My last posting addressed accident flight recorders and airworthiness requirements. That’s not enough. It’s important to note that aircraft equipage standards are addressed in operational rules. So, the airworthiness requirements define what an acceptable installation looks like but as to whether an operator needs to have specific equipage or not, that’s down to the operational rules in each country.
Internationally, the standards and recommended practices of ICAO Annex 6 are applicable. These cover the operation of aircraft. Flight recorders are addressed in para 6.3.1. and Appendix 8. Let’s note that ICAO is not a regulator. There are international standards but operational rules in each country apply to each country’s aircraft.
One of the major advances in accident flight recorders technology is the capability to record more data than was formerly practical. This has led to standards for Cockpit Voice Recorders (CVRs) advancing from 2-hour recording duration to 25-hours.
Proposed rule changes have been hampered by the impact of the global pandemic. Some new operational rules apply only to newly built aircraft. That means some existing aircraft can retain their 2-hour CVRs.
Another technology advance is what’s known as Recorder Independent Power Supply (RIPS). RIPS can provided power to the CVR for at least 10 minutes after aircraft electrical power is lost. The RIPS is often offered as a relatively straightforward aircraft modification.
I do not know if the South Korea Boeing 737-800 was required to have accident recorders with the capabilities listed above. If they were not, then there’s a good basis for recommending that changes be made to existing aircraft.
There’s quite a bit of chatter on social media about accident flight recorders.
One of the skills required by an aircraft accident investigator, and not often mentioned, is the ability to grapple with rules, regulations, and technical requirements. This is given that civil aviation is one of the most highly regulated industries in the world.
The story of the development of the accident flight recorder is a long one. No way can a few words here do justice to all the efforts that has been made over decades to ensure that this vital tool for accident and incident investigation does what it’s intended to do.
In fact, that’s the first technical requirement to mention for accident recorders. Namely, FAR and CS Subpart F, 25.1301: Each item of installed equipment must be of a kind and design appropriate to its intended function. That basic intended function being to preserve a record of aircraft operational data post-accident.
Aircraft accident recorders are unusual. They are mentioned in the airworthiness requirements, however they play no part in the day-to-day airworthiness of an aircraft. The reality is more nuanced than that, but an aircraft can fly safely without working flight recorders.
FAR and CS 25.1457 refers to Cockpit Voice Recorders (CVR)[1] and 25.1459 refers to Flight Data Recorders[2]. Both CVR and FDR receive electrical power from the aircraft electrical bus that provides the maximum reliability for operation of the recorder without jeopardising service to essential or emergency electrical loads. Both CVR and FDR should remain powered for as long as possible without jeopardising aircraft emergency operations.
Before drawing too many conclusions, it’s important to look at the above certification requirements in relation to their amendment state at the time of type certification of an aircraft.
If the aircraft of interest is the Boeing 737-800 then the FAA Type Certification date is 13 March 1998 and the EASA / JAA Type Certification date is 9 April 1998. Without wading through all the detailed condition, the certification basis for the above aircraft type was FAR Part 25 Amendment 25-77 and JAR 25 Change 13 [Note: EASA did not exist at the time].
FAR and CS 25.1457 and 25.1459 were in an earlier state than that which is written above. That said, the objective of powering the recorders in a reliable way was still applicable. There was no requirement for the CVR or FDR to be powered by a battery. What hasn’t changed is the requirement for a means to stop a recorder and prevent erasure, within 10 minutes after a crash impact. That’s assuming that aircraft electrical power was still provided.
So, when it’s reported that the South Korea Boeing 737 accident recorders[3] are missing the final 4 minutes of recoding, the cause is likely to be the loss of the aircraft electrical buses or termination by automatic means or the removal of power via circuit breakers. We will need to wait to hear what is found as the on-going accident investigation progresses.
Jeju Air Flight 7C2216, arriving from the Thai capital of Bangkok, at South Korea’s Muan Airport (MWX), crashed at around 9am local time (00:00 GMT/UTC) on Sunday, 29 December 2024.
My condolences to the families and loved ones of those who died or were injured in this fatal aircraft accident.
Pictures of the Jeju Air Boeing 737-800 landing[1] show that no landing gear can be seen deployed. A video image shows the aircraft skidding down the runway at high speed. The aircraft is wings level. It is reported the aircraft overrunning the runway and colliding with a wall or ramp. The video image does suggest that the aircraft engine thrust reversers were deployed. This is wrong. Weight on wheels is needed for deployment.
MWX runway 19 has a Landing Distance Available (LDA) of 2800 m. The local visibility was reported as 9000m and the wind speed at 2kt.
