliance Air CRJ 700 touched down over half way along the 9000 ft long runway at Kanpur after a stable ILS approach but with an unexpected limiting tailwind component and failed to stop before the end of the paved surface. Although an emergency evacuation was not necessary and there were no injuries, the aircraft was slightly damaged by impact with an obstruction. The subsequent investigation attributed the event to the commanders continued attempt at a landing when a late touchdown became increasingly likely.)
  • B742, Montreal Canada, 2000 (RE HF) (On 23 July 2000, a Boeing 747-200 being operated by Royal Air Maroc on a scheduled passenger flight from New York to Montreal overran the temporarily restricted available landing runway length after the aircraft failed to decelerate sufficiently during a daylight landing with normal on-ground visibility. It struck barriers at the displaced runway end before stopping 215 metres further on. Shortly before it stopped, ATC observed flames coming out of the No. 2 engine and advised the flight crew and alerted the RFFS. However, no sustained fire developed and the aircraft was undamaged except for internal damage to the No 2 engine. No emergency evacuation was deemed necessary by the aircraft commander and there were no occupant or other injuries)
  • F50, Groningen Netherlands, 2007 (RE HF) (On 18 May 2007, a Fokker 50 being operated by Belgian airline VLM on a passenger flight from Amsterdam to Groningen landed long and at excessive speed after a visual day approach to runway 05 at destination and ran off the end of the runway onto grass. None of the 14 occupants were injured and the aircraft suffered only minor damage with two runway lights being damaged.)
  • B737, Chicago Midway USA, 2005 (RE HF WX) (Aircraft made a tailwind landing on a slippery Runway 31C and ran off the end of the runway.)
  • … further results
Retrieved from "http://www.skybrary.aero/index.php/Tailwind_Operations"
Personal tools