Tuesday, May 10, 2011
Takeoff Mistakes: The Critical Minute
It all has to come together in the first 60 seconds, or the rest of the flight may not matter
Willett died in the first minute of flight out of Lakeland, Fla., back in the mid-’80s. He was loaded with ferry fuel for a trip to South America, and shortly after takeoff, the airplane was seen to pitch up, stall and nose straight in. Willett was probably killed on impact. We’ll never know for sure what happened to him, but it’s apparent something went very wrong during that critical first minute.
The initial 60 seconds after you push the throttle(s) up remain the riskiest part of any flight. Some pilots regard the landing as the acid test, but barring pilot error, the airplane has already proven its willingness to fly by that time. Each takeoff is a new test.
Instructors have been warning for years that many takeoff accidents are born during the preflight, long before the pilot even starts the engine. Though most pilots will agree that checklists can shortstop omissions in the cockpit, too many of us fail to use them during the preflight. You’ll notice I said “us.” Many aviators, this one included, have started engines with chocks still in place, or with one or more tiedown ropes still attached. Another common problem is pilots leaving pitot-tube or engine-intake covers in place, again easily avoided with a takeoff checklist.
In one instance, the pilot of an A36 Bonanza dragged a large piece of concrete to the run-up area, and actually initiated takeoff with the huge concrete block still attached. To the surprise of several witnesses, the airplane actually managed to stagger into the air before the huge block won the tug of war, pulled the tail down, and slammed the airplane back to the runway, collapsing the gear and totaling the airplane. The pilot was lucky to walk away.
An appropriate preflight is critical on all aircraft, but some owner/pilots who keep their aircraft in private hangars have a natural advantage. Not much can change between flights on hangared, private aircraft, whereas aircraft operated by a variety of rental pilots and stored outside can experience more adverse changes, and many of those won’t be noted on the squawk sheet.
Fly The Airplane First
Too many takeoff accidents don’t have to happen. Some of the most common of these devolve from a cabin or baggage door popping, a storm window coming unlatched (though most of those simply seal up tight from the inside), or an oil door suddenly arcing full open as the aircraft lifts off. The change in angle of attack and airflow often precipitates anything loose to open.
Rotation speed is one of the busiest times anyway, and the last thing you need when you’re initiating liftoff is an emergency that really isn’t one. Most aircraft manifest little or no aerodynamic reaction to an open door, but the noise and rush of air can deceive an unwary pilot into believing he has a real problem. The cardinal rule is to ALWAYS continue to fly the airplane first, and troubleshoot the problem second.
Sixty seconds without a critical failure is no guarantee of success on the flight, but if you’re smart enough to leave everything alone, it should provide a good hedge against problems. Gear and flap retraction might seem obvious exceptions, and most of the time, that’s true. Most of the time. Some manufacturers suggest you lose virtually nothing in climb by leaving takeoff flaps deployed, and there even are circumstances when quick gear retraction is inadvisable.
I was flying out of a near-7,000-foot-tall mountain strip recently on a gusty day, and someone on the Unicom alluded to possible wind shear. Forewarned, I didn’t immediately retract my Mooney’s landing gear when I had positive rate. Good thing. Climbing through 100 feet AGL, airspeed dropped by 20 knots, and the airplane began to sink back toward the runway. Fortunately, we didn’t descend all the way to the asphalt, but if we had, at least the wheels would still have been under me.
I’ve always followed the advice of an old instructor who once preached poetically, “When you push the throttles forward, don’t do nuthin’ but fly till there’s plenty of sky.” After you put the wheels to bed and streamline the underwing (assuming no wind shear), leave the power running at maximum for at least the next three to five minutes, and fuel pumps on if they’re required for takeoff. I leave pumps on for at least the first 3,000 feet. If the engine-driven pump fails and only the electric is available to maintain power, I’d rather discover that fact at 3,000 feet than in the first minute when a temporary lapse of power could be more critical.
On that score, it’s important to assure that the pump actually works well before you begin takeoff. On those airplanes that demand pumps for engine start, you have an obvious clue if the pump fails, but guarantee that it still works as you taxi out. On other airplanes, it may be more difficult to determine pump health.
One method of checking operation is looking for a spike in fuel pressure, though that’s often not definitive on airplanes with low pressure systems. A second method is to watch for an ammeter drop, though again, most pumps draw so little power, you may not see much change. Finally, you can simply listen for the sound of the pump, preferably at idle power.
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Labels: Accident Statistics, Decision Making, Emergency Situations, Features, Flight Planning, Flight Training, Flying Skills, Pilot Safety