Was the pilot in command trying to go around? The accident flight recordings should answer this question. That is from the aircraft Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR).
This remains a hope. Reports are that the FDR has been damaged. This should not be a surprise given the nature of the impact it suffered. However, both FDR and CVR are designed and tested to survive extreme cases.
The South Korean Ministry of Land, Infrastructure and Transport says that the accident flight and voice recorders have been recovered[2].
Jeju Air is a popular South Korean low-cost airline. The airline was established in 2005.
A full independent accident investigation will no doubt take place. That is in accordance with the standards and recommended practices of ICAO Annex 13.
Current media speculation surrounding possible causes of this Boeing 737 accident do not offer any satisfactory explanation for the sequence of events. For example, it would be astonishing if the root cause of the accident was a bird strike or multiple bird strike shortly before landing. The aircraft has several means to deploy its main undercarriage.
It is likely that safety culture, controller and pilot training, and airport facilities are bigger factors in this fatal accident than the fact that it involved the loss of a Boeing 737-800 aircraft.
NOTE: Boeing 737 “If the gear fails to extend properly or hydraulic system A is lost, the gear can be manually extended by pulling the manual gear extension handles, located in the flight deck.” Landing Gear
POST: The impact test in the applicable technical standards EUROCAE ED55 (FDR) and ED56A (CVR) are demanding. The recorder’s crash protected memory module is fired out of a canon into a shaped target to simulate an accident scenario. It must be readable afterwards.
Finding aircraft wreckage in the deep ocean is possible. However, it requires a degree of good fortune. Most of all, it requires the searcher to look in the right places. Lots of other factors come into play, particularly if the ocean floor is uneven or mountainous.
The primary tool for imaging the ocean floor is SONAR. That’s using the propagation of sound in water. SONAR can be of two types. One is called “passive” and the other called “active”.
The first case is like using a microphone to listen to what’s going on around. Of course, the device used is named appropriately: a hydrophone. It’s a device tuned to work in water and not air. Afterall, sound travels much faster in a liquid than it does in air.
Passive SONAR depends on the object of interest making a noise. Just like we have directional microphones so we can have directional hydrophones.
Passive SONAR is only useful if the aircraft wreckage is making a noise. Since in the case of Flight MH370, the battery powered underwater location beacons attached to the accident flight recorders have long since stopped working this kind of SONAR isn’t going to be much use.
Active SONAR is analogous to RADAR. That is where a pulse of high frequency sound is sent out through a body of water. Then sensitive hydrophones pick up a reflection of that pulse. It is detected and all sorts of miraculous digital signal processing is done with the acoustic signal, and an image is then formed. From that displayed image the human eye or sophisticated algorithms can make sense of what they are looking at on the sea floor.
Active SONAR can give both range and bearing (direction). Timing the sound pluses from their transmission to reception can give a way of calculating range. Or distance from the object providing a reflection. Bats know how to do this as they navigate the dark.
In sea water, there are complications. Sound does not always travel in a straight line in sea water. The speed of sound in water depends on salinity, temperature and pressure. All three of these factors can be measured and compensated for in the SONAR signal processing that I mentioned above. Helpfully at ocean depths beyond a kilometre the calculations become easier.
The average depth of the Indian Ocean is over 3 kilometres. It’s mountainous underwater too. So, what are the chances of finding flight MH370 on the ocean floor after 10-years[1]? This prospect goes back to my earlier comment. It requires the searcher to look in the right places.
Just imagine encountering the Grand Canyon for the first time. It’s nighttime. An important object is lost in the canyon. You only have the vaguest theories as to where the object has come to rest. With a handheld touch you go out to search. What are the chances of finding the object?
There are several factors that are in your favour. One, you know what the object might look like or, at least, in part. Two, the easy search locations (flat/smooth) may be covered relatively quickly. Three, certain areas of the rocky canyon have already been searched. Still the odds are against finding the lost object without a high degree of good fortune.
I wish the new planned searchers much good future[2].
NOTE 1: one of my student apprentice projects was to design and build a Sing-Around Velocimeter for use in relatively shallow sea water[3]. It worked but was cumbersome in comparison with the simple throw away devices used for temperature depth profiling.
NOTE 2: To get down to the ocean depths required it’s a side-scan sonar that may be used. This active sonar system consists of a towed transducer array that can be set to work at different depths. Imaging objects on the seafloor and underwater terrain is done as a towed array moves slowly forward through the water. The scanning part is the acoustic beam sweeps left and right. Each scan builds up part of an image.
