From Hang Gliding Wiki
Jump to: navigation, search


This document shows the various ways the Flytec instrument displays Vario and McCready ("MC") Speed-to-fly "STF" information and also describes the MC audio function. This document expands on Sections 4.10, 10.4, 10.5, 10.6 of the Flytec 5030 manual v 2.24 (and the similar, I presume, sections of the 6030 manual)

The Flytec instrument shows Vario and McCready ("MC") Speed-to-fly "STF" information in a graphical/analog format that allows the pilot to understand and use the information without having to read and interpret numbers nor does the pilot need to be concerned with the difference between true and indicated airspeed as the MC indicator takes that into consideration.

Numbers represent feet per minute "fpm".

The MC is accurate if you have the correct polar in the instrument. Polar acquisition/generation will not be covered in the document. Your glider manufacturer should be able to get you a polar close enough to general use.

The simulation mode of this instrument is a great way to experience these features.

If anything in this document needs revision or could be written differently so its easier to understand, please contact me at Andrew Vanis 505-304-5306

Thanks to Davis Straub for reviewing an early version of this document (read as: all errors after his review are mineJ) and to Steve Kroop at for the continual service.

Jay Rebbeck's XC Magazine Article is good reading: Hang Gliding Techniques: Speed to Fly and other Myths



Climbing = 520


Sinking = 280


Climbing = 80
Last thermal = 300

The instrument can be configured for the length of climbing time that is used to calculate this displayed amount.

McCready "MC" (non-audio)


The circled areas are the MC indicator. The MC indicator is present at any time the pilot is flying.

MC uses the aircraft polar to indicate what speed a pilot should fly depending on what the pilot wants to achieve. Using this display a pilot does not need to know what actual speed to fly or if/how altitude affects the speed to fly, the pilot just needs to look at the MC indicator (see note 6 at end of document for IAS/TAS info).

When on glide using the MC indicator there is no need to look at the climbing or sinking information since the MC calculation takes this into consideration.

When circling, the MC indicator is of little use and the best flying speed for the best climb is still minimum sink (see note 3 at end of document).

Best Glide


MC = 0
Sinking = 150
Last thermal = 300

At MC = 0 the pilot is flying at best glide.

This MC will get the pilot to a location with the most altitude or allows the pilot to get the most distance from any starting altitude.

Flying too slow - don't do this


MC = - 330
Sinking = 200
Last thermal = 300

Here the pilot is flying too slow. Flying a negative MC loses the pilot altitude AND time compared to flying MC=0. Don't do this.

Flying expecting the same strength thermal as the last thermal


MC = 300
Sinking = 80
Last thermal = 300

Here the pilot is flying as if he is expecting that the next thermal will be 300fpm.

This is used when cruising in the middle of the day and expects the next thermal to be as strong as the last thermal. He is flying faster than best glide and though he will lose more altitude between thermals, however, the strength of the thermal will make up for the altitude loss and the pilot will ultimately end up at any given distance at a faster time than flying at best glide. This of course works only when the next thermal is actually there at the expected strength. If the next thermal is weaker (or not there) the pilot lost the speed/altitude gamble and arrives with less altitude. If the next thermal is stronger, then the pilot could have flown faster to that stronger thermal.

Flying expecting a stronger thermal than the last thermal


MC = 500
Sinking = 80
Last thermal = 300

Here the pilot is flying as if he is expecting that the next thermal will be 500fpm. Maybe the last thermal was early in the day and the pilot expects the thermals to get stronger or the pilot is flying towards an area known to have a 500fpm thermal (like his friend just radioed a location of a thermal of 500fpm)

Flying expecting a weaker thermal than the last thermal


MC = 200
Sinking = 80
Last thermal = 300

Here the pilot is flying as if he is expecting that the next thermal will be 200fpm. This may be at the end of the day when the pilot expects the next thermal to be weaker than the last one.

McReady (With Audio)

FlytecSpeedToFly025.gifQuiet zone within thermal average

FlytecSpeedToFly027.gifQuiet zone outside of average

The MC audio allows the pilot to glide without needing to look at the instrument display. It is very helpful when looking for traffic or on fast glide when display is out of easy view.

