Flight Recorder Calibration
On January 15, 2010 Cumulus Soaring, Inc. received approval from the Soaring Society of America as an approved GPS flight recorder and barograph calibration lab.  

I do my best to provide the best GPS Flight Recorder calibrations available anywhere.  My calibration runs go up to 60,000 feet, and I provide more useful calibration data. 

The output of the calibration run is a set of 5 calibration data sheets.  Printed versions are sent to you with the unit.  I also email the data sheets to you - to make it easy to forward them to an Official Observer and to the badge and record verification person.

Calibration DocumentCalibration-2024-01-05-Nano3-KX7.pdf

Calibration Excel SpreadsheetCalibration-2024-01-05-Nano3-KX7-Spreadsheet.xlsm

  • Calibration Table
    The data from the calibration run - in both feet and meters

  • Calibration Graph
    An easy to read graph for converting altitudes measured in flight to calibrated altitudes.  Most other calibration labs do not include this graph.  I provide versions in both units of feet and meters.

  • Calibration Barogram
    The plot of pressure altitude versus time that was recorded during the calibration run. I include versions in both units of feet and meters.

  • Calibration Excel Spreadsheet
    This is the Excel spreadsheet I use when creating the calibration documents.  It includes a very handy utility which allows you to enter an altitude from the flight log, and the spreadsheet uses the calibration table to calculate the calibrated altitude.  Alternatively, you can enter the desired actual flight altitude, and the spreadsheet will use the calibration table to calculate the altitude you would see on your GPS Flight Recorder.

Brands Supported
I am able to calibrate all brands and types of barographs and flight recorders.  I can calibrated and re-seal the brands listed below.

  • Cambridge GPS-NAV, 302, 302A
  • ClearNav Flight Computer, ClearNav II Flight Computer, ClearNav CNv Variometer
  • EW: Model D, microRecorder
  • FLARM: Classic FLARM, PowerFLARM Core, PowerFLARM Portable, PowerFLARM Fusion
  • Garrecht Volkslogger
  • LX Navigation: Colibri, Colibri II, LX20, DX50, LX5000, LX7000, LX7007, Era, Zeus
  • LXNAV: S10, S100, LX8000, LX8030, LX8040, LX8080, LX9000, LX9050, LX9070, Nano, Nano3, Nano4, PowerMouse
  • Naviter Oudie IGC, Oudie N IGC

Fast Service
I realize that there are times when calibrations are needed urgently.  1 day service is standard.

Barographs must be calibrated every year and GPS Flight Recorders must be calibrated every 5 years.  Calibration is necessary if you are using the unit as flight evidence for badge or record flights.

Please include a check for $95 plus the estimated return shipping cost.  UPS Ground is usually less than $25 (with insurance).  If you overpay I will include a refund check in the box with the unit.

Quantity Discounts
I can put many flight recorders into the calibration chamber at one time and make a single calibration run. That saves me considerable time. However the paperwork still takes time for each individual unit. I therefore offer the discounts below when I receive multiple units for calibration at once. You also save money on shipping costs when you send multiple loggers to me in one shipment. The discounts only apply to units shipped to me in a single box and paid for with a single check. The units must also be shipped back to a single address.

  • 1 unit: $95
  • 2 units: $90 each
  • 3 units: $85 each
  • 4 units: $80 each
  • 5 or more units: $75 each

Shipping Address
The shipping address is on the bottom of every page on this web site.

Please include a note in the box with the information listed below.  I can't send it back to you if I don't have your name and address.  I can't contact you with questions if you don't include your phone number or e-mail address.

  • Name
  • Address
  • e-mail
  • Phone Number
  • Barograph or Flight Recorder Type and Serial Number
  • Desired return shipping method (UPS Ground is standard)

Calibration Altitude Conversion Spreadsheet - 
FREE Download
This is a very handy Excel spreadsheet which allows you to enter an altitude from the flight log, and the spreadsheet uses the calibration table (entered manually) to calculate the calibrated altitude.  Alternatively, you can enter the desired actual flight altitude, and the spreadsheet will use the calibration table to calculate the altitude you would see on your GPS Flight Recorder.