In operation, as the frequency of the sound in water goes up so does the resolution of a potential image but, at the same time, the range of the sonar system goes down. Thus, a sonar system used for surveying may have low and high frequency settings. Unlike sound in air, here high frequency means above 500kHz.
NOTE 3: What will an aircraft accident recorder look like after a decade in the deep ocean? It might have survived well given the nature of the dark cold pressured environment. This picture is of an accident recorder recovered from relatively shallow sea water (Swiss Air Flight 111).
The unthinkable happened in 2014. One major international airline suffered two catastrophic accidents. These tragic events ran contrary to all the trends in historic aircraft accident data.
In March, flight MH370 disappeared. In July, flight MH17 was shot down. In both cases there were no survivors from these international flights. This remains an unprecedented situation. It is a sobering consideration that such dreadful events were possible in a mature international framework of civil aircraft operations and regulation.
A decade on the pain of those who lost friends, family and colleagues in these tragedies is not diminished. Aviation should not lessen its attention to discovering more about what happened and putting measure in place to prevent reoccurrence of these events.
These two aviation catastrophes are different in respect of causal factors. One remains a mystery but, from what is known, has the hallmarks of an operational accident. The other is undoubtably an aggressive malicious act. Failings in the two elements of aviation safety and security, often viewed separately, are both capable of catastrophic outcomes.
Malaysia Airlines was a State-owned airline in the traditional model. There’s no reason to suppose that the airline harboured deficiencies that led directly to the two fatal accidents. In hindsight, the question is often asked: could both accidents have been avoided?
The extensive underwater search for MH370, in the southern Indian Ocean, resulted in no findings. However, floating debris from the fateful Boeing 777-200ER was discovered. Unlike what happened with Air France Flight 447 were the installed accident flight recorders were recovered from the deep ocean, there has been no such good fortune in respect of MH370.
Accident flight recorders are one of the primary tools for accident investigators. Installed recorders are built and tested to withstand extreme conditions. The reasonable assumption being that they will be found with any aircraft wreckage. The accident of MH370, is one where a deployable recorder may have been beneficial. That is one that ejects from an aircraft when it is subject to the high impact of the sea surface and then floats, possibly away from an accident site. There is a good case to be made for installing both deployable and installed recorders[1]. Particularly a case for long-range international overwater aircraft operations.
The facts surrounding the criminal act of shooting down of flight MH17 are well established. Sadly, in a troubled world it is impossible to say that such malicious acts will never occur again. What is to be done? Avoidance is by far the optimal approach. Commercial flying over warzones, where heavy weapons are known to be used, is extremely foolish. Now, it is good that much more flight planning attention is paid to understanding where conflict zones exist[2].
NOTE 1: On 07 March 2014 at 1642 UTC1 [0042 MYT, 08 March 2014], a Malaysia Airlines (MAS) Flight MH370, a Beijing-bound international scheduled passenger flight, departed from KL International Airport [KLIA] with a total of 239 persons on board (227 passengers and 12 crew). The aircraft was a Boeing 777-200ER, registered as 9M-MRO.
NOTE 2: On 17 July 2014, at 13:20 (15:20 CET) a Boeing 777-200 with the Malaysia Airlines nationality and registration mark 9M-MRD disappeared to the west of the TAMAK air navigation waypoint in Ukraine. All 298 persons on-bard lost their lives.
Cards on the table. I’m a believer. Despite the immense technical challenges, Hydrogen is a viable fuel for future large civil aircraft. That said, operational service of such revolutionary aircraft isn’t going to happen in a hurry.
Reading the history, Concorde was an incredible test of the boundaries of what was possible and that was met, but it didn’t come easy. Breaking new ground is never easy. [A common saying that’s maybe open to challenge]. In aviation making step-changes happens every decade. What’s nearly always required is exceptional determination, almost beyond reason, large sums of money and special people.
Control systems – no big deal. Mechanical components – evolution possible. Turning a gaseous fuel into high-levels of propulsive thrust – can be done. Building a one-off technology proving research vehicle. It’s happening. At least for the light and commuter class of aircraft.
None of this is enough. Because the gap between an aircraft that can fly and an aircraft that can be produced in the thousands and go on to make an operational living and build an impressive safety and reliability reputation, that’s still a million miles off.
Today, there’s artist impressions of all sorts of different H2 aircraft configurations. It’s like people painted pictures of Mars with imaginary canals, long before anyone knew what the planet looked like in reality. Innovation starts with ideas and not all of them are sound.
As I expressed in my last article, crashworthiness must be given much consideration when speculating about future designs. It’s not always explicit in aircraft certification, cabin safety being the exception, but studying the history of accidents and incidents is essential. One of the successes of the authorities and industry working together is to take lessons learned seriously.
