"Winter's almost over and the summer's comin'/The days are gettin' long." That line, from "Fishin' in the Dark" by The Nitty Gritty Dirt Band, leaves out two things: The days are also going to get hot, and the other thing that will be "gettin' long" will be our takeoff and landing distances, thanks to high temperatures and higher density altitudes. These are conditions that affect every airplane, single-engine or multi, piston engine or jet. If you need to operate from a high-elevation airport while carrying a heavier-than-normal payload, takeoff and landing performance suffer even more.
What can be done to maximize takeoff safety? Most of us in general aviation will fly only single-engine airplanes - they are the most readily available and the least expensive to fly. But many will be fortunate enough to pursue a multiengine rating. Flying a multiengine airplane is not hard. The training is of fairly short duration and it is not, in and of itself, difficult. But it does bring new terms and practices, all of which are designed to emphasize safety. In fact, multiengine training consists mostly of learning to handle single-engine emergencies.
Essential to multiengine training is learning to prepare for and handle an engine failure during the takeoff roll. It is a practice of calculating the aircraft accelerate-stop distance, a number that is specific for the given temperature, airport elevation, and aircraft weight. This concept also can be applied to single-engine aircraft, for the same reason - to improve takeoff safety.
If you lose the engine in a single-engine airplane during the takeoff roll or shortly after rotation, there is very little decision-making to be done. If the engine fails on the ground, you will stop. If the engine quits right after rotation, you will land. Pretty simple logic. You hope that you will land on the runway, but whether the engine quits on or off the ground, you are going to have two concerns: stopping safely and stopping on the runway.
An engine failure on takeoff in a multiengine airplane, however, is a much more complex series of events. In nearly every piston-powered airplane, failure of either engine on the runway will be cause to abort the takeoff and come to a stop on the remaining runway. The operating engine is not going to have the power necessary to get the plane airborne and clear of obstacles, especially on a hot summer day at anything approaching maximum gross weight. Therefore, standard operating procedure in the multiengine piston environment is to abort the takeoff - regardless of speed - if an engine fails during the takeoff roll.
But multiengine pilots still calculate their accelerate-stop distance. The accelerate-stop distance is defined as the distance it will take to accelerate to liftoff speed, experience the failure of one engine, and still brake to a complete stop on the remaining runway. During the heat of the summer, with higher density altitudes and temperatures, it is possible that the total accelerate-stop distance will exceed the length of the available runway. If this is the case, the choices are to attempt to take off anyway and hope that an engine does not quit; reduce the payload; or delay the flight until the temperature cools enough to improve performance.
Sometimes, airlines find themselves unable to service certain airports because the takeoff data indicate that such operations would be dangerous. Airlines operate using a balanced field. For a field to be balanced, the total accelerate stop-distance - considered the total takeoff distance - equals the available runway length. On a long runway, the available runway will exceed the runway required; the runway is not balanced, but that's OK because it's longer than necessary. For short runways, however, an unbalanced field usually renders the runway unusable, because the runway required exceeds the runway available. This is a recipe for disaster.
As the pilot of a single-engine plane, you are not required to calculate such distances. Technically, they do not even exist. Academically, however, calculating some type of accelerate-stop data may open your eyes as well as ignite some interesting hangar conversations.
It's possible to dig a little deeper into your anticipated performance using the charts in the pilot's operating handbook (POH) for your airplane. While the federal aviation regulations require you to calculate your takeoff and landing distances before any flight, most of us don't - unless we feel that circumstances dictate. But that might be worth reconsidering.
Performance data for all aircraft - whether piston, turboprop, or jet - have certain things in common. All must take into account the environment and existing conditions. That includes runway slope (or gradient), runway surface, runway elevation, takeoff weight, ambient temperature, and winds. "Hot and high" conditions - high temperatures and field elevations - cause extra concern because they combine to reduce aircraft performance and increase takeoff distances.
