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Air Turnback

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Category: General General
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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

  • 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.)
  • A321, vicinity London Gatwick, UK 2020 (On 26 February 2020, after difficulty starting an Airbus A321 left engine for the first flight of the day, the same difficulty recurred on the third flight followed by subsequent en-route abnormalities affecting both engines. After no fault was found during post flight maintenance investigation, similar problems occurred starting the left engine and after takeoff from Gatwick, both engines malfunctioned and a MAYDAY return followed. The continuing Investigation has already found that the engine problems were attributable to fuel system contamination following the addition of 37 times the maximum permitted dosage of Kathon biocide during prior scheduled maintenance work.)
  • 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.)
  • A320, en-route, east of Cork Ireland, 2017 (On 2 November 2017, the flight crew of an Airbus A320 climbing out of Cork detected a “strong and persistent” burning smell and after declaring a MAYDAY returned to Cork where confusing instructions from the crew resulted in a combination of the intended precautionary rapid disembarkation and an emergency evacuation using escape slides. The Investigation highlighted the necessity of clear and unambiguous communications with passengers which distinguish these two options and in particular noted the limitations in currently mandated pre flight briefings for passengers seated at over wing emergency exits.)
  • A332, vicinity Brisbane Australia, 2013 (On 21 November 2013, an A330 rejected its take off from Brisbane after an airspeed indication failure. Following maintenance intervention, a similar airspeed indication fault on the subsequent departure was reported to have been detected after V1. Once airborne, reversion to Alternate Law occurred and slat retraction failed. After an air turnback, it was discovered that the cause of both events was blockage of the No. 1 Pitot Head by a mud-dauber wasp nest which was created during the initial two hour turnround at Brisbane. Investigation of a 2014 event to a Boeing 737 at Brisbane with exactly the same causation was noted.)
  • C525, vicinity Bournemouth UK, 2019 (On 13 April 2019, an experienced Cessna 525 pilot almost lost control shortly after takeoff from Bournemouth when a recently installed performance enhancement system malfunctioned. After a six minute flight involving a potentially hazardous upset and recovery of compromised control, the turn back was successful. The Investigation found that although the pilot was unaware of the supplementary procedures supporting the modification, these did not adequately address possible failure cases. Also, certification flight tests prior to modification approval did not identify the severity of some possible failure outcomes and corresponding Safety Recommendations were made to the system manufacturer and safety regulators.)

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