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Accident and Serious Incident Reports: LB

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Article Information
Category: Level Bust Level Bust
Content source: SKYbrary About SKYbrary
Content control: SKYbrary About SKYbrary

Definition

Accident and Serious Incident Reports relating to accidents which involved Level Bust

The events are organised under the following sub-categories:

Accepted ATC Clearance not Followed

  • A321 / B738, en-route, south eastern Bulgaria, 2016 (On 8 September 2016, an Airbus A321 en route in Bulgarian airspace at FL 350 was given and acknowledged a descent but then climbed and came within 1.2nm of a descending Boeing 737. The Investigation found that the inexperienced A321 First Officer had been temporarily alone when the instruction was given and had insufficient understanding of how to control the aircraft. It was also found that despite an STCA activation of the collision risk, the controller, influenced by a Mode ‘S’ downlink of the correctly-set A321 cleared altitude, had then added to the risk by instructing the 737 to descend.)
  • C525 / B773, vicinity London City UK, 2009 (On 27 July 2009, a Cessna 525 departing from London City failed to comply with the initial 3000 feet QNH SID Stop altitude and at 4000 feet QNH in day VMC came into close proximity on an almost reciprocal heading with a Boeing 777-300ER. The 777, on which line training was being conducted, failed to follow any of the three TCAS RAs generated. Actual minimum separation was approximately 0.5nm laterally and estimated at between 100 feet and 200 feet vertically. It was noted that the Cessna had been given a stepped climb SID.)
  • A310 / B736, en-route, Southern Norway, 2001 (On 21 February 2001, a level bust 10 nm north of Oslo Airport by a climbing PIA A310 led to loss of separation with an SAS B736 in which response to a TCAS RA by the A310 not being in accordance with its likely activation (descend). The B736 received and correctly actioned a Climb RA.)
  • B763, en-route North Bay Canada, 2009 (On 19 June 2009 a Boeing 767-300 was level at FL330 in night IMC when the Captain’s altimeter and air speed indicator readings suddenly increased, the latter by 44 knots. The altimeter increase triggered an overspeed warning and the Captain reduced thrust and commenced a climb. The resultant stall warning was followed by a recovery. The Investigation found that a circuitry fault had caused erroneous indications on only the Captain’s instruments and that contrary to the applicable QRH procedure, no comparison with the First Officer’s or Standby instruments had been made. A related Operator FCOM error was also identified.)
  • BE20/SF34, vicinity Stornoway UK, 2011 (On 31 December 2011 a USAF C12 Beech King Air descended 700 feet below the cleared outbound altitude on a procedural non precision approach to Stornoway in uncontrolled airspace in IMC and also failed to fly the procedure correctly. As a result it came into conflict with a Saab 340 inbound on the same procedure. The Investigation found that the C12 crew had interpreted the QNH given by ATC as 990 hPa as 29.90 inches, the subscale setting units used in the USA. The Saab 340 pilot saw the opposite direction traffic on TCAS and descended early to increase separation.)
  • FA50, vicinity London City UK, 2010 (On 21 January 2010, a Mystere Falcon 50 being operated by TAG Aviation on a positioning flight from Biggin Hill to London City in day VMC began a descent at a high rate below its cleared altitude of 2000 ft amsl because the aircraft commander believed, on the basis of external visual cues, that the aircraft was on a final approach track for Runway 27 at destination when in fact it was downwind for Runway 09. After an alert from ATC as the aircraft passed 900 ft agl at a rate of descent of approximately 2200 fpm, recovery to a normal landing on Runway 09 was achieved.)

... further results

SID Bust

  • C525 / B773, vicinity London City UK, 2009 (On 27 July 2009, a Cessna 525 departing from London City failed to comply with the initial 3000 feet QNH SID Stop altitude and at 4000 feet QNH in day VMC came into close proximity on an almost reciprocal heading with a Boeing 777-300ER. The 777, on which line training was being conducted, failed to follow any of the three TCAS RAs generated. Actual minimum separation was approximately 0.5nm laterally and estimated at between 100 feet and 200 feet vertically. It was noted that the Cessna had been given a stepped climb SID.)
  • B773, vicinity Houston TX USA, 2014 (On 3 July 2014, a Boeing 777-300 departing Houston came within 200 feet vertically and 0.61nm laterally of another aircraft after climbing significantly above the Standard Instrument Departure Procedure (SID) stop altitude of 4,000 feet believing clearance was to FL310. The crew responded to ATC avoiding action to descend and then disregarded TCAS 'CLIMB' and subsequently LEVEL OFF RAs which followed. The Investigation found that an inadequate departure brief, inadequate monitoring by the augmented crew and poor communication with ATC had preceded the SID non-compliance and that the crew should have followed the TCAS RAs issued.)

