September 1, 2002
By Bruce Landsberg
How much will she carry? It is a question every pilot has asked or been asked in preparation for flight. For designers, the load equation is complex: engine power output, shape and size of the wing, quantity and placement of fuel tanks, location of baggage compartments, and much more. For the airlines and commercial operators we're talking payload. Not enough load—no pay. But for most pilots, the decisions are relatively simple.
There are two concepts that must be understood with certainty lest gravity get the upper hand: maximum takeoff weight and center-of-gravity limits. Some pilots have flirted with exceeding them and have been successful. Many others have made the wrong kind of headlines.
In August 2001 the media coverage surrounding the loss of the rock star Aaliyah Haughton was intense. The Cessna 402 on which she was a passenger crashed on takeoff in the Bahamas, killing nine people. The aircraft was overloaded by hundreds of pounds, and it was reported that one charter company refused the trip when it heard that the load was way beyond the capability of its aircraft. That accident was well chronicled and was so far beyond the limits of what most pilots would consider reasonable that it's more instructive to look at something a little less extreme.
A Piper Warrior pilot announced his departure on Runway 11, which was 2,801 feet long. Another pilot, who was entering the airport area from the northwest, announced his intentions of performing touch and goes on Runway 29. The second pilot observed the Warrior take off and roll into a 45-degree-bank turn. He estimated the altitude of the Warrior to be 200 to 300 feet agl before he lost sight of it.
Another witness reported, "The plane took off heading southeast, with the wind. When it got about as far as 12th Street, the tail dropped way down. It was almost straight up and down. The pilot powered up the [engine] just before the line of trees, [the airplane] just barely made it over them. Just before it dropped below the tree line and out of sight, we saw it bank [to the] right." The aircraft struck trees and burned. There were no survivors among the three occupants.
The pilot had an estimated 300 hours flight time, had flown about 12 hours in the preceding 90 days, and had a current flight review. The pilot weighed in at 230 pounds, the front seat passenger weighed 240, and the rear seat passenger was 134. An estimated 30 pounds of baggage and a full load of fuel at 288 pounds completed the manifest. The aircraft's approximate weight was determined to be 2,514 pounds at the beginning of the flight, but the PA-28-161's certificated maximum gross weight is 2,325 pounds. The airplane was carrying 189 pounds too much.
Now add a few additional factors: The wind was from the northwest at 11 knots but the pilot departed to the southeast, and the outside temperature was 31 degrees Celsius, or about 90 degrees Fahrenheit. Under these conditions, the climb would be anything but sprightly. The NTSB found no problems with the aircraft and the engine, but it did cite the pilot for operating the aircraft overweight. It's worth noting that stall speed increases as weight increases, but once outside the design envelope there are no tables or graphs to tell you how bad it's going to be.
In another accident, a Piper Saratoga struck trees and subsequently the ground shortly after takeoff. The pilot was fatally injured, three passengers received serious injuries, and one passenger received minor injuries. According to witnesses at the airport, the airplane used about three-quarters of the 5,002-foot runway on the takeoff roll, and just before liftoff they heard the engine "misfire." The airplane did not seem to climb, and it was observed to porpoise just above the trees. There were two or three oscillations and then the aircraft disappeared. The impact point was about 1.1 miles from the end of the runway.
The pilot held a private certificate with airplane single-engine land, multiengine land, and instrument ratings, and he reported 610 hours on his last medical examination. The airplane's weight and balance records listed the basic empty weight at 2,362 pounds and maximum gross weight at 3,600 pounds. Adding the pilot and four passengers' combined weight of 901 pounds, an estimated 25 pounds of baggage, and fuel weight of 564 pounds, the airplane's total weight at takeoff was 3,852 pounds. That's 252 pounds too much.
Winds were light and the temperature was in the mid-80s F—again compromising what little, if any, climb performance might have been available under cooler temperatures.
The engine was examined but was badly damaged in the impact. The "misfiring," something frequently reported by witnesses according to the NTSB, could not be confirmed or denied, but propeller slash marks on pine trees at the crash site indicated that the engine was developing power.
A medical report on the pilot found that Hydrocodone, a prescription narcotic painkiller, was in blood and liver samples. Dihydrocodeine, a prescription narcotic painkiller used to control moderate to severe pain, and acetaminophen, a common painkiller often known as Tylenol, were also detected in the pilot's blood. The probable cause was overload of the aircraft with a factor of unapproved medication. Could that have clouded the pilot's thinking or slowed his reaction to reject the takeoff?
This really is not intended as a manufacturer-bashing exercise, but the next aircraft was also a Piper, a new PA-46-350P Malibu Mirage. Piper is represented in many accidents through no fault of its own, guilty only of building one of the most popular lines of airplanes.
The last example begins to approach the Aaliyah accident for incredibility. The male passenger reportedly arranged with the pilot the prior evening to be the sole passenger for a trip up the East Coast to New England with a fuel stop on the way. However, he arrived the next morning with a second passenger and a large dog. The airplane was topped off with 14.7 gallons of avgas before departure. That was an extra 88 pounds they did not need under the circumstances.
Several witnesses located at the departure end of Runway 5 observed the Mirage approximately 10 feet above the ground in a nose-high attitude and not climbing. The right wing was observed to dip 45 degrees, then level off. Seconds later, the left wing dipped 45 degrees, and again, the airplane leveled off. Several other witnesses saw the airplane narrowly clear the 6-foot fence off the departure end of Runway 5. The engine was reported to be running smoothly. The airplane struck a utility pole, the roof of a bus stop, and a brick wall approximately 150 feet beyond the utility pole. There were no survivors. The NTSB could find no pre-impact malfunctions with the aircraft.
The pilot held a commercial certificate with single-, multiengine, and instrument ratings. He had approximately 6,000 total flight hours with 80 in a PA-46-350P and had completed ground and flight training for the Mirage.
At the time of the accident, Runway 5 was in use with an upslope of 1.2 degrees and a length of 3,900 feet. The wind was nearly calm and Runway 23 was available, which would have had a downslope and no obstacles.
According to the Mirage's information manual, the maximum takeoff weight is 4,318 pounds with a useful load of 1,201.7 pounds. This airplane was loaded with a pilot weighing 205 pounds, one passenger weighing 200 pounds, another passenger weighing 122 pounds, a dog weighing 100 pounds, three baskets of fruit weighing 75 pounds, 193 pounds of miscellaneous items, and full fuel (120 gallons) at 720 pounds. There is no record of the pilot completing weight and balance computations prior to takeoff. That doesn't mean that he didn't do them, but either way, the results speak for themselves. The Mirage was estimated to be more than 400 pounds over the maximum takeoff weight.
It's worth noting that all these pilots had significant flying experience, and it's a safe bet they had probably overloaded their aircraft before. Will it fly safely 10 pounds overweight? Likely. How about 40 pounds overweight? Possibly. How about 150 pounds? It may fly under certain circumstances but not as the manufacturer intended. Do your passengers know that they are participating in a test flight? The similarities among these accidents include a significant overload, an aircraft not flying well and ultimately stalling or striking an obstacle, followed by fire and fatalities. That is good motivation to ensure a successful takeoff.
With full fuel, little airspeed, altitute, or climb ability, it should be obvious that cheating on weight and balance carries some extreme penalties.
Aircraft Power and Fuel,
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