I remember looking at the pictures of the wreckage of Air France Flight 358, which crashed on landing in Toronto, Canada[1]. The fact that there were no fatalities from that accident is a testament to good operations and good design practices. The Airbus aircraft burned out but there was enough time for passengers and crew to get away.
My thought is what kind of H2 aircraft configurations would permit the same opportunity?
Considering this large aircraft accident, and others like it, then there’s a message as to where fuel tanks might best be placed. There’re some aircraft configurations that would have little hope of providing the opportunity for rapid evacuation of hundreds of people.
So, in my mind, don’t attached large pressurised cryogenic fuel tanks to the underbody structure of an aircraft fuselage. However robust the design and build of such fuel tanks they would be unlikely to survive as well as the cabin passenger seats, namely 9g[2]. That would not provide a good outcome post-accident.
Maybe, like aircraft engines sitting on pylons off the wings, that too is a good place for fuel tanks.
This week has been a Hydrogen week. It’s great to learn more of the projects that are out there and the ambitions of those developing systems. Hydrogen is a live subject. Looking at the possible pathways for civil aviation to take there’s a myriad of choices. However, when it comes to the fuel for propulsion there are not so many potentials.
It’s surely the case that at some time in the future the use of fossil fuels to propel us across the skies will no longer be acceptable. Even if I’m talking to climate change sceptics the point must be made that fossil fuels are a limited resource. Not only that but the air quality around airports is a matter of concern.
It’s there in our basic education. Water is H2O. It’s that combination of Hydrogen and Oxygen that is essential to life on Earth. So, if we have a process that provides aircraft propulsion by using Hydrogen it should be a whole lot better for the environment than using Jet A1.
The problem is, and there’s always a problem, to carry enough Hydrogen it will need to be pressurised and in liquid form. That means extremely low temperatures, robust storage containers and extensive leak free plumbing.
Today, we have cars on the road that run on liquefied petroleum gas (LPG). It’s a novelty. It’s less harmful to the environment and can cost less. However, LPG systems need regular servicing. The point of mentioning this pressured gas in a transport system is that it has been integrated into regular everyday usage. That’s knowing that escape of even small quantities of the liquefied gas can give rise to large volumes of gas / air mixture and thus a considerable hazard[1].
Any analogy between the car and the aircraft can be forgotten. That said, one or two of the issues are similar. Yes, what happens when an escaped volume of gas / air mixture is ignited?
What scenarios would bring about conditions whereby a destructive explosion is possible?
Let’s start with the situations where aircraft accidents most often occur. Take-off and landing are those phases of flight. A surprising number of accident scenarios are survivable. The important part being to get an aircraft in trouble on the ground in such a way that an evacuation is possible. That can mean hitting the ground with a great deal of force[2].
Here’s the matter of concern. An aircraft with large cryogenic tanks and associated complex plumbing hits the ground at a force of many “g”. What then happens? Certainly, pressurised liquefied gas would escape. Being a very light gas, the uncontained Hydrogen would rise rapidly. However, trapped amounts of gas / air mixture would remain a hazard. Would that be ignited?
There are a lot of unknowns in my questions. Although there are unknowns, any post impact situation is likely to be very different from a situation with a conventionally fuelled aircraft.
Today’s, burn through requirements ensure that an external fuel fire is held back. Thereby ensuring enough time to evacuate. For a hydrogen aircraft ventilation may be essential to stop build-up of a gas / air mixture inside a fuselage. That means a whole different approach.
Ever since Brexit, I’ve had to have my passport stamped in and out of European countries. It’s like a reversion to the days when I got my first British passport. That was back in the late 70s. It has a frighteningly youthful picture. Occupation – student.
I’m not so phased by the coming changes to European Union (EU) border controls. Naturally, it’s worth asking if Britian has become a more dangerous nation since the time before Brexit when we enjoyed freedom of movement. It’s a pity we didn’t value that freedom a lot more. It was thrown away far too easily.
Today, the electronic border controls expect us to stare at a camera. A securely held, I hope, database is used to check a list of biometric numbers against my image. I guess that’s a sure-fire way of saying that Mr Blogs is indeed someone who looks very much like Mr Blogs. Facial recognition technology has come a long way.
The next steps in tightening-up controls will be fingerprinting[1]. Not in the manner of Sherlock Holmes, with an ink pad. No, in the digital age an ominous machine will scan our fingers and check its records to see that not only does Mr Blogs look as he should but that he’s got the essential characteristics of Mr Blogs.