Clearance Readback Error Undetected

  • A319/B733, en-route, near Moutiers France, 2010 (On 8 July 2010 an Easyjet Airbus A319 on which line training was being conducted mis-set a descent level despite correctly reading it back and, after subsequently failing to notice an ATC re-iteration of the same cleared level, continued descent to 1000 feet below it in day VMC and into conflict with crossing traffic at that level, a Boeing 737. The 737 received and actioned a TCAS RA ‘CLIMB’ and the A319, which received only a TCAS TA, was given an emergency turn by ATC. The recorded CPA was 2.2 nm and 125 feet.)
  • C525 / B773, vicinity London City UK, 2009 (On 27 July 2009, a Cessna 525 departing from London City failed to comply with the initial 3000 feet QNH SID Stop altitude and at 4000 feet QNH in day VMC came into close proximity on an almost reciprocal heading with a Boeing 777-300ER. The 777, on which line training was being conducted, failed to follow any of the three TCAS RAs generated. Actual minimum separation was approximately 0.5nm laterally and estimated at between 100 feet and 200 feet vertically. It was noted that the Cessna had been given a stepped climb SID.)
  • E145, en-route, north east of Madrid Spain, 2011 (On 4 August 2011, a Luxair Embraer 145 flying a STAR into Madrid incorrectly read back a descent clearance to altitude 10,000 feet as being to 5,000 feet and the error was not detected by the controller. The aircraft was transferred to the next sector where the controller failed to notice that the incorrect clearance had been repeated. Shortly afterwards, the aircraft received a Hard EGPWS ‘Pull Up’ Warning and responded to it with no injury to the 47 occupants during the manoeuvre. The Investigation noted that an MSAW system was installed in the ACC concerned but was not active.)
  • A320, vicinity Oslo Norway, 2008 (On 19 December 2008, an Aeroflot Airbus A320 descended significantly below its cleared and acknowledged altitude after the crew lost situational awareness at night whilst attempting to establish on the ILS at Oslo from an extreme intercept track after a late runway change and an unchallenged incorrect readback. The Investigation concluded that the response to the EGPWS warning which resulted had been “late and slow” but that the risk of CFIT was “present but not imminent”. The context for the event was considered to have been poor communications between ATC and the aircraft in respect of changes of landing runway.)
  • B738/A319 en-route, south east of Zurich Switzerland, 2013 (On 12 April 2013, a Ryanair Boeing 737-800 took a climb clearance intended for another Ryanair aircraft on the same frequency. The aircraft for which the clearance was intended did not respond and the controller did not notice that the clearance readback had come from a different aircraft. Once the wrong aircraft began to climb, from FL360 to FL380, a TCAS RA to descend occurred due to traffic just transferred to a different frequency and at FL370. That traffic received a TCAS RA to climb. STCA was activated at the ATS Unit controlling both Ryanair aircraft.)

