HELIOS AIRWAYS FLIGHT 522

Helios Airways Flight 522 was a Helios Airways Boeing 737-300 flight that crashed into a mountain on 14 August 2005 at 12:04 EEST, north of Marathon and Varnavas, Greece. Rescue teams located wreckage near the community of Grammatiko40 km (25 miles) from Athens. All 121 on board were killed.

Background

The aircraft involved in this incident was first flown on 29 December 1997 and had been operated by DBA until it was leased by Helios Airways on 16 April 2004 and nicknamed Olympia, with registration 5B-DBY. Aside from the downed aircraft, the Helios fleet consisted of two leased Boeing 737-800s and an Airbus A319-111 delivered on 14 May 2005

Flight and crash

Hans-Jürgen Merten, who was a German contract pilot hired by Helios for the holiday flights, served as the captain. Pampos Charalambous, a Cypriot who flew for Helios, served as the first officer. 32-year old Louisa Vouteri, a Greek national living in Cyprus who served as a chief purser, replaced a sick colleague.

The flight, which left Larnaca, Cyprus at 09:07 local time, was en route to Athens, and was scheduled to continue to Prague. Before take-off the crew failed to set the pressurisation system to "Auto," which is contrary to standard Boeing procedures. Minutes after take-off the cabin altitude horn activated as a result of pressurization. It was, however, misidentified by the crew as a take-off configuration warning, which signals that the aircraft is not ready for take-off, and can only sound on the ground. The horn can be silenced by the crew with a switch on the overhead panel.

Above 14,000 ft (4,267 m) cabin altitude, the oxygen masks in the cabin automatically deployed. An Oxy ON warning light on the overhead panel in the cabin illuminates when this happens. At this point, the crew contacted the ground engineers. Minutes later a master caution warning light activated, indicating an abnormal situation in a system. This was misinterpreted by the crew as indicating that systems were overheating.

At some point later the captain radioed the engineer on the ground to say that the ventilation fan lights were off. This suggests that the captain was suffering from hypoxia, as the 737-300 has no such lights. The engineer asked the captain to repeat. The captain then said that the equipment cooling lights were off, which again suggested confusion. The engineer said, "This is normal, please confirm the problem." The engineer then asked, "Can you confirm that the pressurization system is set to AUTO?" The captain, however, disregarded the question and instead asked in reply, "Where are my equipment cooling circuit breakers?" The engineer then asked whether the crew could see the circuit breakers, but received no response.

After the flight failed to contact air traffic control upon entering Greek air space, two F-16 fighter aircraft from the Hellenic Air Force 111th Combat Wing were scrambled from Nea Anchialos Air Base to establish visual contact. They noted that the aircraft appeared to be on autopilot. In accordance with the rules for handling "renegade" aircraft incidents (where the aircraft is not under pilot control), one fighter approached to within 300 ft (91 m), and saw the first officer was slumped motionless at the controls. The pilot could also see that the captain was not upright in the cockpit and that oxygen masks were seen dangling in the passenger cabin.

Later, the F-16 pilots saw the flight attendant Andreas Prodromou enter the cockpit and sit at the controls, seemingly trying to regain control of the aircraft. He eventually noticed the F-16, and signalled him. The pilot pointed forward as if to ask, "Can you carry on flying?" Prodromou responded by shaking his head and pointing downward. The cockpit voice recorder recorded him calling "mayday" multiple times. Within minutes, due to lack of fuel, the engines failed in quick succession and the aircraft began to descend. Prodromou grabbed the yoke and attempted to steer, but the plane continued, hit the ground and exploded. At the time of impact, the passengers and crew were likely unconscious but breathing. None survived.

The aircraft was carrying 115 passengers and a crew of 6. The passengers included 67 due to disembark at Athens, with the remainder continuing to Prague. The bodies of 118 individuals were recovered. The passenger list included 93 adults and 22 people under the age of 18. Cypriot nationals comprised 103 of the passengers and Greek nationals comprised the remaining 12.

The cause of the crash (according to air crash investigations) was that the cabin pressurization control valve was set to manual and was not switched back to auto after post-maintenance pressurisation testing was completed. As a result, the cabin never pressurised during the ascent to 35,000 feet (11,000 m). The flight attendant seen in the cockpit managed to stay conscious by using the spare oxygen bottles provided in the passenger cabin for crew use.

Investigation

Loss of cabin pressure—which, without prompt alleviation, would cause pilot unconsciousness—is the leading theory explaining the accident. This would account for the release of oxygen masks in the passenger cabin. Weighing against this is the fact that the pilots should have been able to don their own fast-acting masks and make an emergency descent to a safe altitude provided that they recognized the pressurization system as the source of the alarm and acted before their minds were too impaired by hypoxia.

