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Author Topic: VMO on the speed tape - Part 2  (Read 1198 times)


  • Join date: Oct 2014
  • Location: Amsterdam
  • Posts: 132
Re: VMO on the speed tape - Part 2
« Reply #20 on: Sat, 20 Jul 2019 18:50 »
Sorry for not having replied to this a little earlier (I have been busy for several weeks now with the sad things in life, that at some point we will all have to face). But...:

On the internet the JAA website can still be accessed, although for historical reference only: (https://web.archive.org/web/20110629013950/http://www.jaa.nl/introduction/introduction.html), and I'll insert one quote below with similar quotes available on Skybrary and Wikipedia:

JAA's functions were:

The JAA's work began in 1970 (when it was known as the Joint Airworthiness Authorities).  Originally its objectives were only to produce common certification codes for large aeroplanes and for engines.  This was in order to meet the needs of European Industry and particularly for products manufactured by international consortia (e.g. Airbus).  Since 1987 its work has been extended to operations, maintenance, licensing and certification/design standards for all classes of aircraft.  With the adoption of the Regulation (EC) No 1592/2002 by the European Parliament and the Council of the European Union (EU) and the subsequent set up of the European Aviation Safety Agency (EASA) a new regulatory framework was created in European aviation.

Before the inception of the Joint Aviation Authorities, each and every (European) country had its own National Aviation Authority. In the UK: Civil Aviation Authority; in The Netherlands: Rijks Luchtvaart Dienst; in Germany: Luftfahrt Bundesamt (also called the Luftfahrt Behinderungsamt). Each country therefor also had its own national Aviation legislation.

The intention of the JAA was to obtain one European set of Aviation "Requirements". Aviation delegations of associated countries were discussing these requirements, but since governments were NOT involved, they did not instantly become regulations (legislation). Only after - mostly - extensive government involvement and discussions, these requirements could be adopted into national legislation to make it "judge-able". Skelsey pointed this out as well.

Flight Crew licensing, for example, was discussed for many years within the JAA, then another number of years within the Dutch government before it became legislated/regulated. My 1995 Dutch national license was converted into a JAA license in 1999 (?). And in 2014 it then became a EU license. My national and later JAA examiner authorization (representing the government during exams) eventually became a EU examiner certificate, basically making me liable for any damage to people and property.
I don't recall when JAA started discussing JAR-OPS, nor when they implemented it, but my guess on start of the discussion is: 1987 (see quote above). Formulated Requirements: several years later. Implementation within national legislation: again many years later! Individual countries, however, could still choose to stick to their own national legislation. If I remember well, Spain - the government - did not adopt JAR-OPS in the Spanish legislation (until EU-OPS became effective, and to which they eventually had to comply).

KLM/Martinair Cargo 747's (PH-CKA/CKB/CKC) are from 2003, hence certification through JAR-OPS (the AFM for these aircraft states 365 kts/M0,90). PH-MPS is a BCF-aircraft, that first (1990) flew for Singapore Airlines. Certification through the FAA. It's AFM states 365/M0,92.

The difference might be based on the definition of critical Mach-number, where one definition is "the speed of the aircraft as measured in undisturbed air, expressed as a Mach-number, where the speed of the air over the wings for the first time locally reaches M = 1". No shock waves yet. Another definition describes the speed, where due to shock waves (buffeting) the drag is rapidly increasing and the behavior of the aircraft is effected in roll and pitch (drag divergence critical mach-number). This obviously is at a higher free stream airspeed and is supposed to occur when "delta CD/delta Mach = 0,10.

I had no time yet to see Hardy's modification, but just saw that the numbers have increased again (thank you for those as well).