The following are for timers with revised firmware. Operating instructions for the original version: Click Here

The WTT4 and WTT5 are dual, independent wake turbulence timers to aid Air Traffic Controllers in maintaining plane separation during takeoff. The timers are designed to integrate easily into their process without adding to their cognitive burden. The color-coded displays and buttons shapes allow glance-able confirmation of the countdown period selected. 

The WTT4 and WTT5 differ only in the format of the panel - the WTT4 features two timers side-by-side in a horizontal format while the WTT5 features two timers stacked one above the other in a vertical format. 

  • Color-coded timer sections for easy differentiation when both sections are in use. 
  • Two fully independent timers 
  • Countdown intervals of 2 and 3 minutes and optionally extended periods of 4 and 5 minutes (enabled by a jumper) 
  • Large, easy to read 7-segment LED displays show remaining time in countdown period.  
  • Simple two-button interface to initiate a countdown. 
  • Instant countdown cancel and restart with new time period (revised version).  
  • Instant countdown cancel and return to idle state.  
  • Distinct audio alerts for each timer section at the end of a countdown.  
  • 16 brightness levels for the 7-segment LED displays and button indicators accommodate the range of operating conditions.  
  • A lamp test shows proper operation of all display segments and switch indicators.  
  • A switch test is available to verify proper switch operation and freedom from sticky or intermittent operation.
Basic Operation

Click To Enlarge.

Setting Display Brightness and Beeper Volume Levels

Display may be adjusted to 16 levels to accommodate changing light levels in the cab. Beeper volume may be adjusted ovver a wide range if the optional audio beeper board is installed. 

To enter the settings menu press the DIM switch when both timers are idle. 

The timer will show dSP in the yellow display, and if the audio card is installed, Snd in the red display.


Pressing either of the yellow buttons results in display of the current brightness setting from 0 (dim) to 15 (bright). Pressing the left yellow button decreases the brightness, the right yellow button increases it. The displays and buttons will show the adjusted level. Press the DIM switch when the desired level is set. 

Pressing one of the red buttons enters the volume adjust menu and shows the current level. Pressing the left red button decreases the volume; pressing the right red button increases it. The beeper will sound momentarily each time a button is pressed so you can judge the level. Press the DIM switch when the desired level is set. 

Lamp Test

A lamp test is performed each time power is applied to the timer or the reset switch is pressed. All displays segments and switch indicators will flash several times and the beeper will sound. To Initiate a lamp test, insert a toothpick into the reset switch hole on the panel and press gently; the lamp test will start after a two second delay. The lamp test runs for several seconds, returning the timer to normal operation.

Switch Test

The switch test tests switches for intermittent or sticky operation. Initiate a switch test by pressing and holding the DIM switch while pressing and releasing the reset switch (described above). 
When a switch is pressed, the switch will illuminate, the beeper will sound and the display will show which switch is pressed. This should happen as soon as the switch is pressed, and stop the instant the switch is released. If operation is intermittent, delayed when pressing the switch or continues after releasing the switch, the switch should be replaced.