To activate MC audio pilot flies his desired speed and puts the MC indicator to the value he wants to fly and presses the MC button. When the MC audio is on, the average thermal band turns solid black. In MC audio every region makes a distinct sound except the "quiet range" that indicates that the pilot is flying within the range he chose. If the quiet range is within the thermal band the quiet range is hatched (upper picture). If the quiet range is outside the thermal band it is not identified graphically (lower picture). The span of the quiet range can be chosen in the instrument set up.

The MC audio zone is active only when on glide (not climbing) and the length of time until it becomes active after climbing can be set in the instrument options so it does not get activated during a short time of sink while trying to thermal.


MC = in quiet zone = no sound
MC = higher than quiet zone = "slow down tone" - tone gets more pronounced the further the MC indicator is from the quiet zone
MC = lower than quiet zone (but not less than best glide, MC=0) = "speed up tone" - tone gets more pronounced the further the MC indicator is from the quiet zone
MC < 0 = distinct "SPEED UP - less than best glide" tone. This tone is significantly different than the "speed up tone" above. This tone also gets more pronounced the further the MC indicator is in the -MC range

In quiet zone


Here the pilot hears no tone and should continue flying this speed.

Flying faster than quiet zone


Here the pilot is flying faster than the quiet zone he chose and hears a "slow down" tone.

Flying slower than quiet zone


Here the pilot is flying slower than the quiet zone he chose and hears a "speed up" tone.

Flying slower than MC=0 (Best glide)


Here the pilot is flying slower than MC=0 (best glide) and hears the distinct "SPEED UP - less than best glide" tone.


These notes point out anomalies and/or areas I still don't completely understand and/or limitations of this instrument. These areas are minuscule and should not affect the general usefulness of this instrument.

  1. The climbing/sinking scale automatically changes from the lower range of 0-800fpm to the upper 800-1600fpm when the instrument is outputting data in the upper range.
  2. The thermal average band only shows in the lower range. Even when the instrument is in the upper range, the thermal average indicates as if the lower range is still active. 1) remember this when the instrument is in the upper range 2) that average climbs greater than 800fpm will display only up to 800fpm. Non-technical explanation - I'm guessing this was done for technical reasons and that for the small percentage of us that are lucky enough to have average climbs above 800fpm should consider ourselves lucky and the day is so strong we can fly pretty much any speed a HG can fly and still have a great day.
  3. The MC indicator shows while climbing only when above the current climb rate. I am still not clear on the logic here however it is supposed to indicate that you are flying faster than optimally for an efficient climb. How this is figured I am not clear 1) one needs to fly a speed adequate for good glider control 2) best clime is always at minimum sink 2) min sink airspeed increases with bank angle so without the instrument knowing your bank angle it cannot accurately calculate min sink speed. There may be times that MC while climbing may be useful say, when dolphin flying under a cloud street, however the technology may limit these calculations. In general, I am led to believe that the MC indicator while climbing is just displayed as a "Hey, consider that you may be flying too fast" reminder and not specific to any certain flying efficiency data.
  4. The MC audio goes silent when flying a speed (way too slow) that you are flying at a MC lower than the current sink rate.
    Hopefully one would notice this as it is happening however I guess it would be possible that a pilot could be flying in the quiet zone and enters a mass of air that all of the sudden he is flying a MC lower than the sink rate and still hears quiet, concluding incorrectly that he is still flying at his quiet zone speed when in fact he is flying way too slow.
  5. This display also eliminates the need for the pilot to understand the differences between Indicated Airspeed ("IAS") and True Airspeed ("TAS") When a glider manufacturer states a best glide at 25mph, that speed is at a standard atmosphere (sea level). A pilot flying in no wind at 16,000ft using the IAS display will still get best glide when the speed display shows 25mph but a pilot using the TAS display needs to fly a speed where the speed display shows 33mph. The MC indicator indicates the speed to fly no matter what the altitude.
  6. This MC indicator could be used with the LD reg/ LD ground that some pilots like to use, just fly the LD ground setting you like and press the MC button. The audio feedback will be the same.