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Unless engine parameters fluctuate, a bird strike typically does not warrant an abort.
Black and white is easy; gray is much more difficult. Fires, engine failures or flight control problems are easy; they’re all on a short list of reasons to stop. A sickly engine that is dying a slow death, a funny noise or vibration, or a strong smell as you approach V1 means you must use judgment and decide; is it safer to fly or stop? (more in a bit about botching the abort) You’re the one that must decide, often in a hurry. The decision is made using the knowledge, train- ing, current conditions and experience you can muster in the few seconds you have before V1.



#%&'(
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There I Was
I was trying to analyze, rationalize, and explain away the offending engine parameter as being ‘close enough’ so that we could continue. Continue how we have for the last eight or nine thousand takeoffs, comparing left to right and assessing limitations. Why won’t it just quit—or give me a fire light, an overtemp, or at least something out of limits?
I know this airplane better than I’ve known any other machine in my life, better than the back of my hand. I know what close enough looks like. Maybe this is close enough. Nope, this is not close enough—in fact, it’s getting worse, further away from ‘close enough.’ It’s acting too different from the previous nine-thousand times. The right engine N1 was slowly decreasing, and the EGT was increasing. In three seconds, it will be too late to stop. In another eight, it will quit; I know it will.
Reject! Throttles idle and max manual brakes. Verify the auto-spoilers deployed and throw out the buckets. My FO tells the tower we’re aborting as we’re pushed slightly forward into our shoulder harnesses. The instant I made the deci- sion, I was mad. Not mad at myself for making the wrong decision. Ironically, I was mad at the engine for not failing more definitively—more deliberately, more exuberantly. A dramatic failure that the passengers could see and be grateful that we stopped.
Dopamine Singularities
Everything you have read so far transpired in three seconds as we accelerated from 110 kts to 120 kts: 25 kts below V1. Seven seconds later, we were below 50 kts and had more than one-third of the runway remaining. I moved my hand from the yolk to the tiller and steered onto the high-speed taxiway at 20 kts, made a PA to the folks, and waited for ARFF to check us for hot brakes. Total elapsed time from brake release to taxi speed: 40 seconds. Perceived time: five minutes. I’ve had eight engine failures: two in the Duke and the rest in turbines—and two of the turbine events were during takeoff. One of them happened at gear retraction (see T &T September 2010), and the above event was my only engine failure, a high-speed abort. And it’s always the time compression that amazes me. I’ve had a handful of events, like this one, that were intense enough to cause the linear time anomaly. If you’ve never experi- enced it, you will. Can it be explained away as simply an adrenaline and dopamine-induced change in perception?
 %        !"!$

Reasons to Stop: Fire, failure, stall, controllability, wind shear
The weight and balance and takeoff performance software used by my part 121 carrier provided minimum runway lengths and V-speeds to define the accelerate-stop/go and balanced field length parameters. The program I use in the Citation instead provides a maximum takeoff weight and V- speeds for a user-specified runway to meet the balanced field length definition—any weight below that calculated weight gives you runway to spare. Also, an engine failure is not the only reason to reject a takeoff. The commonly accepted reasons to abort include fire, failure, stall, controllability and wind shear. That is ANY fire (cockpit, cabin, cargo, or engine), engine failure, wing or compressor stall, aircraft controllability concerns and wind shear or micro-burst.
Other Bad Things
Up to a predetermined speed early in the takeoff, we are trained to watch for any reasons to stop, not for reasons to go. In high-performance twins and most jets, the first
May 2023 / TWIN & TURBINE • 27