Mention the word "abort" to a pilot, and you'll immediately summon visions of every pilot's nightmare— an engine failure on takeoff. The airlines have hard and fast rules for handling that problem; general aviation should have the same rules, but it usually doesn't.
Airlines deal with balanced field lengths, ref speeds and other constraints that can practically make any decision for them. Airline crews drill every six months during recurrency checks on every possible emergency, using sophisticated simulators to protect them from harm.
Personal airplanes operate with a different set of rules. All airliners fly behind at least two engines, while the vast majority of general-aviation machines are singles. That obviously means any malfunction should demand an abort unless that's absolutely impossible. Even if we do fly twins, we're sometimes operating from short runways in adverse conditions, situations where deciding to go or stop can be extremely difficult.
Or not. Sometimes, the decision to abort isn't a matter of choice. I was bringing back a Cessna 421 from Subic Bay, Philippines, to Oakland, Calif., 10 years ago. The airplane was an old friend. I had delivered it to Subic only three years before, but the diminishing supply of avgas in Indonesia and the Far East convinced the owners to trade up to a King Air.
The legs to Guam, USA, and on to Majuro, Marshall Islands, had gone without too much difficulty. I had overnighted in Majuro before the long, 2,000 nm leg up to Honolulu.
The next morning, I was sitting in the airplane, ready to fly, at 7 a.m. Majuro's only runway slices along a rare, straight section of the narrow island. The ring atoll is only about a quarter mile from lagoon to Pacific, and runway 7/25 has beach on both sides, no more than 100 yards from the centerline. If you lose directional control left or right, there's a good chance you're about to get the airplane wet.
I lined up on runway 7, pushed up the power and watched the needles rise to the redlines. I released the brakes, and the 421 began to roll down the 7,900-foot concrete strip with the acceleration of an ice-cream truck. Speed with the heavy overload of 350 gallons ferry fuel eventually managed to reach liftoff.
I was reaching for the gear handle when the left engine suddenly lost power. The airplane pulled hard left, and the port wing dropped toward the sand. I chopped the right throttle, managed to level the wings, slammed the 421 back onto the concrete and stood on the brakes as the runway-end fence loomed straight ahead.
The twin Cessna finally screeched to a stop, with two flat-spotted tires and burned-out brakes trailing smoke. I was able to turn off at the end onto the west ramp, but unable to taxi as the left engine was unresponsive and the brakes were pretty well fried.
The left throttle linkage had apparently snapped immediately after takeoff, probably a result of three years of corrosion in the salty, humid air of the Philippines. I don't usually deal in what ifs, but I couldn't help speculating what would have happened had the linkage waited another 10 seconds to break. By that time, I would have been out over the water. At 1,400 pounds over gross, the 421 would have stood no chance of flying on the remaining engine alone.
In this case, the abort was my only choice, but some instances may not seem so clear cut. Back in the 20th century, Cessna used to build a centerline thrust twin called the Skymaster. The design was intended to eliminate the minimum control speed (Vmc) associated with asymmetric thrust and improve the chances of surviving an engine failure.
There was one problem, however. The rear prop was a pusher mounted on the aft fuselage, out of sight and often out of mind. That meant some pilots would try to save a little fuel by taxiing on the front engine only.
Most pilots were smart enough to abort when full throttles didn't produce normal takeoff power, but incredible as it may seem, some Skymaster aviators would forget to start the aft engine—or to restart it if it had idled out—and initiate takeoff with only the front mill running.
It might seem impossible not to notice that the airplane wasn't accelerating properly, but several pilots still blundered off the end of runways wondering why their shiny Skymaster wasn't accelerating very well. Cessna solved the problem by placing the world's largest alternator-out light on the panel to indicate that one or both alternators weren't on line. Cessna also modified the takeoff checklist to require leading takeoff power with the rear (right) throttle first. If there was no response, fill in the blanks.
