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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

  • 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.)
  • A320, vicinity Tallinn Estonia, 2018 (On 28 February 2018, an Airbus A320 would not rotate for a touch-and-go takeoff and flightpath control remained temporarily problematic and the aircraft briefly settled back onto the runway with the gear in transit damaging both engines. A very steep climb was then followed by an equally steep descent to 600 feet agl with an EGPWS ‘PULL UP’ activation before recovery. Pitch control was regained using manual stabiliser trim but after both engines stopped during a MAYDAY turnback, an undershoot touchdown followed. The root cause of loss of primary pitch control was determined as unapproved oil in the stabiliser actuator.)
  • S92, en-route, east of St John’s Newfoundland Canada, 2009 (On 12 March 2009, a Sikorsky S-92A crew heading offshore from St. John's, Newfoundland declared an emergency and began a return after total loss of main gear box oil pressure but lost control during an attempted ditching. The Investigation found that all oil had been lost after two main gear box securing bolts had sheared. It was noted that ambiguity had contributed to crew misdiagnosis the cause and that the ditching had been mishandled. Sea States beyond the capability of Emergency Flotation Systems and the limited usefulness of personal Supplemental Breathing Systems in cold water were identified as Safety Issues.)
  • 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.)
  • A320, vicinity Delhi India, 2017 (On 21 June 2017, an Airbus A320 number 2 engine began vibrating during the takeoff roll at Delhi after a bird strike. After continuing the takeoff, the Captain subsequently shut down the serviceable engine and set the malfunctioning one to TO/GA and it was several minutes before the error was recognised. After an attempted number 1 engine restart failed because an incorrect procedure was followed, a second attempt succeeded. By this time inattention to airspeed loss had led to ALPHA floor protection activation. Eventual recovery was followed by a return to land with the malfunctioning engine at flight idle.)
  • DH8C, vicinity Abu Dhabi UAE, 2012 (On 9 September 2012, the crew of a DHC8-300 climbing out of Abu Dhabi declared a PAN and returned after visual evidence of the right engine overheating were seen from the passenger cabin. The Investigation found that the observed signs of engine distress were due to hot gas exiting through the cavity left by non-replacement of one of the two sets of igniters on the engine after a pressure wash carried out overnight prior to the flight and that the left engine was similarly affected. The context for the error was identified as a dysfunctional maintenance organisation at the Operator.)

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