May 1, 2012
By Peter A. Bedell
An engine fire at V1? Your best strategy may well be pitching up to the command bars, taking off, then discharging the fire bottle in the air as you make your way back for an emergency landing. Although tempting, a high-speed aborted takeoff is usually a dangerous way of dealing with many emergencies.
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Unlike in light airplanes, aborting a takeoff in a heavy jet can be a big deal. The amount of energy a 200,000-pound aircraft contains when moving along a runway at 150 knots is immense and bringing that mass to a stop exposes its occupants to a number of risks from blown tires, brake fires, and a very real threat of running off the runway. The latter, of course, can easily lead to crew and passenger injuries or deaths—as well as serious damage to the airplane, depending on the terrain off the end of the runway. In many cases, once you’ve reached a certain speed during the takeoff roll in a large turbine airplane, it’s time to shift your thinking to being go-oriented—even if there’s a serious threat to the airplane from something like an engine fire.
Pilots of light airplanes may think that going flying with an engine on fire is insane, but when you consider that most jets have the equipment to isolate and extinguish an engine fire, the rationale for continuing the takeoff begins to make sense. After all, a trip off the end of the runway is a sure bet to make the evening news.
For many airplane types there typically is an airspeed at which aborting for yellow caution lights typically should not be attempted—the transition point to becoming go-oriented, if you will. (Aborting for a red master warning light, if such a decision is made, is typically made up to the takeoff decision speed or V1, depending on the airplane type.) In the Jetstream turboprop I used to fly, that transition speed is 70 knots. If a red warning or yellow caution light illuminated before reaching 70 knots, we’d abort the takeoff and look into the problem on the ground. Above 70 knots, we’d ignore the yellow cautions and continue the takeoff, evaluating the issue in the air. In the Boeing 737 I fly now, 100 knots is the magic number.
Let’s say you’re accelerating through 120 knots on takeoff in a fully loaded 737-800 and a light illuminates indicating that one of the over-wing emergency exit doors is open. Do you imagine the hapless passengers squirming near an open door—with a 138-mph breeze and the deafening roar of a jet engine bombarding them—and abort? My airline tested many pilots with this very scenario in the simulator to see what they would do. For a few, the thought of the terrified passengers got the better of them and they aborted the takeoff. Bad idea. The over-wing emergency exit door light is part of the master caution system and is therefore a yellow light, for which we do not abort when faster than 100 knots. And, Boeing designed those doors to essentially lock themselves during the takeoff roll, basically making it impossible for them to open on takeoff. An indication of an open door at high speeds likely would be a false indication.
If you’re a bit slow on the decision, you may have just put another 500 feet of runway behind you.
Reaction times are key in a potential abort. This is no time to be on the fence about what to do. The time to recognize a threat, decide what to do, and take action consumes a minimum of 0.75 seconds, according to researchers. If you’re a bit slow on the decision, you may have just put another 500 feet of runway behind you. That minimum reaction time is built into takeoff planning charts to derive V speeds, required flap settings for the runway in use, and reduced-thrust takeoff capability. Any additional time you take is throwing your abort option out the window. If you whittle away a few seconds deciding what to do as you are still accelerating, you may be aborting beyond V1, which assures that you won’t get the beast stopped in the remaining runway—and if you survive the adventure, you’d better polish up your résumé.
Pilots must condition themselves to transition to the go-oriented mentality. Sometimes a physical cue can help. When reaching V1, pilots remove their hand from the power levers as a reminder that it’s not a good idea to pull those back after V1. For the 70-knot transition in the Jetstream, I’d keep my left hand on the tiller until 70 knots. After that, I’d move it to the yoke. This cued me to think, “If my hand’s on the yoke, the only thing I’m aborting for is a red warning light.” You can make up your own cue for the airplane you fly. When flying light twins, I use a similar trick. My right hand is on the throttles until I reach for the gear lever. After the gear is selected up, my right hand goes to the yoke as a reminder it’s time to fly rather than think about putting it back on the ground.
Operations at lighter weights off long, sea-level runways give pilots more leeway and runway room to make an abort decision. But the hot, high, and heavy takeoffs make these speeds and decisions critical. In these situations, your best decision may be to go flying.
Pete Bedell is a first officer for a major airline and holds type ratings in BAe Jetstream 41, Canadair RJ, and Boeing 737 aircraft.
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