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Air Turnback

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Article Information
Category: General General
Content source: SKYbrary About SKYbrary
Content control: EUROCONTROL EUROCONTROL

Description

An air turnback is a situation where an aircraft returns to land at the departure aerodrome without having initially planned to do so.

The most common reason for air turnback is an emergency or abnormal situation during or shortly after take-off, the most common being engine failure. If the problem happens during acceleration, the crew might attempt to reject the take off depending on the speed and the nature of emergency. Sometimes a safer option is to get airborne and then make an approach and land. A probable complication in this case is that the aircraft's current weight may be greater than the certified maximum landing weight (MLW). If the crew opts for a turnback in this case, there are three options:

  • Make an overweight landing. The pilot in command has the right to deviate from prescribed procedures as required in an emergency situation in the interest of safety, i.e. they may choose to land even though the aircraft is heavier than the MLW if they consider this to be the safest course of action. The landing will be more challenging and require longer runway, thus increasing the chance of a runway excursion. Also, a special post-landing inspection will have to be carried out.
  • Burning the excess fuel, e.g. by entering a holding pattern. This is a safe option in many cases but if it is considered that by the time the weight is reduced below the MLW the aircraft will no longer be airworthy, or there is another urgent matter (e.g. a medical emergency) another course of action will be taken.
  • Dump fuel. This option is not available for most aircraft types and even if it is, the respective system may not have been installed on the particular aircraft. Additional restrictions may also apply, e.g. a minimum level to perform the operation or the need to reach a dedicated fuel dumping area.

Air turnback may happen during all phases of the flight, e.g. climb, cruise or even when the aircraft has reached the vicinity of the destination aerodrome (but is unable to land due to weather conditions). Any significant problem with the aircraft during the climb phase is likely to result in a turnback because of the closeness of the departure aerodrome. During the cruise, if an engine fails (or annother emergency situation arises, e.g. loss of cabin pressure), the flight crew will evaluate the situation and decide on the further course of action. Depending on the circumstances (severity of the situation, available fuel, company policy, weather, etc.), the choice may be to continue to the planned destination, to divert to the planned alternate, to land at the nearest suitable aerodrome or to return to the point of departure.

Accidents and Incidents

  • B773, Abu Dhabi UAE, 2016 (On 27 September 2016, the left engine of a Boeing 777-300 failed on takeoff from Abu Dhabi after it ingested debris resulting from tread separation from one of the nose landing gear tyres and a successful overweight return to land then followed. The Investigation found that FOD damage rather than any fault with the manufacture or re-treading of the tyre had initiated tread separation and also noted the absence of any assessment of the risk of engine damage and failure from such debris ingestion which it was noted had the potential to have affected both engines rather than just one.)
  • B764, en-route, Audincourt France, 2017 (On 23 August 2017, a Boeing 767-400ER which had departed Zurich for a transatlantic crossing experienced a problem with cabin pressurisation as the aircraft approached FL 100 and levelled off to run the applicable checklist. However, despite being unable to confirm that the pressurisation system was functioning normally, the climb was then re-commenced resulting in a recurrence of the same problem and a MAYDAY emergency descent from FL 200. The Investigation found that an engineer had mixed up which pressurisation system valve was to be de-activated before departure and that the flight crew decision to continue the climb had been risky.)
  • MA60, en route, west of Bima Indonesia, 2011 (On 12 December 2011, the crew of a Xian MA60 delayed their response to an engine fire warning until the existence of a fire had been confirmed by visual inspection and then failed to follow the memory engine shutdown drill properly so that fire continued for considerably longer than it should have. The Investigation found that an improperly tightened fuel line coupling which had been getting slowly but progressively worse during earlier flights had caused the fire. It was also concluded that the pilots' delay in responding to the fire had prolonged risk exposure and "jeopardised the safety of the flight".)
  • B789, en-route, eastern Belgium, 2017 (On 29 April 2017, a Boeing 787-9 which had just reached cruise altitude after despatch with only one main ECS available began to lose cabin pressure. A precautionary descent and PAN was upgraded to a rapid descent and MAYDAY as cabin altitude rose above 10,000 feet. The Investigation found that aircraft release to service had not been preceded by a thorough enough validation of the likely reliability of the remaining ECS system. The inaudibility of the automated announcement accompanying the cabin oxygen mask drop and ongoing issues with the quality of CVR readout from 787 crash-protected recorders was also highlighted.)
  • B752, en-route, Northern Ghana, 2009 (On 28 January 2009 the crew of a Boeing 757-200 continued takeoff from Accra Ghana despite becoming aware of an airspeed discrepancy during the take off roll. An attempt to resolve the problem failed and the consequences led to confusion as to what was happening which prompted them to declare a MAYDAY and return - successfully - to Accra. The left hand pitot probe was found to be blocked by an insect. The Investigation concluded that a low speed rejected takeoff would have been more appropriate than the continued take off in the circumstances which had prevailed.)
  • A320, Singapore, 2015 (On 16 October 2015, the unlatched fan cowl doors of the left engine on an A320 fell from the aircraft during and soon after takeoff. The one which remained on the runway was not recovered for nearly an hour afterwards despite ATC awareness of engine panel loss during takeoff and as the runway remained in use, by the time it was recovered it had been reduced to small pieces. The Investigation attributed the failure to latch the cowls shut to line maintenance and the failure to detect the condition to inadequate inspection by both maintenance personnel and flight crew.)

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