Aircraft Safety

Boeing 737 MAX aircraft, which experienced catastrophic crashes in 2017 and 2018, were grounded in March 2019 pending their recertification as being safe. Defective software correction is widely believed to offer the solution. However, the principle problem is not software, but vertical aerodynamic instability due to enlarged and forward-relocated engines of the Leading Edge Aviation Propulsion (LEAP) series. Already, nine months have passed without apparent Boeing work toward airframe modification, and at least several more such months are anticipated by FAA. This paper lists concerns indicating that recertification should be deferred pending physical redesign, to continue the tradition of passenger aircraft stability independent of software.

This paper presents the results of a research activity performed by Cranfield University to assess the potential of carrierphase
Global Navigation Satellite Systems (GNSS) for attitude determination and control of small to medium size
Unmanned Aerial Vehicles (UAV). Both deterministic and recursive (optimal estimation) algorithms are developed for
combining multiple attitude measurements obtained from different observation points (i.e., antenna locations), and their
efficiencies are tested in various dynamic conditions. The proposed algorithms converge rapidly and produce the required
output even during high dynamics manoeuvres. Results of theoretical performance analysis and simulation activities are
presented in this paper, with emphasis on the advantages of the GNSS interferometric approach in UAV applications (i.e.,
low cost, high data-rate, low volume/weight, low signal processing requirements, etc.). Modelling and simulation activities
focussed on the AEROSONDE UAV platform and considered the possible augmentation provided by interferometric
GNSS techniques to a low-cost and low-weight/volume integrated navigation system recently developed at Cranfield
University, which employs a Vision-based Navigation (VBN) system, a Micro-Electro-mechanical Sensor (MEMS) based
Inertial Measurement Unit (IMU) and code-range GNSS (i.e., GPS and GALILEO) for position and velocity computations.
The integrated VBN-IMU-GNSS (VIG) system is augmented by using the inteferometric GNSS Attitude Determination
(GAD) and a comparison of the performance achievable with the VIG and VIG/GAD integrated Navigation and Guidance
Systems (NGS) is presented. Finally, the data provided by these NGS are used to optimise the design of an hybrid
controller employing Fuzzy Logic and Proportional-Integral-Derivative (PID) techniques for the AEROSONDE UAV.

Boeing documents include employee statements that denigrate those who supervised and conducted the design of the faulty 737 MAX aircraft and its Maneuvering Characteristics Augmentation System (MCAS), leading to two airplane crashes. However, this paper suggests that the problem was primarily not with the line employees, but the top management and its role in establishing corporate culture.

Despite a relatively crowded literature about detection of power lines for aircraft safety, the works are mostly optimized with very few training images; some even use artificially generated images. The IR imaging case is even less utilized. The reason is clearly the tremendous workload to obtain real images. With this demand in mind, the authors cooperated with the Turkish Electricity Transmission Company (TEIAS) to obtain video captures from actual aircraft. Later, the authors made a thorough inspection over the video frames to isolate, capture and clean thousands of valuable images. In this content, 200 IR and 200 VL images are acquired and scaled to a size of 512x512. The IR folder contains IR images with power line, ground truths and overlay images of these images. The VL folder contains VL images with power line, ground truths and overlay images of these images. The IR and VL groups were deliberately constructed to contain both regular and especially confusing scenes. "TY...