The flight data recorder and cockpit voice recorder were sent to Paris for analysis. Authorities served a search warrant on Helios Airways' headquarters in Larnaca, Cyprus, and seized "documents or any other evidence which might be useful in the investigation of the possibility of criminal offences."

Most of the bodies recovered were burned beyond visual identification by the fierce fires that raged for hours in the dry brush and grass covering the crash site. However, it was determined that a body found in the cockpit area was that of a male flight attendant and DNA testing revealed that the blood on the aircraft controls was that of flight attendant Andreas Prodromou, a pilot-in-training with approximately 260–270 hours of training completed. Autopsies on the crash victims showed that all were alive at the time of impact, but it could not be determined whether they were conscious as well.

The preliminary investigation reports state that the maintenance performed on the aircraft had left the pressurization control on a 'manual' setting, in which the aircraft would not pressurise automatically on ascending; the pre-takeoff check had not disclosed nor corrected this. As the aircraft passed 10,000 feet (3,000 m), the cabin altitude alert horn sounded. The horn also sounds if the aircraft is not properly set for takeoff, e.g. flaps not set, and thus it was assumed to be a false warning. The aircrew found a lack of a common language and inadequate English a hindrance in solving the problem. The aircrew called maintenance to ask how to disable the horn, and were told where to find the circuit-breaker. The pilot left his seat to see to the circuit breaker and both aircrew lost consciousness shortly afterwards.

The leading explanation for the accident is that the cabin pressurisation did not operate and this condition was not recognised by the crew before they became incapacitated. Decompression would have been fairly gradual as the aircraft climbed under the control of the flight management system. The pressurisation failure warning on this model should operate when the effective altitude of the cabin air reaches 10,000 ft (3,000 m) at which altitude a fit person will have full mental capacity.

The emergency oxygen supply in the passenger cabin of this model of Boeing 737 is provided by chemical generators that provide enough oxygen, through breathing masks, to sustain consciousness for about 12 minutes, normally sufficient for an emergency descent to 10,000 feet (3,000 m), where atmospheric pressure is sufficient to sustain life without supplemental oxygen. Cabin crew have access to portable oxygen sets with considerably longer duration. Emergency oxygen for the flight crew comes from a dedicated tank.

Timeline

Path of Helios Airways Flight 522
Date: 14 August 2005 All times EEST (UTC + 3h), PM in bold
Time	Event
0900	Scheduled departure
0907	Departs Larnaca International Airport
0911	Pilots report air conditioning problem
0912	Cabin Altitude Warning sounds at 12,040 feet (3,670 m)
0920	Last contact with Nicosia ATC; Altitude is 28,900 feet (8,809 m)
0923	Now at 34,000 feet (10,400 m); Probably on autopilot
0937	Enters Athens Flight Information Region
1007	No response to radio calls from Athens ATC.
1020	Athens ATC calls Larnaca ATC; Gets report of air conditioning problem
1024	Hellenic Air Force (HAF) alerted to possible renegade aircraft
1045	Scheduled arrival in Athens
1047	HAF reassured that the problem seemed to have been solved
1055	HAF ordered to intercept by Chief of General Staff, Admiral Panagiotis Chinofotis
1105	Two F-16 fighters depart Nea Anchialos
1124	Located by F-16s over Aegean island of Kea
1132	Fighters see co-pilot slumped over, cabin oxygen deployed, no signs of terrorism
1149	Fighters see an individual in the cockpit, apparently trying to regain control of aircraft
1150	Left (#1) engine stops operating, presumably due to fuel starvation
1154	CVR records two MAYDAY messages
1200	Right (#2) engine stops operating
1204	Aircraft crashes in mountains near Grammatikos, Greece

BA 777-200: TAXIING ERROR PRIOR TO TAKE-OFF

Two passengers attempted to stop a British Airways Boeing 777-200 from taking off from a Caribbean airport last September, after realising the crew had lined up at the wrong runway intersection, but were too late to prevent the departure.

The pilots of the twin-jet, bound for Antigua, had intended to depart from the south-western end of runway 07 - the 'A' intersection - at St Kitts' Bradshaw International Airport.

Despite specifically requesting a departure from 'A', the aircraft mistakenly taxied instead for the 'B' intersection, near the runway's midpoint, leaving available take-off distance of just 1,220m (4,000ft). The take-off performance calculations had been based on a distance of 1,915m.

The oversight escaped detection despite several references and queries in the communications between the crew and air traffic control.

The UK Air Accidents Investigation Branch reveals that the carrier's station engineer and airport duty manager were on board the 777 and realised the error as the aircraft lined up on the runway.

The engineer quickly moved from his seat to speak to a member of the cabin crew, telling her that he needed to contact the pilots immediately to warn them the aircraft was wrongly positioned.

