Bicester Aviation Services

FAQs on GPS Systems and Flight Recorders

1.   I have heard that the IGC Approval of some IGC approved flight recorders will be downgraded from 1 October 2012. What impact is this likely to have on using it to validate Badge flights?

The first flight recorders were designed during the mid 1990's and conformed to the security standards then prevailing.   These recorders could be used to validate all IGC flights, including World records.   During the last five years, the security standards have been increased, predominantly by requiring a security system based on a RSA or asymmetrical algorithm.   While all the recorders designed and marketed during the last five years comply, certain early models have a symmetrical security algorithm and/or problems with the mechanical security micro switch.

From 1 October 2012, the IGC has decreed that some early will have their IGC approval revoked.  These include the Print Technik GR1000, EW Models A, B and D (but not the EW Micro) and early models of the Filser LX20,   Other recorders such as the the Cambridge GPS10, GPS20 and GPS25, Colibri v1 through v4, and Zander GPS940 are downgraded to FAI Badges and Distance Diplomas only. 

2.   Can you explain how UK airspace is entered and updated in Glide Navigator II, See You and See You Mobile?

Glide Navigator imports airspace from the Tim Newport-Peace .air files.   These are published each year by Tim and published on the BGA website.   They can also be found in John Leibacher's World Soaring Turn Point Exchange.  

See you and See You Mobile use airspace files which are compiled specifically for the See You and LX Navigation products.   These files have a .cub extension (See You binary) and can be found on both the See You and LX Navigation web sites.   Alternatively, they can be compiled using a compiler, LX Airspace Browser.   This free program compiles airspace from a variety of formats including the Tim Newport Peace version and the  DAFIF format.   Both these formats are ASCI text formats and can, if required, be easily modified with a simple word processor before compilation.

3.   Why does my IGC approved flight recorder have two serial numbers?

When the International Gliding Commission (IGC) created the standards for approved flight recorders, they decreed that the serial numbers would be a trigraph consisting of three alpha numeric characters using the numbers 0 to 9 and the letters A to Z. These three character alpha numeric serial numbers are mathematically described as 'base 36' numbers, and use the digits 0 to 9, with 10 represented as 'A', 11 as 'B' etc to 35 represented as 'Z'. They can be converted to an equivalent base 10 number which only uses the characters 0 to 9, and which we all recognize. This means that every IGC approved flight recorder will have both an alpha numeric base 36 three character serial number, as well as an equivalent base 10 numeric serial number. Flight recorders manufactured by Cambridge and Volkslogger were all assigned a base 36 three character serial number when built. However, the early recorders made by Filser, EW and LX Navigation carried the base 10 serial number. This is converted to a base 36 number when the IGC file is downloaded. For example, a LX Colibri may be designated with a base 10 serial number of 15657. This is equivalent to a base 36 serial number C2X.  In the fullness of time, all base 10 serial numbers will be displayed as base 36 three character serial numbers.  In passing, it should be noted that a flight recorder can have a base 36 number comprised of all numeric characters.  For example a Cambridge recorder might carry the S/No 535.  This is a base 36 number and equates to a base 10 S/No of 6593.  Still confused?  

The .IGC files that are generated by an IGC approved flight recorder will always have a file name of xxxxxxxx.IGC where the 'x' are decoded as follows:

The first character represents the last digit of the year the flight was made.  For a flight made in 2005 (or 1995) this digit will be 5.

The second character represents the month of the flight.  1 to 9 denote Jan to Sep respectively, while Oct is denoted by 'A', Nov by 'B' and Dec by 'C'.

The third character represents the day of the month.  1 to 9 denote the first 9 days of the month, while the 10th is denoted by 'A', the 11th by 'B' and so on, until the 31st which is denoted by 'V'.

The fourth character is a single letter denoting the manufacturer of the flight recorder.  'A' denotes Garrecht (Volkslogger), 'C' Cambridge, 'E' EW Avionics, 'F' Filser, 'L' LX Navigation, 'P' Peschges and so on.

The fifth, sixth and seventh characters is the base 36 alpha numeric serial number of the flight recorder.

The eighth digit represents the number of the flight on any day