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==Description==
 
==Description==

Revision as of 10:02, 29 January 2021

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

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

  • SU95, Moscow Sheremetyevo Russia, 2019 (On 5 May 2019, a Sukhoi RRJ-95B making a manually-flown return to Moscow Sheremetyevo after a lightning strike caused a major electrical systems failure soon after departure made a mismanaged landing which featured a sequence of three hard bounces of increasing severity. The third of these occurred with the landing gear already collapsed and structural damage and a consequential fuel-fed fire followed as the aircraft veered off the runway at speed. The subsequent evacuation was only partly successful and 41 of the 73 occupants died and 3 sustained serious injury. An Interim Report has been published.)
  • DC93, en-route, north west of Miami USA, 1996 (On 11 May 1996, the crew of a ValuJet DC9-30 were unable to keep control of their aircraft after fire broke out. The origin of the fire was found to have been live chemical oxygen generators loaded contrary to regulations. The Investigation concluded that, whilst the root cause was poor practices at SabreTech (the maintenance contractor which handed over oxygen generators in an unsafe condition), the context for this was oversight failure at successive levels - Valujet over SabreTech and the FAA over Valujet. Failure of the FAA to require fire suppression in Class 'D' cargo holds was also cited.)
  • B735, vicinity Madrid Barajas Spain, 2019 (On 5 April 2019, a Boeing 737-500 crew declared an emergency shortly after departing Madrid Barajas after problems maintaining normal lateral, vertical or airspeed control of their aircraft in IMC. After two failed attempts at ILS approaches in unexceptional weather conditions, the flight was successfully landed at a nearby military airbase. The Investigation found that a malfunction which probably prevented use of the Captain’s autopilot found before departure was not documented until after the flight but could not find a technical explanation for inability to control the aircraft manually given that dispatch without either autopilot working is permitted.)
  • AN26, vicinity Cox’s Bazar Bangladesh, 2016 (On 29 March 2016, an Antonov AN-26B which had just taken off from Cox’s Bazar reported failure of the left engine and requested an immediate return. After twice attempting to position for a landing, first in the reciprocal runway direction then in the takeoff direction with both attempts being discontinued, control was subsequently lost during further manoeuvring and the aircraft crashed. The Investigation found that the engine malfunction occurred before the aircraft became airborne so that the takeoff could have been rejected and also that loss of control was attributable to insufficient airspeed during a low height left turn.)
  • B738, vicinity Paris Orly France, 2018 (On 7 February 2018, a Boeing 737-800 experienced an airspeed mismatch during takeoff on a post maintenance positioning flight but having identified the faulty system by reference to the standby instrumentation, the intended flight was completed without further event. After the recorded defect was then signed off as “no fault found” after a failure to follow the applicable fault-finding procedure, the same happened on the next (revenue) flight but with an air turnback made. The Investigation found that the faulty sensor had been fitted at build three earlier with a contaminated component which had slowly caused sensor malfunction to develop.)
  • MD81, vicinity Stockholm Arlanda Sweden, 1991 (On 27 December 1991, an MD-81 took off after airframe ground de/anti icing treatment but soon afterwards both engines began surging and both then failed. A successful crash landing with no fatalities was achieved four minutes after take off after the aircraft emerged from cloud approximately 900 feet above terrain. There was no post-crash fire. The Investigation found that undetected clear ice on the upper wing surfaces had been ingested into both engines during rotation and initiated engine surging. Without awareness of the aircraft's automated thrust increase system, the pilot response did not control the surging and both engines failed.)

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