Failed AWTT3 Timer and Substitute Timers prior to WTT4 Installation

What's a wake turbulence timer?

Plane takeoffs are separated by time so that a following aircraft isn't buffeted about or even tossed around by the wake of the lead aircraft.  The interval between planes depends on the relative sizes of the planes and other parameters.

Since the mid-70s, in the FAA Northwest Mountain Region, electronic wake turbulence timers have been used by Air Traffic Controllers in the important task of maintaining aircraft separation.

What are the alternatives to wake turbulence timers?

Various methods are in use, including watching the sweep second hand of a clock, using a stopwatch or even using "hourglass" egg timers.  While these methods work, they can be a distraction from more important details an Air Traffic Controller must contend with.

What's the story with the WTT4 and WTT5 Wake Turbulence Timers?

 The wake turbulence timers installed at airports in the Western Mountain Region had become unserviceable and could not be economically repaired.  The WTT4 and WTT5, differing only in format, were developed as replacements.  Reliability and a long service life were driving factors in the design.  The timers provide 2 minute, 3 minute, 4 minute and 5 minute periods required by the Recat instruction.

The timers have been in use for more than 2 years at 10 airports in the Western Mountain Region including Seattle-Tacoma International Airport, Boeing Field and Paine Field, and were subject to a year-long evaluation period at those airports which received  glowing reviews.  Since the timers have been in service, no failures or errors in operation have been observed.

There have been proposals to permit the timers in control towers as well as to require them.  Due to inertia within the FAA, these proposals have languished in the review process and are essentially dead now.  The decision to install and use wake turbulence timers rests with each control tower.


What are the features of the WTT4 and WTT5?

Dual independent color-coded timers

Single button press to initiate 2 minute, 3 minute, 4 minute and 5 minute countdowns

Large visible 7-segment LED displays show remaining time of the countdowns

Distinctive audible indication of countdown completion for each timer section

Single button cancel and restart for waived wake turbulence

Designed for long term reliability and serviceability.


What alternatives for wake turbulence timers are available?

The WTT4 and WTT5 Wake Turbulence Timers are a proven product, having been in use at major airports for more than two years and have undergone a year-long FAA evaluation.  Installation is simple and operation easy to understand with a few minute's use.

As far as we know, aside from one or two hobby projects, no other electronic wake turbulence timers are in use in the US.

There has been discussion of adding a wake turbulence timer function to the NexGen system but no funds have been allocated to do so and no programming resources are available so any implementation is years away at best.  Feedback from Air Traffic Controllers is that they prefer a single-touch, always visible wake turbulence timer to one which may require navigation of several screens  to initiate a countdown and toggling between screens to see the remaining time.

Why use wake turbulence timers over other methods?

The primary reason is pretty simple.  Wake turbulence timers allow Air Traffic Controllers to focus on important details instead of watching sand fall through a timer or watching the sweep second hand of a clock or stopwatch.  A single button press starts a countdown of the required duration with remaining time easily visible on large LED displays, with a gentle audible reminder when the countdown is complete.

Air traffic safety may be improved when using wake turbulence timers.  The proper interval is selected with one button press so there's no confusion about what the countdown period was selected or how many times a sweep second hand has gone around a clock.  The time periods required by the Recat instruction are instantly available.

Finally, as busy airports, airport throughput can be improved because timing intervals are accurate.  A few seconds lost on each takeoff caused by not noticing the last grain of sand has trickled through the hourglass or by rounding times on the sweep second hand add up over the course of a day.

What next?

Please review the tabs above for specifications, operation and installation instructions and purchase information.  Air Traffic Controllers in the Northwest Mountain Region love these wake turbulence timers - when it was suggested that they be removed after the one year evaluation period, the response was a very adamant No!  

If you have any questions, feel free to email Clever4Hire.