In the cockpit the captain had specifically commented that the runway looked short. Neither pilot had been to the airport before and the lack of a tractor meant the crew had taxied the jet from the stand themselves. But, in spite of the captain's concerns, neither cross-checked the jet's location on the runway. Instead the captain told the co-pilot to "stand on the brakes", says the AAIB, and apply a high thrust setting - some 55% of N1 level - before releasing the brakes for the take-off roll.

In the cabin behind, the station engineer realised that the aircraft was powering up for take-off and abandoned his bid to reach the crew. The 777 accelerated but reached the touchdown-zone markers for the reverse-direction runway 25 by the time it passed the crucial V1 decision speed, and lifted off about 300m from the end of the paved surface.

Taking off from the 'B' intersection reduces the available distance by 1,110m and the AAIB says that British Airways does not authorise 777 departures from this point on runway 07.

The incident, on 26 September last year, occurred in daylight although the sun was low in the west.

While the AAIB attributes the event to simple lack of familiarity with the airport, combined with disorientation from poor signage, it also underlines the psychological factors which contributed to the failure to identify the error.

Bradshaw is a simple airport, and the crew did not conduct a taxi briefing. The AAIB says that the crew would probably have briefed the route at a larger, more complex airport.

It adds that the crew appears to have suffered from "confirmation bias", noticing only the evidence that backed their mistaken assumption of being at the correct intersection.

Crew resource management training should address this tendency in two ways, says the AAIB: by emphasising the need to "seek evidence that disproves assumptions whenever they are called into doubt" and by providing communications skills needed for "confident and clear discussion" of the problem.

QANTAS A330-301: ADIRU FAILURE

Qantas Flight 72 (QF72) was a scheduled flight from Singapore Changi Airport to Perth Airport on 7 October 2008 that made an emergency landing at Learmonth airport near the town of Exmouth, Western Australia following an in-flight accident featuring a pair of sudden un-commanded pitch-down manoeuvres that resulted in serious injuries to many of the occupants. The injuries included fractures, lacerations and spinal injuries.

Aircraft Details

VH-QPA was delivered new to Qantas on 26 November 2003, initially as A330-301. It later had a change in engine type fitted and was re-designated as an Airbus A330-303 in November 2004.

Flight Details

The accident began at 12:40:28 WST. The aircraft was travelling at around 37,000 feet (11,000 m) when pilots received an electronic message warning them of an irregularity with autopilot and inertial reference systems. The autopilot disengaged automatically, and the aircraft climbed 200 feet (60 m) under manual control. The autopilot was re-engaged when the aircraft returned to the prior selected flight level before the autopilot was disengaged for the remainder of the flight. At 12:42:27 the aircraft made a sudden un-commanded pitch down manoeuvre, recording -0.8 g, reaching 8.4 degrees pitch down and rapidly descending 650 feet (200 m) in about 20 seconds before the pilots were able to return the aircraft to the assigned cruise flight level. At 12:45:08 the aircraft then made a second un-commanded manoeuvre of similar nature, this time reaching +0.2 g, 3.5 degrees pitch down and descending 400 feet (120 m) in about 16 seconds before being returned to level flight. Unrestrained passengers and crew as well as some restrained passengers on board were flung around the cabin or crashed on overhead luggage compartments. The pilots stabilised the plane and declared a state of alert (a PAN-PAN is broadcast), which was later updated to a MAYDAY when the extent of injuries was relayed to the flight crew. Forty minutes later, the plane made an emergency landing at Learmonth airport.

Investigation

The ATSB investigation was supported by the Australian Civil Aviation Safety Authority (CASA), Qantas, BEA (France) and Airbus. Copies of data from the aircraft's flight data recorder and cockpit voice recorder were sent to the BEA and Airbus.

The aircraft was equipped with a Northrop Grumman made ADIRS, which investigators sent to the manufacturer in the US for further testing. On 15 January 2009 the EASA issued an Emergency Airworthiness Directive to address the above A330 and A340 Northrop-Grumman ADIRU problem of incorrectly responding to a defective inertial reference.

The Australian Transport Safety Bureau (ATSB) identified in a preliminary report that a fault occurred within the Number 1 Air Data Inertial Reference Unit (ADIRU) and is the "likely origin of the event". The ADIRU (one of three such devices on the aircraft) began to supply incorrect data to the other aircraft systems.

The initial effects of the fault were:

  §  False stall and overspeed warnings

  §      Loss of attitude information on the Captain's primary flight display

  §      Several Electronic Centralised Aircraft Monitor (ECAM) system warnings

About two minutes later, ADIRU #1, which was providing data to the captain's primary flight display, provided very high (and false) indications for the aircraft's angle of attack, leading to

  §       The flight control computers commanding a nose-down aircraft movement, which resulted in  the aircraft pitching down to a maximum of about 8.5 degrees,

  §       The triggering of a Flight Control Primary Computer pitch fault.

Airbus released an Operators Information Telex to operators of Airbus A330and A340 aircraft with procedural recommendations and checklists to minimise risk in the event of a similar incident.