Challenger Disaster: 30 Years On

Aeronautics isn’t just about the Civil and Military Aircraft that fly all over the world on a daily basis – although this tends to be our main focus, it’s also about any situation where flight is achieved and this can include WIG (Wing in Ground Effect) Aircraft and more importantly for this blog entry – Space.

Space, to paraphrase Star Trek, is one of the ‘final frontier{s}’ of human experience. Only the depths of the oceans have been explored less. It is one of the least hospitable places for human life to attempt to explore. This means those who seek to answer the questions of the wider human race by exploring space – put their lives in great danger, relying on the designs of engineers to keep them safe.

30 years ago today, on the 28th January 1986, one of the most well known of all space related disasters occurred. The NASA Space Shuttle orbiter Challenger broke apart just 73 seconds into its initial lift-off from the Kennedy Space Centre as part of a six day mission STS-51-L. All seven crew members died in the disaster, although the exact timing of their deaths following the initial incident is unclear.

 The Challenger flight 51-l crew" by NASA - Licensed under Public Domain via Commons.

The Challenger flight 51-l crew by NASA – Licensed under Public Domain via Commons.

Subsequent investigations pointed to the disintegration of the launch vehicle beginning after an O-ring seal in the right solid rocket booster (SRB) failed during lift-off – this caused a breach in the joint of the SRB it sealed. From this, pressurised burning gas from within the solid rocket motor could reach the outside and damage the external fuel tank and field joints. Separation occurred, leading to structural failure of the external tank. At this point aerodynamic forces broke up the orbiter. Fragments from the incident descended to the Atlantic Ocean floor where they were recovered after a lengthy search and rescue operation.

Booster Rocket Breach by NASA - Licensed under Public Domain via Commons

Booster Rocket Breach by NASA – Licensed under Public Domain via Commons

Investigations into the disaster followed and the Rogers Commission was established to report to President Reagan on the causes of the disaster on Challenger’s 10th mission. The commission discovered the O-ring failure and following further study, attributed it to a design flaw, as it could be too easily compromised by a range of factors, one of which was low temperatures and cold weather. Further, it determined the ‘contributing causes’ that led to such an accident being possible. That both NASA and the contractor, Morton Thiokol, failed to respond adequately to the design flaw. That the launch decision making process was also seriously flawed and that the risk from the design issues was known but that there were no checks and balances to protect from such a decision being made. The disaster lead to the grounding of the Space Shuttle fleet for a period of around 3 years. During this time, changes had to be implemented; safety measures, SRB redesigns and new policies on decision making were all part of this process.

Although these changes were made by NASA following the incident, it is often argued that the changes in the management structure and culture have not been deep or long lasting – an argument levelled at NASA once again following the 2003 Space Shuttle Columbia disaster. Columbia broke up over Texas and Louisiana on re-entry to Earth’s atmosphere following damage caused by foam insulation breaking off the external tank. Investigations led to the conclusion that NASA had failed to learn lessons from the Challenger disaster and that the same “Flawed decision making process” (Columbia Accident Investigation Board; CAIB) still existed.

So 30 years on, what can we still learn from the Challenger disaster? It is commonly used as a case study in engineering – looking at safety in engineering, ethics, whistle-blowing, communications and group decision-making. The engineer who warned about the effect on the O-rings, Roger Boisjoly, was, prior to his death in 2012, a speaker on workplace ethics and is held as an example of honesty and integrity. As engineers, by studying the disaster and the various complications around the event – we can improve our own understanding of safety, management and ethics within our field.

The 1985 Manchester Air Disaster – 30 Years On

A memorial service is being held later today (22nd August 2015) to mark the 30th Anniversary of the Manchester Air Disaster in which 55 people died, two were crew members and the remaining 53 were passengers on the British Airtours 737 jet.

131 passengers boarded flight 28M for its scheduled flight to Corfu that day. The pilots heard a loud thud as the Boeing 736 traveled along the runway, their first thoughts being a burst tyre. However, an engine failure had sparked a dangerous chain reaction, leading to a punctured fuel tank. Take-off had to be abandoned and the plane brought to a swift halt, but smoke and flames quickly engulfed the rear of the aircraft – causing panic in the cabin.

The Boeing 737 Aircraft where 55 people died - image sourced from bbc.co.uk news reports

The Boeing 737 Aircraft where 55 people died – image sourced from bbc.co.uk news reports

Nearly all of the victims died as a result of the effects of smoke inhalation as they tried to reach the front exits – one of which had jammed. The investigation by the Air Accident Investigation Branch (AAIB) lead to a raft of safety changes.

The AAIB report at the time states the accident cause;

“The cause of the accident was an uncontained failure of the left engine, initiated by a failure of the No. 9 combustor can which had been the subject of a repair. A section of the combustor can, which was ejected forcibly from the engine, struck and fractured an underwing fuel tank access panel.”

