Saturday, September 29, 2018

Plane crashes in aviation history

Definition of a plane crash

An air accident, also known as "plane crash", is an event related to the operation of an aircraft that results in the death or serious injury to one or more persons and often irreparable damage to the body shell of the aircraft. An event involving flight safety without serious consequences is considered an air incident. The term air disaster is used by the media, especially for accidents involving an airliner. In most accidents is only one plane involved. Mid-air collisions of two planes are rare. The attacks on the World Trade Center (WTC) 9/11 are not considered air accidents.

States may establish an authority to ensure flight safety and accident investigation. These agencies, as well as a few non-governmental organizations, maintain databases whose purpose is to advance security. All American airlines, be it Delta Air Lines or United Airlines experienced fatal crashes.

The main reason is bad weather in combination with human error misjudging the thunderstorm in front. Other problems of human errors include not to communicate in the cockpit. Problems leading to structural damage include design flaws, material fatigue or mistakes in maintenance of an airplane.

The development of statistics groups air accidents according to various criteria, thus makes it possible to raise the awareness of manufacturers, operators, crew, air traffic controllers, maintenance personal and others by identifying the primary or secondary causes of accidents.

  • Destruction of the plane in flight: collision between two planes, major structural defect, fire, terrorist attack, interception by the Air Defense of the country overflown
  • Destruction of the structure on impact with the ground, better known as "crash": navigation error and striking an obstacle, serious mechanical incident forcing the pilot to attempt an emergency landing
  • Ground accidents: collision between a plane in take-off or landing with another aircraft that has entered the runway

The vast majority of accidents concern general aviation but the media and the public are mainly interested in accidents involving airliners.

The International Civil Aviation Organization - ICAO

The ICAO definitions and the resulting statistics relate to motorized aircraft used by organizations or civil companies. States relying on ICAO recommendations to establish an investigative agency may, however, extend the scope of the jurisdiction to include non-motorized aircraft accidents, unmanned aircraft on board and military uses, but excluding related cases.

Aim of the ICAO is the recommendation of an accident analysis process to investigate the causes and to derive actions to improve safety. The accident report establishes the primary cause and, often, the sequence of secondary causes that contributed to the problem. These conclusions are of interest to manufacturers and equipment manufacturers, airlines or operators, crews, navigation controllers and maintenance services. The determination of responsibilities does not fall within the scope of investigations.

The term "disaster" does not appear in the official texts but appears in the media when the accident concerns the commercial air transport of passengers. The notion of "catastrophe" is also changing in relation to the increase in traffic and the increase in the size of aircraft.

General aviation and, in particular, light aviation generate far more accidents than air transport, but they are rarely the subject of media coverage at the national level. Air accidents related to military activities, training and missions outside conflict, are rarely the subject of a report made public that could reveal classified information.

Aircraft accident investigations aim to improve flight safety. An accident rarely has a single cause. Unofficial reports or databases compiling accidents most often identify a determining cause, but the report of the investigative office looks for the causes that generate or participate in the determining cause as well as the errors of perception or action that did not allow corrections or palliatives. The report is used by the Official Services to modify the standards and by the manufacturers, operators, crews, air traffic control service and maintenance workshops to modify the procedures. In principle, the report of the investigative office does not determine the responsibilities but is an essential element for any legal action.

Wednesday, September 5, 2018

Stingray underrated

There is a movie from 2019 called Stingray, also known as Raymond, starring Joel Edgerton, Jon Bernthal and Anthony Hayes. I wonder if this is a sequel to the series by the same name which was originally aired in two seasons from 1985 to 1987 with a pilot of 90 minutes from 1984, featuring Canadian Actor Nick Mancuso, which I want to talk about.

I didn't watch it then. May be I thought it's another series with a talking car full of electronics. I thought of Knight Rider's K.I.T.T. Also Street Hawk, the series with an experimental super bike, came to my mind so I just ignored it.

Recently someone on Youtube showed a video composed of 1980s intros of shows loved by us teens then. Stingray was among them. I was instantly hooked by the musical score. Sounded to me like straight from Miami Vice and Jan Hammer on the keyboard. Instead it was done by Mike Post, Pete Carpenter, and Walter Murphy. Amazing!

I ordered a DVD set and enjoyed this short lived US series. "Ray", as he was called by others, is untouchable and almost always has full control of any situation. Even when it seemed he now takes some beating or was betrayed he will come out on top instead. Then he vanishes silently and without a trace like he appeared. He only revealed his real name once by whispering into the ear of somebody so the audience wouldn't know.

The series was well underrated. May be the move to the filming location in Vancouver in Canada, with its bad weather conditions in the second season and thus bad plots, led to the series cancellation. Too bad. If it would had stayed in sunny California it would had deserved a third season in my opinion.

Sunday, September 2, 2018

CP/M, the first operating system

The operating system CP/M

CP/M, the acronym for Control Program/Monitor or Microcomputer, is an operating system created in the year 1974 by Gary Kildall, founder of Digital Research. It is used on 8-bit Amstrad CPC and Amstrad PCW, Commodore 128, TRS-80, Osborne 1, BBC Micro, ZX Spectrum. It also found use on PCs, including the standard Amstrad PC-1512 in addition to MS-DOS and GEM.

For the Apple II, Microsoft created in 1980 the Z-80 Soft Card expansion card that allowed the use of the operating system of Digital Research. Early versions of MS-DOS were largely inspired, if not copied by CP/M.

Organization of memory

The memory of a computer under CP/M is divided into four parts:

  • BIOS: The Basic Input Output System for serial peripherals. It handles peripherals, floppy disks, monitor printers, etc. Usually, the BIOS occupies the "high" part of the memory.
  • BDOS: The basic disk operating system primitives. It contains the operating system. Usually, the BDOS is under the BIOS.
  • CCP (console command processor): Usually, the CCP is under the BDOS. This part of the CP/M corresponds to the user interface.
  • TPA (transient program area): This part of the memory starts at 100 (hexadecimal address). It is intended for user programs.

The different types of files

CP/M system stores files on floppy disks according to a specific logical organization, which has not been taken over by MS-DOS and can fill the disks. CP/M can also handle hard disks. In fact, as the BIOS is open, as clearly described in the documentation that Digital Research provided with some of its software, so it is possible to adapt any particular CP/M system to any available mass memory and devices available. Some computers running CP/M were originally sold with hard drives. Altos is one example.

Each file has a name and an extension.

  • ASM: assembler source file
  • PRN: assembler listing file
  • HEX: Machine language presented as a series of hexadecimal octets in Intel format
  • BAS: BASIC source file
  • INT: intermediate basic file
  • COM: command file, memory dump file, starting at address 100 hexadecimal under CP/M. Executable files always have the extension .COM
  • SUB: a file with a sequence of commands to be processed in batch mode by the command SUBMIT.
  • BAK: backup file is often used by word processing programs
  • $$$: temporary file, used for example by SUBMIT
  • LBR: archive file

Different orders of CP/M

CP/M commands can be internal or external, as was subsequently the case with MS-DOS. For the user under CP/M there is no difference between launching an internal command, such as DIR as *. * or an External like STAT as *. *. Or any other program.

Under CP/M, the shortest program needs only one byte, which returns to the System. On the other hand, it must be saved as an executable file using a .com extension, whose minimum size is one sector with a 128 bytes minimum.

The external commands of the CP/M or MP/M called programs of the same name which had the extension .COM or .PRL (only in the case of MP/M). Additional information: the MP/M was similar to CP/M but with a multi-user functionality.