The more typical problem of determining when to abort a departure is usually a fairly simple decision. In a single, ANY anomaly that affects the airplane's ability to lift off and climb or distracts the pilot should be cause for retarding the power and aborting the takeoff, assuming there's adequate runway remaining. In addition to the obvious loss of partial engine power, that includes an electric fuel pump that's inop, a door or window that pops open, flaps that refuse to retract or extend properly, a seat that won't adjust, an oil-filler cap that's not properly tightened, the odor of electrical smoke in the cockpit.
This isn't to suggest that many of these problems can't be dealt with in flight. The difficulty is that takeoffs are perhaps the most demanding segment of flight and require your undivided attention. If you have the option of dealing with these difficulties on the ground, you'll be less liable to become distracted and perhaps fly the airplane into the ground.
Unfortunately, not all aborts are associated with takeoff, though problems during departure may be the most critical. Perhaps the more difficult decision is related to aborting a flight already in progress and performing a precautionary landing. This could be a result of extremely adverse weather, poor fuel planning or a number of other circumstances. If there's an airport nearby, the choice is simpler, as there's little chance of damaging the airplane.
The problem arises when you're forced to consider an off-airport landing with a perfectly good airplane under you. I made one of those in Alaska 30 years ago because of a stupid weather call. I had plenty of fuel, the new Mooney's engine was running perfectly, but the ceiling/visibility was rapidly deteriorating toward zero/zero. At the time, I was doing what Alaskan pilots do all too often, scud running. The scud simply got lower than I expected.
Fortunately, there was a convenient straight stretch of highway nearby and no traffic in sight. Landing on a highway is legal in Alaska (provided you don't hit anything), a benefit not shared in most states. I taxied the airplane to a wide spot, shut down, tailed it as far off the road as I could, and settled in to wait out the weather. An Alaska Highway Patrol officer stopped to check on me, hung around and talked airplanes, then went on his way, with a smile and a, "Be careful."
But let's say you're basically out of options, you're faced with an off-airport landing, and there's a good chance you may damage the airplane in the process. That's a tougher call. Do you continue in inclement weather and take your chances, or do you do the best you can with whatever's below? Unfortunately, too many pilots choose to continue on the premise that things are bound to get better. Bad idea. In keeping with Murphy's Law, things are perhaps more likely to get worse.
Another typical scenario is the pilot who runs his fuel reserves too tight because of poor planning or unexpected winds. (The rule is: Any attempt to stretch fuel is guaranteed to result in stronger headwinds.) Then, he must decide whether to make a controlled precautionary landing at a preselected site while power is still available or be forced into accepting a power-off landing at whatever semi-flat location he can reach within gliding distance.
A single-engine instrument readout shouldn't necessarily be cause to consider a precautionary landing. A high or low cylinder-head temperature, unsupported by any other abnormal instrument indication, may not be enough to justify aborting a flight.
The bad news about a precautionary landing is that you may damage the airplane or perhaps even suffer some injuries. That tends to discourage some pilots from aborting a flight, simply because they'll have to answer questions later and perhaps admit they made a mistake. Pilots are a proud bunch, and serious mistakes that might result in a bent airplane or an FAR violation aren't part of the profile.
The good news is that landing before the situation becomes too critical may provide the benefit of time. If the weather is deteriorating rapidly and you need to put the airplane on the ground now or risk hitting an unseen mountain, you may have few options. If a lack of fuel dictates a precautionary landing, however, you may have the option of examining several possible emergency sites before choosing one. You'll also have the relative luxury of preparing the cockpit for the touchdown; securing loose items, making certain everyone is strapped in firmly with seat belts and shoulder harnesses fastened, popping the door in the flare, etc.
Dozens of books exist on how to land off airport, and we won't attempt to summarize them here. What happens after you make the decision to abort a flight depends upon dozens of factors, not all of which you can control.
If you do decide to abort any portion of a flight, you've probably made the right decision. Better to err on the side of safety than continue and make a bad situation worse.