Aero-Tips!

A good pilot is always learning -- how many times have you heard this old standard throughout your flying career? There is no truer statement in all of flying (well, with the possible exception of "there are no old, bold pilots.")

Aero-News has called upon the expertise of Thomas P. Turner, master CFI and all-around-good-guy, to bring our readers -- and us -- daily tips to improve our skills as aviators. Some of them, you may have heard before... but for each of us, there will also be something we might never have considered before, or something that didn't "stick" the way it should have the first time we memorized it for the practical test.

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Aero-Tips 11.15.06

The single-engine service ceiling of a multiengine airplane is the density altitude at which the airplane, at maximum weight in a clean configuration (gear up, flaps up, inoperative engine's cowl flaps closed and propeller feathered), is capable of climbing at 50 feet per minute. The published single-engine service ceiling (SESC) for the most popular light twins is usually in the 3500-5000 foot range... density altitude. Turbocharging usually raises the SESC to 12,000-15,000 feet.

Why should a multiengine pilot know the SESC of the airplane he or she is flying?

Climbing up

Lose an engine on takeoff and you'll need to climb to a safe altitude before you can maneuver to land. If the density altitude at the departure airport is near the airplane's SESC and the airplane is near maximum takeoff weight, it may not be possible to make this safe climb to a maneuvering height. Or if there are significant obstacles, the plane may be able to begin the climb but won't have the power to outclimb the obstacle. The pilot of a multiengine airplane would have no choice but to reduce power on both engines and land nearly straight ahead if an engine quit under these conditions. Attempting to climb out runs a very real risk of colliding with terrain, or the temptation to attempt a turn at too slow a speed and lose control of the aircraft.

Drifting down

Similarly, if an engine quits above SESC and the pilot flies at "blue line" speed (maximum single-engine performance, Vyse) the airplane will descend at the lowest rate of descent until it reaches approximately SESC. Overflying mountains? Consider that losing an engine in a twin may not present very many more options that it would in a single-engine airplane…you should still plan your route to provide an "out" to lower terrain or an off-airport landing should an engine quit and the terrain below you is above your SESC. Even a turbocharged twin could drift down to ground level over the Rocky Mountains.

Weight

Airplane weight makes a big difference in single-engine performance, so it will raise the SESC. Whenever possible, fly a multiengine airplane at the lowest safe weight (that provides sufficient fuel and reserves) to improve your SESC and single-engine climb rate.

Aero-tip of the day: Look at the density altitude, and consciously consider the relationship of takeoff and terrain density altitude to your airplane's single-engine service ceiling.

FMI: Aero-Tips