Page 28 - May23T

Decide
From the Flight Deck
by Kevin R. Dingman
Aircraft High-Speed Aborts, Dopamine and Time in a Bottle
Super 80 on takeoff. It’s sometimes better to continue rather than abort.
PHOTOS BY AUTHOR
Before we begin this month’s story about the decision to abort or continue a takeoff, and before explaining our eccentric subtitle, we should thoroughly understand
these takeoff-distance definitions:
Accelerate-go distance is the total distance to acceler-
ate from a stop, lose an engine (or other reject criteria) just before V1, recognize the failure as you reach V1, and continue the takeoff to cross 35 feet AGL at the end of the runway and at your takeoff safety speed (V2). Note: after liftoff, if your airspeed is slower than V2, pitch to acceler- ate to and maintain V2. If your airspeed is faster than V2, pitch to maintain an airspeed no faster than V2 + 10. Some flight guidance systems will recognize an engine failure and display this profile through the flight director’s V-bars.
Accelerate-stop distance includes the total distance to accelerate from a stop, lose an engine (or other reject criteria) just before V1, recognize the need to reject as you reach V1 (officially, a three-second delay is acknowl- edged, but the reject must begin at or before V1) and stop
26 • TWIN & TURBINE / May 2023
the airplane using idle thrust, wheel brakes and speed brakes/spoilers before reaching the end of the runway. Note: most aircraft performance data for an abort (reject) do not include using thrust reverse, so if used, a single thrust re- verser (single engine, remember?) is a bonus in reducing stopping distance, but directional control may become an issue. Also, the commonly accepted order (after throttles idle) for the use of deceleration devices is: 1. max braking and 2. simultaneously deploy speed brakes & spoilers, and then 3. thrust reverse.
Balanced field length is where the accelerate-go and accelerate-stop distances are identical.
Now that we’ve had our refresher, on to the story.
The most difficult thing is
the decision to act; the rest
is merely tenacity. -Amelia Earhart