Calibration News

Updates to the Sporting Code in October of 2023
The SSA published the information below in late 2023.  If I understand correctly, as of October of 2023, badge flight validation no longer requires calibration of flight recorders every 5 years.  I think that state, national, and world soaring records and international soaring contests still require calibration every 5 years.  The new rules are both more simple, and more complex.  I have copied below the information provided by the SSA.

Sporting Code: 
On the page in the link above, select:

  • "SPORTING CODE - SECTION 3: Gliding"
  • Current Sporting Code for Gliding
  • Sporting Code Section 3


2.4.6 Barometric calibration period Calibration requirement of the barometric recording function varies with the claimed task as follows:   

a. Silver or Gold claims using an FR or PR with no calibration data – 2.4.3c applies.   

b. Silver, Gold, Diamond Goal & Diamond Distance claims using an FR having calibration data – no periodic calibration needed but the most recent calibration shall be used.   

c. Diamond Altitude & Diploma claims – FR shall be calibrated within 5 years prior to the flight or within 2 months after the flight.   

2.4.3 Altitude evidence GPS altitudes use the WGS84 Ellipsoid as the GPS altitude zero datum. 

a. A copy of the calibration certificate of each FR used shall be submitted with the claim. The pressure altitude evidence is to be corrected using the calibration chart data when the precise altitude is critical to the claim (see 4.3.4c). 

b. The altitude at which a glider crosses a start or finish line is determined by linear interpolation between the altitude at the last fix before crossing and the first fix after crossing. 

c. If PR barometric data is not available or the FR calibration period has lapsed, GPS height data may be used for Silver and Gold claims, provided that a 100 meter error margin is applied to all pressure height requirements of the Code (example: the gain of height is at least 1100 meters for Silver altitude).   An example is given in SC3C-3.3. 

 4.3.3 Post-flight control actions If the OO was NOT present at take-off (see §4.3.1), an OO must observe the landing to confirm the pilot name(s) and glider ID. For all controlled FR/PRs, an OO shall inspect any seals applied before take-off and perform or supervise the data transfer. Claim submission shall be performed by that OO or another qualified person who shall submit:

 The original data on the memory device as soon as possible after landing. This must include the .igc file and the device file in its original format (if different) for all controlled FR/PRs installed, even from a failed device. The claim shall include a copy of the calibration certificate for each .igc file submitted for analysis per the requirements given in 2.4.6 or 3.3.5.

The appropriate claim form(s), including OO’s evidence that any manually recorded times and locations for the flight correspond to the equivalent FR/PR data.

*** All record flights still require calibration every 5 years.  - Rollin Hasness, SSA Badge & Record Keeper

IGC Calibration Requirement Frequency Change - October 2013

In the past, IGC rules required GPS flight recorders to be calibrated every 2 years. In October of 2013 the IGC changed the rule - requiring GPS flight recorders to be calibrated every 5 years. It does not matter whether your last calibration was done before or after October 2013. To use it for badge or record verification it must have been calibrated within 5 years. For some badges and records it is acceptable to get the calibration done after flight (within 60 days?). However, some national and world altitude records require calibration both before (within 5 years) and after (within 30 days?) the flight. The new 5 year fule is in section 4.4.4 in the 2013 edition of the Sporting Code, Section 3.

Send your unit to me and I will calibrate it quickly and accurately. I work hard to provide the most accurate, detailed and highest altitude calibration data available. My calibration system can go up to more than 60,000+ feet (as you can see in the data sheets at right). Note: Not all GPS flight recorders record altitudes that high, but many do.

My calibration lab meets all the requirements put forward by the SSA for Category 2 Calibration Labs.  You can see details on the SSA web site here:

I also follow all the procedures and requirements set forward by the FAI in the Sporting Code Section 3 (Gliding), Annex C ("Official Observer & Pilot Guide"), Section 11 ("Flight Recorders - Calibration Procedure") which is available here:



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