TCAS RA Response

  • DH8A/DH8C, en-route, northern Canada, 2011 (On 7 February 2011 two Air Inuit DHC8s came into head-to-head conflict en route over the eastern shoreline of Hudson Bay in non radar Class ‘A airspace when one of them deviated from its cleared level towards the other which had been assigned the level 1000 feet below. The subsequent investigation found that an inappropriate FD mode had been used to maintain the assigned level of the deviating aircraft and noted deficiencies at the Operator in both TCAS pilot training and aircraft defect reporting as well as a variation in altitude alerting systems fitted to aircraft in the DHC8 fleet.)
  • C525 / B773, vicinity London City UK, 2009 (On 27 July 2009, a Cessna 525 departing from London City failed to comply with the initial 3000 feet QNH SID Stop altitude and at 4000 feet QNH in day VMC came into close proximity on an almost reciprocal heading with a Boeing 777-300ER. The 777, on which line training was being conducted, failed to follow any of the three TCAS RAs generated. Actual minimum separation was approximately 0.5nm laterally and estimated at between 100 feet and 200 feet vertically. It was noted that the Cessna had been given a stepped climb SID.)
  • A319/B733, en-route, near Moutiers France, 2010 (On 8 July 2010 an Easyjet Airbus A319 on which line training was being conducted mis-set a descent level despite correctly reading it back and, after subsequently failing to notice an ATC re-iteration of the same cleared level, continued descent to 1000 feet below it in day VMC and into conflict with crossing traffic at that level, a Boeing 737. The 737 received and actioned a TCAS RA ‘CLIMB’ and the A319, which received only a TCAS TA, was given an emergency turn by ATC. The recorded CPA was 2.2 nm and 125 feet.)
  • B773, vicinity Houston TX USA, 2014 (On 3 July 2014, a Boeing 777-300 departing Houston came within 200 feet vertically and 0.61nm laterally of another aircraft after climbing significantly above the Standard Instrument Departure Procedure (SID) stop altitude of 4,000 feet believing clearance was to FL310. The crew responded to ATC avoiding action to descend and then disregarded TCAS 'CLIMB' and subsequently LEVEL OFF RAs which followed. The Investigation found that an inadequate departure brief, inadequate monitoring by the augmented crew and poor communication with ATC had preceded the SID non-compliance and that the crew should have followed the TCAS RAs issued.)
  • GLF5 / A319, south-eastern France, 2004 (On 16 September 2004, a loss of separation occurred over Geneva between Air France A319 and a Gulfstream 5 which commenced descent without clearance by ATC and with coordinated TCAS RAs not followed by either aircraft.)

Manual Flight

  • DH8A/DH8C, en-route, northern Canada, 2011 (On 7 February 2011 two Air Inuit DHC8s came into head-to-head conflict en route over the eastern shoreline of Hudson Bay in non radar Class ‘A airspace when one of them deviated from its cleared level towards the other which had been assigned the level 1000 feet below. The subsequent investigation found that an inappropriate FD mode had been used to maintain the assigned level of the deviating aircraft and noted deficiencies at the Operator in both TCAS pilot training and aircraft defect reporting as well as a variation in altitude alerting systems fitted to aircraft in the DHC8 fleet.)
  • F15 / E145, en-route, Bedford UK, 2005 (On 27 January 2005, two USAF-operated McDonnell Douglas F15E fighter aircraft, both continued to climb and both passed through the level of an Embraer 145 being operated by British Airways Regional on a scheduled passenger flight from Birmingham to Hannover, one seen at an estimated range of 100 feet.)
  • A319 / B744, en-route near Oroville WA USA, 2008 (On 10 January 2008, an Air Canada Airbus A319 en route over the north western USA encountered unexpected sudden wake vortex turbulence from an in trail Boeing 747-400 nearly 11nm ahead to which the pilots who then responded with potentially hazardous flight control inputs which led to reversion to Alternate Control Law and aggravated the external /disturbance to the aircraft trajectory with roll up to 55° and an unintended descent of 1400 feet which with cabin service in progress and sea belt signs off led to cabin service carts hitting the cabin ceiling and several passenger injuries, some serious.)
  • A332, en-route, near Dar es Salaam Tanzania, 2012 (On 27 February 2012, the crew of an Airbus A330 en route at night and crossing the East African coast at FL360 encountered sudden violent turbulence as they flew into a convective cell not seen on their weather radar and briefly lost control as their aircraft climbed 2000 feet with resultant minor injuries to two occupants. The Investigation concluded that the isolated and rapidly developing cell had not been detected because of crew failure to make proper use of their weather radar, but noted that activation of flight envelope protection and subsequent crew action to recover control had been appropriate.)
  • B788, vicinity Amritsar India, 2018 (On 19 April 2018, a Boeing 787-8 suddenly encountered a short period of severe turbulence as it climbed from FL160 towards clearance limit FL 190 during a weather avoidance manoeuvre which had taken it close to the Amritsar overhead and resulted in a level bust of 600 feet, passenger injuries and minor damage to cabin fittings. The Investigation found that the flight had departed during a period of adverse convective weather after the crew had failed to download a pre flight met briefing or obtain and review available weather updates.)
  • B733, vicinity Helsinki Finland, 2008 (On 26 March 2008, a Ukraine International Airlines’ Boeing 737-300 being vectored by ATC to the ILS at destination Helsinki in IMC descended below its cleared altitude and came close to a telecommunications mast. ATC noticed the deviation and instructed a climb. The investigation attributed the non-compliance with the accepted descent clearance to the failure of the flight crew to operate in accordance with SOPs. It was also noted that the way in which ATC safety systems were installed and configured at the time of the occurrence had precluded earlier ATC awareness of the hazard caused by the altitude deviation.)

... further results

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