One of the first things the investigation found, was that the position of the aircraft, when it finally came to a halt made things far worse – there was a prevailing wind fanning the flames onto the fuselage of the aircraft.

The main recommendations of the report were:

  • In the event of a fire, procedures to be developed to allow/enable the crew to position an aircraft with the fire downwind of the fuselage.
  • Fire extinguishing techniques inside passengers cabins to be reviewed to deal with internal fires.
  • Aircraft cabin materials to be fire resistant, this is to include seat covers/wall/ceiling panels.
  • Onboard water spray/mist fire extinguishing systems to be developed as a priority matter of urgency.
  • A review to examine the existing requirements over “unobstructed access” to exits and whether they need updating in light of this accident.
  • Distribution of experienced cabin crew throughout the cabin.

Many aspects of aviation fire evacuation procedures have changed as a result of this disaster. An aircraft on fire will now always stop upon the runway itself, rather than taxiing away – meaning that passengers are evacuated far more quickly. Far more visible is the removal of a seat on each side next to the over-wing exits to create extra space and minimise potential bottlenecks. The access panels for fuel tanks have also been reinforced.

An overhead shot showing the scale of destruction. Source: Manchester Evening News

An overhead shot showing the scale of destruction. Source: Manchester Evening News

But could such a disaster ever happen again, even with the 30 years of improvements to safety?

Potentially, yes, we can never engineer all the risks out of the system – what we can do however is reduce the likelihood and potential damage from each risk – this reduces the risk and hopefully means that the potential of such an accident happening again is remote.

Sources: AAIB Report 8/1988 Boeing 737-236, G-BGJL, 22 August 1985 Link to Report

MH370 – the mystery – the theories

My earlier article summarised the basic known facts.  Much of this new article is taken from the Royal Aeronautical Society article here http://aerosociety.com/News/Insight-Blog/2007/What-happened-to-flight-MH370 and here is a summary of the main theories of what might have happened:

Theories

1) Depressurisation or toxic fumes – this would explain the change in heading and altitude (to move towards another airfield to land) but not the loss of communications, in either case the pilots could have communicated for a while, and would not have turned the transponder or ACARS off.

2) Hijacking – post 9/11 this is much more difficult than it once was, and the aircraft wasn’t flown to a new destination, or crashed into a building as usual with hijacking, and no sign of concern was shown by the pilots.  If hijacked, why was the ACARS system turned off and why has no group claimed responsibility?

3) Deliberate action by the pilots – no reason for this has ever been identified, if it was a pilot suicide (such as the Germanwings and Egyptair flights) then why did the aircraft carry on flying for another 7 hours?

4) Fire on board – as with the 1998 Swissair MD11 flight https://en.wikipedia.org/wiki/Swissair_Flight_111 a flight deck fire could disable many systems.  The pilots’ initial response would be to turn off electrical systems while they diagnose the problem, which could lead to the radio and ACARS etc being switched off and the lack of communications. They would also turn towards the nearest airport, which could explain the westward turn towards Phuket and Langkawi.  However it would then be strange for the aircraft to carry on flying for another 7 hours if catastrophic damage had been experienced that prevented communications but allowed the aircraft to carry on flying.

5) A combination of two – a fire on board followed by a depressurisation or by  incapacitation of the pilots after they sorted out the source of the fire could lead to the events as known.  This would be unusual but it is equally unusual for a B777 to disappear in such strange circumstances.

Whatever the cause, unless the FDR and CVR or indeed the main wreckage is found, this will remain a real mystery.

Martin Fiddler

MH370 – the mystery – known facts

Details from www.bbc.co.uk

The known facts

On 8 March 2014 a Malaysian Airlines Boeing 777 en route from KL to Beijing disappeared in what are still considered to be unusual and very strange circumstances. It took off at at 00.41 and radio contact was lost after a routine call at 01.19.  A routine ACARS transmission was received at 01.07 but the 01.37 transmission was not received, and at around 01.20 the transponder stopped transmitting secondary information such as altitude and speed. At 01.21 the aircraft failed to check-in with ATC at Ho Chi Minh City. At 02.22 the a final primary radar return was received, the aircraft being off-track to the south of Phuket, having turned towards Lankowi.   Seven Inmarsat satellite pings were received between 02.28 and 08.11, giving a rough location to the NW of the Australian coast.  At take-off the aircraft would have had enough fuel for about eight hours flight, so the final communications fit in well with it running out of fuel.  A search commenced, clearly becoming much more difficult after the 30 or so days that the FDR and CVR sonar pinger battery would have run out.

On 29 July 2015, 16 months later, a piece of MH370’s wing washed up on Reunion Island. It was a flaperon, more commonly known as an inboard or high-speed aileron, and being hollow it had floated. It showed signs of impact damage, as would be expected if the aircraft had hit the sea at high speed.  My next article will discuss the various theories.

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Martin Fiddler