For instance, take an airport at sea level with a runway that is 2,900 feet long. In the summertime, even with a pressure altitude of sea level, a fully loaded Cessna 172 Skyhawk (2,400 pounds) on a 30-degree Celsius/90-degree Fahrenheit day will require approximately 995 feet of runway to become airborne; it will need 1,810 total feet to clear the FAA's 50-foot obstacle at the end of the runway. The same airplane, landing at 2,400 pounds, will need 570 feet of runway to roll to a stop after touching down. If coming over a 50-foot tree, the landing requires a total of 1,325 feet. Just using the ground-roll numbers alone, 995 plus 570 equals 1,565 total feet of asphalt. In this example, there is plenty of room to accelerate to takeoff speed, experience an engine failure, and roll to a stop on the remaining runway.
If, however, the airplane has become airborne, watch out. Assume that it climbs to 50 feet before the engine quits. Now, we are looking at 1,810 feet of takeoff distance plus 1,325 feet of landing distance for a total of 3,135 feet of total runway used - and, in this case, exceeded.
The situation is actually worse than indicated, because after losing the engine at 50 feet, the airplane is going to glide while slowing to a landing speed. It's probably also going to continue to climb for a short period before the pilot can react. If in the heat of the moment you land with the flaps up (the normal takeoff configuration) you will be landing faster and using even more runway surface to stop. Remember, the accuracy of the landing data depend on the airplane's being established at a certain speed when overflying that 50-foot tree. In this case, you are probably faster than that speed, so that actual landing distance will be greater than just the sum of the takeoff and landing numbers.
Piper aircraft performance tables do not provide separate ground roll numbers. They just provide the total departure distance over the 50-foot obstacle, and the graphs are a little more cumbersome to use. Using a generic set of Piper Warrior performance charts on the same day with another fully loaded airplane, the takeoff distance would be 2,100 feet. The total landing distance would be about 1,250 feet, for a combined total of 3,250 feet�a little worse than the 172's showing. And because you don't have separate ground roll numbers, you are actually less informed.
These examples make a clear case for pilots to climb at the best rate of climb airspeed (VY) to a safe altitude after takeoff, for two reasons. First, for many aircraft this airspeed is very close to the approach speed, simplifying the transition from takeoff to landing if the engine quits at 50 feet. Second, you will gain altitude - and options - as quickly as possible, buying you more choices if the engine fails at a higher altitude.
Another factor for the single-engine pilot to consider is a grass runway. For both the Warrior and the Skyhawk, the penalty is an increase in ground-roll distance of more than 30 percent. Move the same 2,900-foot runway and 2,400-pound airplane to an elevation of 2,000 feet above sea level, and the performance deteriorates even more.
There are flight instructors who advocate padding the performance numbers by 50 percent to take into account all the variables that can affect performance. As you are no doubt aware, older airplanes, like older cars, do not always perform as well as newer ones. If you are flying an older one, it's worth remembering that the POH data was acquired in a new plane with a new engine, new prop, new tires, and new brakes - not the worn, scuffed, and tired versions on the old rental. Also, the test pilots were able to practice and perfect the techniques for takeoffs and landings before logging their data. When the time comes that you most need perfect technique and performance, you probably won't have it.
Airlines and major charter or corporate operations provide charts of single-engine takeoff data for their various aircraft. A quick look at the charts will determine for the pilot whether or not a safe takeoff can be guaranteed. In Mexico City, for example, the airport elevation is more than 7,000 feet msl. The jet that I fly is usually limited in its takeoff weight on hot summer days, because even though the runway is more than 10,000 feet long, the runway required to ensure a single-engine climb would exceed that when temperatures are high.
Single-engine pilots are not required to calculate accelerate-stop numbers, and airline-quality charts are not available. But you need to know when you start that takeoff roll - whether flying a single engine or a multi - that you can stop on the runway remaining should it become necessary. Use the data you have available. You could lose a lot more than just the engine.
Chip Wright is a 5,500-hour airline transport pilot and a captain for Comair. He is a multiengine and instrument flight instructor. In his spare time, he is building a Vans RV-8 kitplane.
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