Certainly, in this new regime British citizens will not be able to overstay in European countries. Ones travel records will be a lot more quantifiable and precise than stamping a piece of paper. That is assuming such digital border control machines will be relatively error free.
One of the benefits of Brexit is that it will be easier to track the movements of British criminals in and out of the EU. The reciprocal will not be true. It will not be easier for British authorities to track continental European criminals in an out of the UK.
Ah the luxury of being a Third Country. Longer ques. More uncertainty. Less privileges.
What’s more is the introduction of the new EU border control systems will be “phased[2]”. This change will not be one big bang. So, different ports and airports will be doing different things at different times. Now, it doesn’t take a genius to see that confusion is most likely.
Travelling in 2025 is going to be more than the usual adventure.
Given the tragic nature of VoePass Linhas Aéreas flight PTB2283, it is a fatal aircraft accident investigation of global importance. The Brazilian Aeronautical Accidents Investigation and Prevention Center (CENIPA) is investigating. CENIPA investigations are based on the international standard, namely ICAO Annex 13.
Both the Cockpit Voice Recorder (CVR) and the Flight Data Recorder (FDR) of the civil aircraft, registered PS-VPB, have been successfully replayed[1]. This is a task that required great care and diligence. The replay data now available to the investigators for detailed analysis, is of the utmost significance.
From the pictures available the external impact damage to the flight recorders is evident. What is important is that the crash protected memory module works as intended. This is solid-state digital memory that is packaged in a way that protects it from extreme conditions.
Finding from this accident investigation could have implications for the whole ATR aircraft fleet worldwide. It’s certain the authorities in Brazil will notify the aviation community if findings indicate corrective action that needs to be immediately taken.
Reports in the public domain indicate that the ATR aircraft had an ice detection system and that alerts could be heard in the cockpit during the flight[2]. Additionally, there is the indication that the crew acted in relation to those cockpit alerts.
[My apologies for a post where I suggested that there may not have been an ice detection sensor and alert on this class of turboprop aircraft. I was in error.].
This chain of events may suggest a simple set of explanations for the loss of control of the aircraft as it approached its destination. However, these matters are never simple, as most catastrophic aviation accidents are a combination of factors.
Even though the crew noted that there was icing, there is, as yet, no indication that the atmospheric conditions experienced by the aircraft in-flight were of a truly exceptional nature. The ATR aircraft is certified for specific icing conditions. There is training and procedures for the encounter of icing conditions.
It is pure speculation on my part, but I am reminded of an aviation accident of more than 40-years ago[3]. The conditions of the accident are different, but a factor may link the two. The last line of the NTSB report abstract says: “and the limited experience of the flight crew in jet transport winter conditions.” A small amount of ice contamination in the wrong place at the wrong time can have much more impact that might be immediately assumed.
We talk of optimism and pessimism as if one presides while the other sleeps. It’s not quite like that in consideration of the legacy around us. There’s no doubt that the 1920s and 1930s were years of austerity and depression. The Great War had an overwhelming impact on all sections of society. The buildings that remain from that era, including the house that I once lived in, do record a simpler style. Material chosen for their functional value rather than decorative.
Victorian’s built with flair and every mechanical contrivance that their technology could provide. Value in longevity was integral in their thinking. Who could imagine the sun setting on British empire?
The brief inter-war period was one of concrete and steel. A bit of classicism retained an influence. Form, fit and function played a bigger part. Modernism meant reflecting the advances in technology that were making great pace. Construction was fast.
Aviation was one of the most notable advances. Post-war flying moved from the military to sport, the recreation of the rich and the wonder of the onlooking public. It went together with the race for speed on land. Everything had to be faster and go further.
Maybe it was the Bauhaus in Germany, that set down some much-copied rules. Symmetry and square lines were on the drawing boards of a lot of public architects. It’s the case that some ornamentation was thrown in where the patrons were wealthy. Even that was relatively muted.
What lasted is no abomination of a poverty of ambition. It’s not utopian. It’s not brutalist. There’s instead a simplicity that was authoritative enough but not too ostentatious.
Pictured above is the 1932 Aero Clubhouse at Brooklands[1] in Surrey. It was designed by Graham Dawbarn[2] in what was a typical 1930s style. It set a trend for aerodrome buildings. Buildings like this one added grandeur to aerodromes where sheet metal hangers and small wooden huts were more often to be seen.
I like these enduring, straightforward, practical buildings. Yes, they are a form of British colonial architecture. One that could be easily reproduced anywhere on the globe. In today’s terms not the least bit environmentally friendly or efficient. Nevertheless, there’s an appeal that marks them out particularly when compared to the sheets of glass and skeleton frames of steel of modern aviation facilities.
John Vincent 