Aim: Identification of risks following collisions between aircraft and birds, and exposure of socio-economic consequences after such incidents.
Introduction: Aircraft collisions, with small objects, present a serious problem in connection with the safety of passengers, cargo and technical equipment. Most common incidents involve collisions with birds. This article presents emerging hazards caused by birds and other small objects, which collide with fast moving aircraft in the air or on the runway.
Methodology: Incidents known as “Foreign Object Damage” are illustrated historically with a particular emphasis on emerging trends found in current technical, environmental and organisational circumstances. The author analysed causes leading to the increased probability of bird collisions with aircraft and examined issues associated with the high risk of accidents aligned with an increase in air traffic volume and bird acclimatisation to prevailing environments in the vicinity of airports. The article contains data about frequency of collisions and associated causes. An analysis was performed on data in respect of civil as well as military aviation, with a particular
emphasis placed on information derived from USA and Great Britain. The author described approaches to minimise the risk of collision between aircraft and birds, and discussed the economical effectiveness of actions undertaken to manage the environment surrounding airports. The article highlights the role performed by international provisions covering risk mitigation, which define minimum norms, requirements and procedures regulating aircraft design, manufacturing processes, technical support, equipment use and awarding of
licences to staff.
Conclusions: The collision of aircraft with birds is a global problem and involves all elements associated with aviation. The author advanced an argument that the greatest potential for long-term efforts to reduce the risk of collisions between aircraft and birds lies in the design of safe airframe structures and engines which disperse as well as absorb energy created by the impact. This, accompanied by the development of ground-based and aircraft systems which, facilitate monitoring and prediction of bird behaviour, will which assist ground personnel and air crew in decision-making.

Recommendation of Eugenia Mbuña’s  MCAS IN THE BOEING 737 MAX

Robert M. Cutler

October 9, 2019

This paper is an excellent, concise introduction to the Boeing 737 Max crash history problem. It includes the Airbus competion cause, change to old 737s, added/hidden Maneuvering Characteristics Augmentation System (MACS), and lack of crew training/ignorance of MCAS turnoff causing fatal dives. Possible enhancements could mentions of the (1) lack of MCAS “critical” designation with three “voting” Angle of Attack (AoA) sensors/displays, (2) FIRST vertically unstable (nose-up and nose-down; both short-term and phugoid?) passenger airliner, (3) impaired maneuverability for high or gusty crosswinds/turbulence or impact avoidance, (4) larger engine, low-ground clearance runway/intake hazards, (5) need for airframe redesign e.g. longer landing gear, under-wing engines, and larger tail and (6) if no redesign, unfortunate precedents for future unstable aircraft and rewarding profit-over-safety.

I submitted a question regarding Boeing 737 Max re-certification some time ago; regretfully, the answer that was automatically promised has not arrived. This time, I will only ask if your re-certification team will carefully consider the points made by independent experts that show why simple changes involving only instrumentation, software, maintenance, and training are not suitable to replace some airframe redesign and re-designation (outside of the 737 series) for passive aerodynamic vertical stability-as with other airline passenger craft, avoiding possible problems from reduced maneuverability under a range of challenging conditions (nose up, level, or down), low ground clearance hazards, and new precedents for both unstable aircraft and rewards for putting short-term profit ahead of safety. One expert suggests longer landing gear, engine relocation back under the wings, and a larger tail. Such design change will take time and money, possibly requiring government support, but is best in the long term. Please ask the re-certification team to consider all of these factors and the supporting details, such as found at these three internet links: https://www.theverge.com/2019/5/2/18518176/boeing-737-max-crash-problems-human-error-mcas-faa (a comprehensive accident explanation at all levels) AND https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-737-max-disaster-looks-to-a-software-developer.amp.html (the author is also a pilot) AND http://nymag.com/intelligencer/2019/03/is-the-boeing-737-max-worth-saving.html (which suggests the redesign above). Also please reply to confirm full consideration of the facts and priority of safety. Thank you!

A naive perspective on outcomes would hold that decisions are always vindicated by the outcomes that follow them. However there are a number of situations where this idea does not hold.  These are situations where risk needs to be managed. Even though a positive outcome has been achieved, if too great a risk was taken in achieving it, decision-making is not vindicated by the outcome.

The examples of: mountain climbing; the US Federal Reserve setting interest rates; and aircraft safety are used to illustrate this point. This issue is discussed in terms of principles from outcomes theory - the theory of identifying, measuring, prioritizing and holding parties to account for outcomes of any type (http://doview.com/outcomes-theory-simplified).

Read this Linkedin Pluse article at https://www.linkedin.com/pulse/when-success-enough-whether-youre-mountain-climbing-us-duignan-phd.

Follow my work http://twitter.com/paulduignan.

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