Say When

1] When should you power-up a cold engine for takeoff?
Depends on who you ask. I know of some pilots who feel you can run up any time the engine will take the power without stumbling; then, take the runway and leave town. On the other hand, I have several friends in the engine- overhaul business who feel you shouldn't even consider doing the run-up until the oil temp reaches 100 degrees F. Piston engines are made of a variety of metals, and all those materials must be up to temperature before you apply major power.

Fortunately, most modern airplanes are fitted with accurate digital engine analyzers that allow reading the temperature to the nearest degree. Those antique peanut gauges are rarely accurate enough to suggest when you're at 100 degrees.

2] When should you retract the gear after takeoff?
You'll hear a variety of opinions on this question, and it may seem hard to arrive at a logical answer. The premise isn't to retract the wheels until you know you won't be able to use them for an aborted landing on the remaining runway.

You can discard a few answers out of hand, however. One rule is to always wait until you're 500 feet AGL. Not such a bad idea, but on some airplanes with high drag signatures when gear is down, that could compromise climb performance at a critical moment when you need max altitude in minimum time.

Another old saw suggests, "Retract the gear when you can no longer see runway over the nose." Pretty dumb. How tall are you? Is your seat adjusted to the highest setting or the lowest or are you sitting on a cushion? Are you climbing at Vx, Vy or a cruise climb speed, all of which will demand different nose attitudes and provide a different slant-range view straight ahead? What's the slope of your top cowling, level, downhill or uphill? Answer all those questions, and you can see the "runway ahead" directive could vary by several thousand feet on the same day with the same load into the same wind.

There's a logical solution that doesn't demand much calculation, however. Look at your POH, and examine the takeoff and landing distance over a 50-foot obstacle. According to my Mooney's handbook, I need 1,384 feet for takeoff and climb to 50 feet and 1,786 feet for landing from the same height on a standard day at gross and sea level. Add, say, five seconds at 80 knots to recognize a failure (135 fps x 5), and you'll need to increase that total distance by about 700 feet. Assuming you have lightning reflexes, your brakes are brand new and you do everything else perfectly, you'd need roughly 3,900 feet of runway to land and stop. More realistically, considering that you probably didn't depart from the first few feet of runway, figure 4,000 feet to depart, climb to 50 feet, lose the engine and get your airplane back on the ground safely with nothing more than burned rubber. (Yeah, right.)

That means if the runway length is 4,000 feet or less, it barely matters when you retract the wheels, as you won't be able to stop in less space anyway. If you're flying from a longer runway, you'll have space to reposition the gear to down. For that reason, I retract the gear at about 100 feet, regardless of runway length. (Yes, I'm aware there's nearly always a difference in flap configuration between takeoff and landing, but this is a general rule.)

3] When should you reduce power after takeoff if you're flying behind an engine that uses a METO (maximum except takeoff) power setting?
Some engines are approved for max continuous operation all the way to level-off. Others may have three- or five-minute limitations, usually requiring a reduction in rpm.

Too often, owners of airplanes that have big fuel burns on takeoff are eager to get the power back as soon as the wheels are in the wells to reduce fuel flow and also to staunch the financial bleeding.

Bad idea. Reducing power too soon not only costs performance and minimizes the safety pad of altitude, it may result in higher cylinder temperatures---never a good idea. The engine will run cooler at full power and full rich than at a lower setting.

If you have a three- or five-minute limitation on max power, use it all. On most singles, five minutes at full power will generate at least 3,000 feet of altitude, a good pad in case you need to make some hard decisions. Reducing power too soon could wind up being the ultimate false economy.

4] When should you reduce power to cruise and begin the level-off?
Some pilots believe there's such a thing as a cruise "step," an imaginary aerodynamic condition that allows any airplane to fly faster on the same power at the same weight and altitude. Sorry, no such magical condition exists.

There's a legitimate technique for reaching optimum cruise speed quicker, but it has nothing to do with a step. Climb 100 feet or so above your planned cruising altitude, leaving the power against the stop (or at max climb); then, push over and descend to cruise height. Level the airplane and wait until airspeed peaks before VERY slowly reducing to cruise power.

Leveling a hundred feet high and descending back down to your cruising altitude will deliver slightly bigger numbers on your ASI---but only temporarily. Eventually, the final cruise indication will stabilize at exactly the same speed as if you leveled at the optimum altitude initially. There will be a very small short-term benefit of the dive-down technique, but it won't result in any permanent speed increase.

If you're like so many of the rest of us who fly four-seaters with the rear seats empty, one way you CAN increase your cruise performance slightly is to slide the front seats all the way back to generate a more aft CG during cruise and reduce the down force on the tail. That may generate a knot or two of extra cruise on most general aviation singles.

5] When should you close the cowl flaps for cruise?
Some aircraft checklists suggest closing the cowl flaps as the last item on the cruise checklist. In fact, it should be the first item. Some manufacturers forego cowl flaps altogether to keep things simple for pilots; others install the cooling doors primarily to help control engine temperature during climb and for extreme hot weather operation. Aircraft cowlings are nearly always an aerodynamic compromise between the conflicting demands of climb and cruise. The late Roy LoPresti once told me he designed his cowlings almost exclusively for cruise---then, he mounted the largest cowl flaps he could to keep the engine cool during climb.

If you're operating on a normal day with reasonable cylinder head temperatures, you should close the cowl flaps just BEFORE you level the airplane for cruise. Engine overhaul shops suggest that shock cooling or heating of an aircraft engine is anathema to long engine life. If you close the cowl flaps during top of climb when the airplane is operating at Vy or slightly faster, you won't be subjecting the engine to any major shock because of the relatively low climb speed. Conversely, wait until the airplane has accelerated to full cruise, and closing the cowl flaps will cause shock heating. The difference in ram air pressure inside the cowling will be far more dramatic.

6] At what point before your destination should you initiate your descent?
These days, it seems every GPS manufacturer offers a built-in VNAV program that allows a pilot to program his descent with precision. The automatic tendency is to select a vertical speed such as 500-1000 fpm and reduce power to keep airspeed consistent with normal cruise.

Assuming you're flying VFR below 18,000 feet and there are no obstacles in the way, you might be money ahead to settle for a slightly gentler descent at normal cruise power, minding the mixture as you fly into more oxygen rich air. Depending upon your airplane's drag profile, you might be able to save both time and money by dialing in a descent at a minimal 300 fpm. If you're flying with a tailwind, you'll want to maximize benefits from the free push, and a more gradual descent will offer that more favorable wind longer.

If much of your flying is in the Southeast or Southwest as mine is where low level heating can become uncomfortable in summer, you might want to consider a two-step descent, 300 fpm until you reach about 5000 feet AGL, then, increase to 700 fpm or more to minimize time in the hotter, lower altitudes. Most reasonably clean airplanes will accelerate disproportionate to their fuel burn, and you'll wind up arriving at your target altitude and distance having burned less fuel and spent less time in the descent.

A comparatively high drag design such as a Skyhawk or Cherokee may not realize any benefit from such a practice, but a Mooney or Bonanza could actually turn a slight profit in both time and money. (Pretty obviously, you'd need to temper your choices based on low level turbulence.)

7]When should you extend and retract speed brakes?
Speed brakes can be a wonderful aerodynamic benefit for airplanes with low drag profiles, but some pilots misunderstand their limitations, or more accurately, the lack of them. You can deploy them right up to redline with no adverse effects, and they introduce major drag increase. Extend them near yellow line, and the airplane will react as if it just flew into a wall of Jell-O.

What some pilots don't appreciate is that the bottom limit is pretty much unlimited, as well. Speed brakes can also help dissipate speed around the pattern and may be deployed all the way to the ground, if necessary.

Yes, the standard directive is to retract them prior to landing, but that's more a cosmetic than an operational limitation, with little or no adverse effect if you leave them extended.

Years ago, I was being checked out in a new Beech B36TC Bonanza prior to an editorial trip from Orlando to Oshkosh and on to California. We'd done some air work, and I'd extended the speed brakes for descent prior to our first landing. The check pilot was a courteous, enthusiastic CFI who didn't say much but obviously monitored everything I was doing.

I entered the pattern with speed brakes extended, flew base and final, landed and pulled off the runway for a taxi back, and my check pilot commented, "You really should have retracted the speed brakes for landing. It's dangerous to land with them extended." I asked what would happen if we attempted a takeoff with the speed brakes deployed. He simply shook his head and said that wasn't a good idea. Finally, he consented after moving his seat forward and resting one hand on the yoke.

Of course, there was no difference at all in the takeoff or landing. At speeds below 80 knots, speed brakes made no discernible difference in the Bonanza's handling or stall characteristics. I even reduced the approach speed to a short-field number, 75 knots, and the Bonanza responded with its typical gentle manners.

Later, back at the FBO, the instructor said he never would have thought to try that, but he agreed it made sense that the airplane would manifest virtually no reaction to speed brakes at low airspeeds. He was right.